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Outline Chapter 14 — Treatment - Treatment - Both oral and IV treatment can be used for volume replacement - The goal of therapy are to restore normovolemia - And to correct associated acid-base and electrolyte disorders - Oral Therapy - Usually can be accomplished with increased water and dietary sodium - May use salt tablets - Glucose often added to resuscitation fluids - Provides calories - Promotes intestinal Na reabsorption since there is coupled Na and Glucose similar to that seen in the proximal tubule - Rice based solutions provide more calories and amino acids which also promote sodium reabsorption - 80g/L of glucose with rice vs 20 g/L with glucose alone - IV therapy - Dextrose solutions - Physiologically equivalent to water - For correcting hypernatremia - For covering insensible losses - Watch for hyperglycemia - Footnote warns against giving sterile water - Saline solutions - Most hypovolemic patients have a water and a sodium deficit - Isotonic saline has a Na concentration of 154, similar to that of plasma see page 000 - Half-isotonic saline is equivalent to 550 ml of isotonic saline and 500 of free water. Is that a typo? - 3% is a liter of hypertonic saline and 359 extra mEq of Na - Dextrose in saline solutions - Give a small amount of calories, otherwise useless - Alkalinizing solutions - 7.5% NaHCO3 in 50 ml ampules 44 mEq of Na and 44 mEq of HCO3 - Treat metabolic acidosis or hyperkalemia - Why 44 mEq and not 50? - Do not give with calcium will form insoluble CaCO3 - Polyionic solutions - Ringers contains physiologic K and Ca - Lactated Ringers adds 28 mEq of lactate - Spreads myth of LR in lactic acidosis - Potassium chloride - Available as 2 mEq/mL - Do not give as a bolus as it can cause fatal hyperkalemia - Plasma volume expanders - Albumin, polygelastins, hetastarch are restricted to vascular space - 25% albumin can pull fluid into the vascular space - 25% albumin is an albumin concentration of 25 g/dL compare to physiologic 4 g/dL - Says it pulls in several times its own volume - 5% albumin is like giving plasma - Blood - Which fluid? - Look at osmolality, give hypotonic fluids to people with high osmolality - Must include all electrolytes - Example of adding 77 mEw of K to 0.45 NS and making it isotonic - DI can be replaced with dextrose solutions, pure water deficit - Case 14-3 - Diarrhea with metabolic acidosis - He chooses 0.25 NS with 44 mEq of NaCl and 44 NaHCO3 - Talks about blood and trauma - Some studies advocate delaying saline until penetrating trauma is corrected APR about to. Keep BP low to prevent bleeding. Worry about diluting coagulation factors - Only do this if the OR is quickly available - Volume deficit - Provides formula for water deficit and sodium deficit - Do not work for isotonic losses - Provides a table to adjust fluid loss based on changes in Hgb or HCTZ - Says difficult to estimate it from lab findings and calculations - Follow serial exams - Serial urine Na - Rate of replacement - Goal is not to give fluid but to induce a positive balance - Suggests 50-100 ml/hr over what is coming out of the body - Urine - Insensibles 30-50 - Diarrhea - Tubes - Hypovolemic shock - Due to bleeding - Sequesting in third space - Why shock? - Progressive volume depletion leads to - Increased sympathetic NS - Increased Ang 2 - Initially this maintains BP, cerebral and coronary circulation - But this can decrease splanchnic, renal and mucocutaneous perfusion - This leads to lactic acicosis - This can result in intracellular contents moving into circulation or translocation of gut bacteria - Early therapy to prevent irreversible shock - In dogs need to treat with in 2 hours - In humans may need more than 4 hours - Irreversible shock associated with pooling of blood in capillaries - Vasomotor paralysis - Hyperpolarization of vascular smooth muscle as depletion of ATP allows K to flowing out from K channels...

Outline Chapter 14 - Hypovolemic States - Etiology - True volume depletion occurs when fluid is lost from from the extracellular fluid at a rate exceeding intake - Can come the GI tract - Lungs - Urine - Sequestration in the body in a “third space” that is not in equilibrium with the extracellular fluid. - When losses occur two responses ameliorate them - Our intake of Na and fluid is way above basal needs - This is not the case with anorexia or vomiting - The kidney responds by minimizing further urinary losses - This adaptive response is why diuretics do not cause progressive volume depletion - Initial volume loss stimulates RAAS, and possibly other compensatory mechanisms, resulting increased proximal and collecting tubule Na reabsorption. - This balances the diuretic effect resulting in a new steady state in 1-2weeks - New steady state means Na in = Na out - GI Losses - Stomach, pancreas, GB, and intestines secretes 3-6 liters a day. - Almost all is reabsorbed with only loss of 100-200 ml in stool a day - Volume depletion can result from surgical drainage or failure of reabsorption - Acid base disturbances with GI losses - Stomach losses cause metabolic alkalosis - Intestinal, pancreatic and biliary secretions are alkalotic so losing them causes metabolic acidosis - Fistulas, laxative abuse, diarrhea, ostomies, tube drainage - High content of potassium so associated with hypokalemia - [This is a mistake for stomach losses] - Bleeding from the GI tract can also cause volume depletion - No electrolyte disorders from this unless lactic acidosis - Renal losses - 130-180 liters filtered every day - 98-99% reabsorbed - Urine output of 1-2 liters - A small 1-2% decrease in reabsorption can lead to 2-4 liter increase in Na and Water excretion - 4 liters of urine output is the goal of therapeutic diuresis which means a reduction of fluid reabsorption of only 2% - Diuretics - Osmotic diuretics - Severe hyperglycemia can contribute to a fluid deficit of 8-10 Iiters - CKD with GFR < 25 are poor Na conservers - Obligate sodium losses of 10 to 40 mEq/day - Normal people can reduce obligate Na losses down to 5 mEq/day - Usually not a problem because most people eat way more than 10-40 mEq of Na a day. - Salt wasting nephropathies - Water losses of 2 liters a day - 100 mEq of Na a day - Tubular and interstitial diseases - Medullary cystic kidney - Mechanism - Increased urea can be an osmotic diuretic - Damage to tubular epithelium can make it aldo resistant - Inability to shut off natriuretic hormone (ANP?) - The decreased nephro number means they need to be able to decrease sodium reabsorption per nephron. This may not be able to be shut down acutely. - Experiment, salt wasters can stay in balance if sodium intake is slowly decreased. (Think weeks) - Talks about post obstruction diuresis - Says it is usually appropriate rather than inappropriate physiology. - Usually catch up solute and water clearance after releasing obstruction - Recommends 50-75/hr of half normal saline - Talks briefly about DI - Skin and respiratory losses - 700-1000 ml of water lost daily by evaporation, insensible losses (not sweat) - Can rise to 1-2 liters per hour in dry hot climate - 30-50 mEq/L Na - Thirst is primary compensation for this - Sweat sodium losses can result in hypovolemia - Burns and exudative skin losses changes the nature of fluid losses resulting in fluid losses more similar to plasma with a variable amount of protein - Bronchorrhea - Sequestration into a third space - Volume Deficiency produced by the loss of interstitial and intravascular fluid into a third space that is not in equilibrium with the extracellular fluid. - Hip fracture 1500-2000 into tissues adjacent to fxr - Intestinal obstruction, severe pancreatitis, crush injury, bleeding, peritonitis, obstruction of a major venous system - Difference between 3rd space and cirrhosis ascities - Rate of accumulation, if...

References JC mentioned that the diagnostic accuracy of 24 hour urine collection increases with more collections! Metabolic evaluation of patients with recurrent idiopathic calcium nephrolithiasis We didn't refer to a particular study on sodium intake and the 24 hour urine but this meta-analysis Comparison of 24‐hour urine and 24‐hour diet recall for estimating dietary sodium intake in populations: A systematic review and meta‐analysis - PMC 24‐hour diet recall underestimated population mean sodium intake. Anna looking up ace i and urinary sodium Effects of ACE inhibition on proximal tubule sodium transport | American Journal of Physiology-Renal Physiology The original FENa paper by Espinel: The FeNa Test: Use in the Differential Diagnosis of Acute Renal Failure | JAMA | JAMA Network Schreir’s replication and expansion of Espinel’s data: Urinary diagnostic indices in acute renal failure: a prospective study Here’s a report from our own JC on the Diagnostic Utility of Serial Microscopic Examination of the Urinary Sediment in Acute Kidney Injury | American Society of Nephrology JC shared his journey regarding FENa and refers to his recent paper Concomitant Identification of Muddy Brown Granular Casts and Low Fractional Excretion of Urinary Sodium in AKI And Melanie’s accompanying editorial Mind the Cast: FENa versus Microscopy in AKI : Kidney360 (with a great image from Samir Parikh) JC referenced this study from Schrier on FENa with a larger series: Urinary diagnostic indices in acute renal failure: a prospective study ​​Nonoliguric Acute Renal Failure Associated with a Low Fractional Excretion of Sodium | Annals of Internal Medicine Urine sodium concentration to predict fluid responsiveness in oliguric ICU patients: a prospective multicenter observational study | Critical Care | Full Text A classic favorite: Acute renal success. The unexpected logic of oliguria in acute renal failure Marathon runners had granular casts in their urine without renal failure. Kidney Injury and Repair Biomarkers in Marathon Runners Cute piece from Rick Sterns on urine electrolytes! Managing electrolyte disorders: order a basic urine metabolic panel The Urine Anion Gap: Common Misconceptions | American Society of Nephrology The urine anion gap in context CJASN Excellent review from Halperin on urine chemistries (including some consideration of the TTKG): Use of Urine Electrolytes and Urine Osmolality in the Clinical Diagnosis of Fluid, Electrolytes, and Acid-Base Disorders - Kidney International Reports Renal tubular acidosis (RTA): Recognize The Ammonium defect and pHorget the urine pH | SpringerLink Outline Chapter 13 - New part: Part 3, Physiologic approach to acid-base and electrolyte disorders - Do you remember the previous two parts? - Renal physiology - Regulation of water and electrolyte balance - Chapter 13: Meaning and application of urine chemistries - Measurement of urinary electrolyte concentrations, osmolality and pH helps diagnose some conditions - There are no fixed normal values - Kidney varies rate of excretion to match intake and endogenous production - Example: urine Na of 125/day can be normal if patient euvolemic on a normal diet, and wildly inappropriate in a patient who is volume depleted. - Urine chemistries are: - Useful - Simple - Widely available - Usually a random sample is adequate - 24-hour samples give additional context - Gives example of urinary potassium, with extra renal loss of K, urine K should be < 25, but if the patient has concurrent volume deficiency and urine output is only 500 mL, then urine K concentration can appropriately be as high as 40 mEq/L - Table 13-1 - Seems incomplete, see my notes on page 406 - What is Gravity ARF? - Sodium Excretion - Kidney varies Na to maintain effective circulating volume (I’d say volume homeostasis) - Urine Na affected by RAAS and ANP - Na concentration can be used to determine volume status - Urine Na < 20 is hypovolemia -...

References We considered the complexity of the machinery to excrete ammonium in the context of research on dietary protein and how high protein intake may increase glomerular pressure and contribute to progressive renal disease (many refer to this as the “Brenner hypothesis”). Dietary protein intake and the progressive nature of kidney disease: the role of hemodynamically mediated glomerular injury in the pathogenesis of progressive glomerular sclerosis in aging, renal ablation, and intrinsic renal disease A trial that studied low protein and progression of CKD The Effects of Dietary Protein Restriction and Blood-Pressure Control on the Progression of Chronic Renal Disease (and famously provided data for the MDRD eGFR equation A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of Diet in Renal Disease Study Group We wondered about dietary recommendations in CKD. of note, this is best done in the DKD guidelines from KDIGO Executive summary of the 2020 KDIGO Diabetes Management in CKD Guideline: evidence-based advances in monitoring and treatment. Joel mentioned this study on red meat and risk of ESKD. Red Meat Intake and Risk of ESRD We referenced the notion of a plant-based diet. This is an excellent review by Deborah Clegg and Kathleen Hill Gallant. Plant-Based Diets in CKD : Clinical Journal of the American Society of Nephrology Here’s the review that Josh mentioned on how the kidney appears to sense pH Molecular mechanisms of acid-base sensing by the kidney Remarkably, Dr. Dale Dubin put a prize in his ECG book Free Car Prize Hidden in Textbook Read the fine print: Student wins T-bird A review of the role of the kidney in DKA: Diabetic ketoacidosis: Role of the kidney in the acid-base homeostasis re-evaluated Josh mentioned the effects of infusing large amounts of bicarbonate The effect of prolonged administration of large doses of sodium bicarbonate in man and this study on the respiratory response to a bicarbonate infusion: The Acute Effects In Man Of A Rapid Intravenous Infusion Of Hypertonic Sodium Bicarbonate Solution. Ii. Changes In Respiration And Output Of Carbon Dioxide This is the study of acute respiratory alkalosis in dogs: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC293311/?page=1 And this is the study of medical students who went to the High Alpine Research Station on the Jungfraujoch in the Swiss Alps https://www.nejm.org/doi/full/10.1056/nejm199105163242003 Self explanatory! A group favorite! It Is Chloride Depletion Alkalosis, Not Contraction Alkalosis Effects of chloride and extracellular fluid volume on bicarbonate reabsorption along the nephron in metabolic alkalosis in the rat. Reassessment of the classical hypothesis of the pathogenesis of metabolic alkalosis A review of pendrin’s role in volume homeostasis: The role of pendrin in blood pressure regulation | American Journal of Physiology-Renal Physiology Infusion of bicarbonate may lead to a decrease in respiratory stimulation but the shift of bicarbonate to the CSF may lag. Check out this review Neural Control of Breathing and CO2 Homeostasis and this classic paper Spinal-Fluid pH and Neurologic Symptoms in Systemic Acidosis. Outline Outline: Chapter 11 - Regulation of Acid-Base Balance - Introduction - Bicarb plus a proton in equilibrium with CO2 and water - Can be rearranged to HH - Importance of regulating pCO2 and HCO3 outside of this equation - Metabolism of carbs and fats results in the production of 15,000 mmol of CO2 per day - Metabolism of protein and other “substances” generates non-carbonic acids and bases - Mostly from sulfur containing methionine and cysteine - And cationic arginine and lysine - Hydrolysis of dietary phosphate that exists and H2PO4– - Source of base/alkali - Metabolism of an ionic amino acids - Glutamate and asparatate - Organic anions going through gluconeogenesis - Glutamate, Citrate and lactate - Net effect on...

The Channelers went where no nephrology podcasters have gone before, recording in front of a live audience at the National Kidney Foundation Clinical Meeting in Austin. We had all eight Channelers doing a live podcast. We did a Freely Filtered-inspired draft of the best diuretics. The draft order: Leticia Rolon Anna Gaddy Joel Topf Roger Rodby Josh Waitzman Amy Yau JC Velez And Melanie Hoenig References JC Tolvaptan in Later-Stage Autosomal Dominant Polycystic Kidney Disease Intravenous conivaptan for the treatment of hyponatraemia caused by the syndrome of inappropriate secretion of antidiuretic hormone in hospitalized patients: a single-centre experience Rapidity of Correction of Hyponatremia Due to Syndrome of Inappropriate Secretion of Antidiuretic Hormone Following Tolvaptan Tolvaptan, a Selective Oral Vasopressin V2-Receptor Antagonist, for Hyponatremia Josh Review on amiloride development https://pubmed.ncbi.nlm.nih.gov/7039345/ Toad bladder: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1351665/ Amiloride derivatives that inhibit flagella: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8544414/ Amiloride as taste sensor: https://www.science.org/doi/10.1126/science.6691151 Batlle on diabetes Insipidus: https://www.nejm.org/doi/full/10.1056/NEJM198502143120705?query=recirc_curatedRelated_article Amiloride + ddavp for DI https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2518801/ Amy Treatment of refractory congestive heart failure and normokalemic hypochloremic alkalosis with acetazolamide and spironolactone. Acetazolamide reversibly inhibits water conduction by aquaporin-4 Inhibition of Human Aquaporin-1 Water Channel Activity by Carbonic Anhydrase Inhibitors Acetazolamide Attenuates Lithium-Induced Nephrogenic Diabetes Insipidus Acetazolamide in Lithium-Induced Nephrogenic Diabetes Insipidus In Vivo Antibacterial Activity of Acetazolamide Roger 50th anniversary of aldosterone Joel Sotagliflozin in Patients with Diabetes and Recent Worsening Heart Failure The SGLT2 inhibitor empagliflozin in patients hospitalized for acute heart failure: a multinational randomized trial Effects of Early Empagliflozin Initiation on Diuresis and Kidney Function in Patients With Acute Decompensated Heart Failure (EMPAG-HF) Empagliflozin and Heart failure: Diuretic and Cardiorenal Effects Anna Clinical Results of Treatment of Diabetes Insipidus with Drugs of the Chlorothiazide Series Treatment of nephrogenic diabetes insipidus with hydrochlorothiazide and amiloride Influence of renal nerves and sodium balance on the acute antidiuretic effect of bendroflumethiazide in rats with diabetes insipidus Antidiuretic effect of hydrochlorothiazide in lithium-induced nephrogenic diabetes insipidus is associated with upregulation of aquaporin-2, Na-Cl co-transporter, and epithelial sodium channel Major Outcomes in High-Risk Hypertensive Patients Randomized to Angiotensin-Converting Enzyme Inhibitor or Calcium Channel Blocker vs Diuretic Walsh AC, Moyes A. Intractable Congestive Heart Failure Successfully Treated With Southey Tubes. Can Med Assoc J. 1964 Jun 13;90(24):1375-6. Godwin TF, Gunton RW. Clinical trial of a new diuretic, furosemide: comparison with hydrochlorothiazide and mercaptomerin. Can Med Assoc J. 1965 Dec 18;93(25):1296-300. Gerber JG. Role of prostaglandins in the hemodynamic and tubular effects of furosemide. Fed Proc. 1983 Apr;42(6):1707-10. Schlatter E, Salomonsson M, Persson AE, Greger R. Macula densa cells sense luminal NaCl concentration via furosemide sensitive Na+2Cl-K+ cotransport. Pflugers Arch. 1989 Jul;414(3):286-90. doi: 10.1007/BF00584628.

References We considered the effect of a high protein diet and potential metabolic acidosis on kidney function. This review is of interest by Donald Wesson, a champion for addressing this issue and limiting animal protein: Mechanisms of Metabolic Acidosis-Induced Kidney Injury in Chronic Kidney Disease Hostetter explored the effect of a high protein diet in the remnant kidney model with 1 ¾ nephrectomy. Rats with reduced dietary acid load (by bicarbonate supplementation) had less tubular damage. Chronic effects of dietary protein in the rat with intact and reduced renal mass Wesson explored treatment of metabolic acidosis in humans with stage 3 CKD in this study. Treatment of metabolic acidosis in patients with stage 3 chronic kidney disease with fruits and vegetables or oral bicarbonate reduces urine angiotensinogen and preserves glomerular filtration rate In addition to the effect of metabolic acidosis from a diet high in animal protein, this diet also leads to hyperfiltration. This was demonstrated in normal subjects; ingesting a protein diet had a significantly higher creatinine clearance than a comparable group of normal subjects ingesting a vegetarian diet. Renal functional reserve in humans: Effect of protein intake on glomerular filtration rate.This finding has been implicated in Brenner’s theory regarding hyperfiltration: The hyperfiltration theory: a paradigm shift in nephrology One of multiple publications from Dr. Nimrat Goraya whom Joel mentioned in the voice over: Dietary Protein as Kidney Protection: Quality or Quantity? We wondered about the time course in buffering a high protein meal (and its subsequent acid load on ventilation) and Amy found this report:Effect of Protein Intake on Ventilatory Drive | Anesthesiology | American Society of Anesthesiologists Roger mentioned that the need for acetate to balance the acid from amino acids in parenteral nutrition was identified in pediatrics perhaps because infants may have reduced ability to generate acid. Randomised controlled trial of acetate in preterm neonates receiving parenteral nutrition - PMC He also recommended an excellent review on the complications of parenteral nutrition by Knochel https://www.kidney-international.org/action/showPdf?pii=S0085-2538%2815%2933384-6 which explained that when the infused amino acids disproportionately include cationic amino acids, metabolism led to H+ production. This is typically mitigated by preparing a solution that is balanced by acetate. Amy mentioned this study that explored the effect of protein intake on ventilation: Effect of Protein Intake on Ventilatory Drive | Anesthesiology | American Society of Anesthesiologists Anna and Amy reminisced about a Skeleton Key Group Case from the renal fellow network Skeleton Key Group: Electrolyte Case #7 JC wondered about isolated defects in the proximal tubule and an example is found here: Mutations in SLC4A4 cause permanent isolated proximal renal tubular acidosis with ocular abnormalities Anna’s Voiceover re: Gastric neobladder → metabolic alkalosis and yes, dysuria. The physiology of gastrocystoplasty: once a stomach, always a stomach but not as common as you might think Gastrocystoplasty: long-term complications in 22 patients Sjögren’s syndrome has been associated with acquired distal RTA and in some cases, an absence of the H+ ATPase, presumably from autoantibodies to this transporter. Here’s a case report: Absence of H(+)-ATPase in cortical collecting tubules of a patient with Sjogren's syndrome and distal renal tubular acidosis Can't get enough disequilibrium pH? Check this out- Spontaneous luminal disequilibrium pH in S3 proximal tubules. Role in ammonia and bicarbonate transport. Acetazolamide secretion was studied in this report Concentration-dependent tubular secretion of acetazolamide and its inhibition by salicylic acid in the isolated perfused rat kidney. | Drug Metabolism & Disposition In this excellent review, David Goldfarb tackles the...

References for Chapter 10 We did not mention many references in our discussion today but our listeners may enjoy some of the references below. Effects of pH on Potassium: New Explanations for Old Observations - PMC although the focus of this article is on potassium, this elegant review by Aronson and Giebisch reviews intracellular shifts as it relates to pH and K+. Josh swooned for Figure 10-1 is this right? Which figure was it? which shows the relationship between [H+] and pH. You can find this figure in the original reference from Halperin ML and others, Figure 1 here. Factors That Control the Effect of pH on Glycolysis in Leukocytes Here’s Leticia Rolon’s favorite Henderson-Hasselbalch calculator website: ​​Henderson-Hasselbalch Calculator | Buffer Solutions [hint! for this site, use the bicarbonate (or “total CO2”) for A- and PCO2 for the HA] There’s also a cooking tab for converting units! Fundamentals of Arterial Blood Gas Interpretation - PMC this review published posthumously from the late but beloved Jerry Yee and his group at Henry Ford Hospital, explores the details and underpinnings of our understandings of arterial blood gas interpretation (and this also addresses how our colleagues in clinical chemistry measure total CO2 - which JC referenced- but JC said “machine” and our colleagues prefer the word “instrument.”) Amy went deep on bicarbonate in respiratory acidosis. Here are her refs: Sodium bicarbonate therapy for acute respiratory acidosis Sodium Bicarbonate in Respiratory Acidosis Bicarbonate therapy in severe metabolic acidosis Effect of Intravenous Sodium Bicarbonate on Ventilation, Gas Exchange, and Acid-Base Balance in Patients with Chronic Pulmonary Insufficiency Bicarbonate Therapy in Severe Metabolic Acidosis | American Society of Nephrology this review article from Sabatini and Kurtzman addresses the issues regarding bicarbonate therapy including theoretical intracellular acidosis. Bicarbonate in DKA? Don’t do it: Bicarbonate in diabetic ketoacidosis - a systematic review Here’s a review from Bushinsky and Krieger on the effect acidosis on bone https://www.sciencedirect.com/science/article/abs/pii/S0085253822002174 Here is the primary resource that Anna used in here investigation of meat replacements Nutritional Composition of Novel Plant-Based Meat Alternatives and Traditional Animal-Based Meats We enjoyed this paper that Dr. Rose references from the Journal of Clinical Investigation 1955 in which investigators infused HCl into nephrectomized dogs and observed changes in extracellular ions. https://www.jci.org/articles/view/103073/pd We wondered about the amino acids/protein in some available meat alternatives they are explored in this article in the journal Amino Acids: Protein content and amino acid composition of commercially available plant-based protein isolates - PMC and you may enjoy this exploration of the nutritional value of these foods: Full article: Examination of the nutritional composition of alternative beef burgers available in the United States Outline Chapter 10: Acid-Base Physiology - H concentration regulated tightly - Normal H+ is 40 nm/L - This one millionth the concentration of Na and K - It needs to be this dilute because H+ fucks shit up - Especially proteins - Cool foot note H+ actually exists as H3O+ - Under normal conditions the H+ concentration varies little from normal due to three steps - Chemical buffering by extracellular and intracellular bufffers - Control of partial pressure of CO2 by alterations of alveolar ventilation - Control of plasma bicarbonate by changes in renal H+ excretion - Acid and bases - Use definition by Bronsted - Acid can donate protons - Base can accept protons - There are two classes of acids** - Carbonic acid H2CO3 - Each day 15000 mmol of CO2 are generated - CO2 not acid but combines with water to form carbonic acid H2CO3 - CO2 cleared by the lungs - Noncarbonic acid - Formed from metabolism of protein....

References for Chapter 9 One of the few papers that Rose wrote as a single author explores electrolyte free water clearance. This seminal paper explores the issue in greater detail than the book. A New approach to disturbances in the plasma sodium concentration Wondering about the volume of sweat? Josh taught us that the volume of “transepidermal volume loss” is not affected by humidity https://www.jidonline.org/article/S0022-202X(15)48145-X/pdf but is greatly affected by temperature: Skin temperature and transepidermal water loss Regarding normal sweat physiology, there is a nice review (with figures!) titled Physiological mechanisms determining sweat composition which describes all the important cells and channels which make up sweat glands. And an important follow on paper titled Higher Bioelectric Potentials due to Decreased Chloride Absorption in the Sweat Glands of Patients with Cystic Fibrosis describing specifically the sweat characteristics of patients with cystic fibrosis. Melanie was enchanted by work from RA McCance who did early experiments to induce sodium deficiency using very low sodium diets and a homemade sauna-like tent. His musings are fascinating. Lancet 1936 Experimental human salt deficiency MEDICAL PROBLEMS IN MINERAL METABOLISM Age-related decline in urine concentration may not be universal: Comparative study from the US and two small-scale societies from Jeff Sands (of urea transport fame!) In this initial report, after continually water loading 21 volunteers, the younger group (mean age 31) had a urine osmolality of 52 mOsm/kg compared to in the older group (mean age 84). Influence of age, renal disease, hypertension, diuretics, and calcium on the antidiuretic responses to suboptimal infusions of vasopressin. In a later report older subjects (mean age 72) vs younger controls (mean age 26) drank 20 ml/kg over 40 minutes. The younger group excreted more of the water in the first 2 hours and had a lower mean urine osmolality 86 vs 112 mOsm/kg compared to the older participants. Age-associated Alterations in Thirst and Arginine Vasopressin in Response to a Water or Sodium Load Howard Furst suggests the urine to plasma electrolyte ratio as a simpler strategy to consider the free water clearance: https://nephrology.edublogs.org/files/2014/03/Water-Restriction-in-Hyponatremia1-1eb8n40.pdf or via pubmed: The urine/plasma electrolyte ratio: a predictive guide to water restriction Rapidity of Correction of Hyponatremia Due to Syndrome of Inappropriate Secretion of Antidiuretic Hormone Following Tolvaptan InfoSnack picture of pre and post tolvaptan

References for chapter 8 Robert Schrier proposed a unifying hypothesis to explain the sodium retention seen in edematous states like cirrhosis and heart failure, coining the term effective arterial blood volume (EABV). An open access review in JASN 2007 can be found here: https://jasn.asnjournals.org/content/18/7/2028#ref-3 John P Peters ASN Annual Award: https://www.asn-online.org/about/awards/award.aspx?awh_key=0ea83199-f86d-4506-9507-d7e4ce688cb4 Short article discussing contributions of Dr. Peters by mentees Dr. Franklin Epstein and Dr. Donald Seldin: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2588700/ and https://pubmed.ncbi.nlm.nih.gov/12097739/ Epstein FH et al. Studies of the antidiuresis of quiet standing: the importance of changes in plasma volume and glomerular filtration. JCI 1950. In this classic report, investigators studied their own sodium excretion supine, standing and with a variety of maneuvers (saline or albumin infusion) and showed that urinary sodium excretion is limited in the upright position compared to supine position. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC436228/pdf/jcinvest00414-0077.pdf An interesting review of early concepts on hypertension feature notes on John J Hay and Paul Dudley White. The former was known to say, “The greatest danger to a man with high blood pressure lies in its discovery because then some fool is certain to try and reduce it!” and the latter has been quoted as saying that hypertension might be compensatory but apparently, these quotes are out of context. To find out what they really said, check out: Elias MF and Goodell AL. Setting the record straight for two heroes in hypertension John J Hay and Paul Dudley White. J Clin Hypertens 2019 https://onlinelibrary.wiley.com/doi/epdf/10.1111/jch.13650 VA Cooperative Trial was an important study to establish the hypertension should, in fact, be treated The VA Cooperative Study and the Beginning of Routine Hypertension Screening, 1964-1980 This study was stopped after only 18 months because of an excess of deaths in the untreated group who had a mean diastolic BP of 115 mmHg. For a long time, only the diastolic BP was felt to be important until the Systolic Hypertension in Elderly Patients (“SHEP study”) clarified that treatment of isolated systolic hypertension is also important Prevention of Stroke by Antihypertensive Drug Treatment in Older Persons With Isolated Systolic Hypertension We continued to try to grapple with the work of Jens Titze on sodium which turns many of our assumptions about sodium upside down. His team studied astronauts on a long term high sodium diet and found an unexpected weekly (circaseptan) rhythm seemingly related inversely to aldosterone and directly with cortisol. His work also probes our notion of body sodium content. For a great first hand read, check out Dr TItze’s review in Kidney International 2014 which he aptly dubs, “Spooky Sodium Balence.” https://www.sciencedirect.com/science/article/pii/S0085253815562807 Epstein M. The cardiovascular and renal effects of head-out of water Immersion in Man. Circulation Research 1976 Cardiovascular and renal effects of head-out water immersion in man: application of the model in the assessment of volume homeos Space flight is an exaggeration of the water immersion experiments. Astronauts on either a low or normal sodium diet had a reset of natriuetic peptides. A Salty Tale: Study Examines Sodium Regulation in Space and Natriuretic Peptide Resetting in Astronauts | Circulation Baroreceptors feature mechanically activated ion channels called PIEZO1 and PIEZO2. Zeng W, Marshall KL, Min S, Daou I, Chapleau MW, Abboud FM. PIEZOs mediate neuronal sensing of blood pressure and the baroreceptor reflex. Science 2018 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102061/ We also relearned an unfortunate truth: lots of folks pee in pools. De Laat et al. Water Res. 2011. Concentration levels of urea in swimming pool water and reactivity of chlorine...

Chapter 7 References Sands JM, Blount MA and Klein JD. Regulation of Renal Urea Transport by Vasopressin. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3116377/ In this invited piece, Sands and colleagues explain that although urea is permeable across membranes, this is slow, thus urea transporters in the kidney, under control of vasopressin, are needed to facilitate transport and create the medullary gradient. Text book using 20% of extracellular compartment being in the intravascular compartment. https://courses.lumenlearning.com/ap2/chapter/body-fluids-and-fluid-compartments-no-content/ another one: https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Book%3A_Anatomy_and_Physiology_(Boundless)/25%3A_Body_Fluids_and_Acid-Base_Balance/25.2%3A_Body_Fluids/25.2B%3A_Fluid_Compartments The chapter I wrote where I went through the math in figure 7-3. It was a major revelation to me: https://docs.google.com/document/d/17BM1xihvlztuQlU8GVNhEDoPLzr6GounHYZAtVUkLvw/edit?usp=sharing Association Between ICU-Acquired Hypernatremia and In-Hospital Mortality https://journals.lww.com/ccejournal/fulltext/2020/12000/association_between_icu_acquired_hypernatremia_and.26.aspx Rate of Correction of Hypernatremia and Health Outcomes in Critically Ill Patients https://pubmed.ncbi.nlm.nih.gov/30948456/ Edelman IS, Leibman J, O’Meara MP and Birkenfeld LW. Interrelations between serum sodium concentration, serum osmolarity and total exchangeable sodium, total exchangeable potassium and total body water. JCI 1958. This classic paper calculates the total body exchangeable sodium and potassium and establishes the relationship between these. Understanding this painstacking work helps understand the effect of supplementing potassium in the setting of hyponatremia. https://dm5migu4zj3pb.cloudfront.net/manuscripts/103000/103712/cache/103712.1-20201218131357-covered-e0fd13ba177f913fd3156f593ead4cfd.pdf Edelman is the Root of Almost All Good in Nephrology https://www.renalfellow.org/2014/11/20/edelman-is-root-of-almost-all-good-in/ Jens Titze and his team published a pair of articles that shocked those interested in salt and water in JCI in 2017. High Salt intake reprioritizes osmolyte and energy metabolism for body fluid conservation https://www.jci.org/articles/view/88532 Increased salt consumption induces body water conservation and decreases fluid intake https://www.jci.org/articles/view/88530 in this exciting exploration of the basic assumptions that we hold true regarding salt and water (and staring Russian cosmonauts and an incredible controlled simulation of salt and water intake), Titze shows that high sodium intake does not simply drive water consumption (as we usually teach) but instead leads to a complex hormonal and metabolic response (even with diurnal variation!) and results in body water conservation and decreased water consumption. And accompanying editorial from Mark Zeidel: salt and water, not so simple. https://www.jci.org/articles/view/94004 In addition, Titze and others have done interesting work on sodium deposition in tissues where it may also be a source for systemic inflammation.https://pubmed.ncbi.nlm.nih.gov/28154199/ Jens Titze talking about salt, water, thirsting a TEDx talk. https://www.youtube.com/watch?v=jQQPBmnIuCY A discussion/debate of the overfill vs. underfill theory of edema in the nephrotic syndrome (hint- overfill theory triumphs) would be incomplete without a reference to congenital analbuminemia. This reference from Frontiers in Genetics explores the diagnosis, phenotype and molecular genetics and reveal that patients tend to have only mild edema but severe hyperlipidemia. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6478806/ The finding that proteinuria can directly lead to sodium retention based on a study when puromycin aminoglycoside induced proteinuria of one kidney lead to sodium retention by that kidney which was localized to the distal nephron....

Chapter 6 part 2. References Josh touts the PARADIGM-HF Trial Angiotensin–Neprilysin Inhibition versus Enalapril in Heart Failure | NEJM which found this combination was superior to an ARB alone Joel mentions an early atrial natriuretic peptide trial by Julie Lewis et al. Atrial natriuretic factor in oliguric acute renal failure - American Journal of Kidney Diseases and here’s a metanalysis that put this option to bed: Atrial Natriuretic Peptide for Management of Acute Kidney Injury: A Systematic Review and Meta-analysis Snack attack? Check out “Snack induced ANP” Snack-Induced Release of Atrial Natriuretic Factor | NEJM Want more natriuretic peptides than we discussed? Check out this review! Cardiac natriuretic peptides | Nature Reviews Cardiology or this fantastic review: Here’s an excellent review of ANP effect on the kidney: ANP-induced signaling cascade and its implications in renal pathophysiology Cerebral salt wasting and elevated brain natriuretic peptide levels after traumatic brain injury: 2 case reports Joel mentions the study which probed CRIC cohort regarding NSAIDs. Association of Opioids and Nonsteroidal Anti-inflammatory Drugs With Outcomes in CKD: Findings From the CRIC (Chronic Renal Insufficiency Cohort) Study - American Journal of Kidney Diseases and you may like the discussion on NephJC: ​​No Pain for the Kidneys from NSAIDs — NephJC The KDIGO guidelines can be found here CKD-Mineral and Bone Disorder (CKD-MBD) – KDIGO Regulation and Effects of FGF23 in Chronic Kidney Disease Elegant work on the calcium sensing receptor by Martin Pollak https://doi.org/10.1016/0092-8674(93)90617-Ye Claudin 14, PTH, and calcium absorption in the loop of Henle: Parathyroid hormone controls paracellular Ca 2+transport in the thick ascending limb by regulating the tight-junction protein Claudin14 Carboxymaltose induced hypophosphatemia by increasing FGF-23. Randomized trial of intravenous iron-induced hypophosphatemia Current "corrected" calcium concept challenged. | The BMJ The Dialysis Encephalopathy Syndrome — Possible Aluminum Intoxication | NEJM NephMadness covered Aluminum binders in 2016. Roger mentioned the use of ferric citrate as a phosphate binder Ferric Citrate Controls Phosphorus and Delivers Iron in Patients on Dialysis | American Society of Nephrology Joel reminded us of the misadventures in efforts to normalize hemoglobin, first in hemodialysis patients The Effects of Normal as Compared with Low Hematocrit Values in Patients with Cardiac Disease Who Are Receiving Hemodialysis and Epoetin | NEJM Later, in patients with CKD, normalization was also not shown to be better: Correction of Anemia with Epoetin Alfa in Chronic Kidney Disease | NEJM , Normalization of Hemoglobin Level in Patients with Chronic Kidney Disease and Anemia | NEJM A quick shout out for roxadustat and the Nephmadness Anemia region! Roxadustat Treatment for Anemia in Patients Undergoing Long-Term Dialysis | NEJM, #NephMadness 2021: Anemia Region – AJKD Blog In this review of vasopressin, you can find an excellent discussion of basic stimuli and vasopressin receptors: Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems | Physiological Reviews X-Linked Nephrogenic diabetes insipidus is very rare and there was theory that all patients originated from the same family and traveled to the US on the Hopewell ship JCI - X-linked nephrogenic diabetes insipidus mutations in North America and the Hopewell hypothesis. This report describes another family from the Netherlands with nephrogenic DI including the finding that the urine osmolarity never exceeds 200 mOsm/kg. Hereditary Nephrogenic Diabetes Insipidus - GeneReviews® (and here’s a family with central diabetes insipidus https://academic.oup.com/jcem/article/81/1/192/2649423?login=true ) Although we have all learned that thiazides should be used with diabetes insipidus, to induce mild volume depletion, several case reports and animal data have found that...

Chapter 6 part 1 In this review of vasopressin, you can find an excellent discussion of basic stimuli and vasopressin receptors: Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems | Physiological Reviews X-Linked Nephrogenic diabetes insipidus is very rare and there was theory that all patients originated from the same family and traveled to the US on the Hopewell ship JCI - X-linked nephrogenic diabetes insipidus mutations in North America and the Hopewell hypothesis. This report describes another family from the Netherlands with nephrogenic DI including the finding that the urine osmolarity never exceeds 200 mOsm/kg. Hereditary Nephrogenic Diabetes Insipidus - GeneReviews® (and here’s a family with central diabetes insipidus https://academic.oup.com/jcem/article/81/1/192/2649423?login=true ) Although we have all learned that thiazides should be used with diabetes insipidus, to induce mild volume depletion, several case reports and animal data have found that acetazolamide might be the best diuretic for the job. Clinicians from Boston Medical Center tried it out in this report: ​​Acetazolamide in Lithium-Induced Nephrogenic Diabetes Insipidus | NEJM based on exciting data in mice! https://jasn.asnjournals.org/content/27/7/2082.short ADH appears to have an effect on potassium excretion. This was investigated by Giebesch who found, with clearance and micropuncture studies in rats plus isolated perfused tubules, ADH increased potassium secretion Influence of ADH on renal potassium handling: A micropuncture and microperfusion study A corollary should be that inhibition of ADH would increase the risk of hyperkalemia but this was not observed in the SALT-1 and SALT-2 trials. 5% of patients developed hyperkalemia in both the tolvaptan group and the placebo group Tolvaptan, a Selective Oral Vasopressin V2-Receptor Antagonist, for Hyponatremia | NEJM V1 vasopressin as a pressor Exogenous Vasopressin-Induced Hyponatremia in Patients With Vasodilatory Shock: Two Case Reports and Literature Review We wondered/debated on our observation that hyponatremia is not reliably seen in patients receiving vasopressin in the ICU. In the VASST trial, Vasopressin versus Norepinephrine Infusion in Patients with Septic Shock, 1 patient in each study arm of nearly 400 patients developed hyponatremia. Note that patients with hyponatremia (<130 mEq/L) were excluded from the study. Excellent review! Vasopressin and the Regulation of Aquaporin-2 This report looks at the PET scan in individuals who are thirsty. Neuroimaging of genesis and satiation of thirst and an interoceptor-driven theory of origins of primary consciousness Here’s a little discussion of Dr. Grant Liddle. In addition to his eponymous syndrome, he coined the term “ectopic” and developed the dexamethasone suppression test. Grant Liddle (1921–1989) : The Endocrinologist This is the sad case of licorice gluttony in NEJM which led to hypokalemia and a cardiac arrest. Case 30-2020: A 54-Year-Old Man with Sudden Cardiac Arrest In this review of the principal and intercalated cells, check out Figure 8 which has an excellent figure of the aldosterone paradox. https://cjasn.asnjournals.org/content/clinjasn/early/2015/01/30/CJN.08880914.full.pdf?with-ds=yes%3Fversioned%3Dtrue Remarkably, licorice has been used in dialysis patients to lower potassium in patients in this short term trial. Glycyr-rhetinic acid food supplementation lowers serum potassium concentration in chronic hemodialysis patients Animal studies on pregnant rats demonstrating the reset osmostat as predicted by Roger. Osmoregulation during Pregnancy in the Rat: EVIDENCE FOR RESETTING OF THE THRESHOLD FOR VASOPRESSIN SECRETION DURING GESTATION

References for Chapter 5--the Distal Nephron Roger pointed out the fact that the distal nephron can achieve very low urinary sodium as evidenced by observations in people from the Yanomamo tribe Blood pressure and electrolyte excretion in the Yanomamo Indians, an isolated population in this report, 84% of the participants had urinary sodium < 1mmol/24 hours. Information about the Yanomamo Tribe. It looks like they’re starting to make chocolate, now! Yanomami The Yanomami are great observers of nature The Amazon's Yanomami utterly abandoned by Brazilian authorities: Report Yanomami Amazon reserve invaded by 20,000 miners; Bolsonaro fails to act I believe this is the original study looking at urine sodium and blood pressure in the Yanomamo Indians, but the INTERSALT trial linked above I believe had more robust urine data This study mentions the average lipid profile for men and women along with BMI. I didn’t mention in the “Voice of God” overview, but there is some interest looking at the Yanomamo and rate of cancer as it relates to the correlation with intracellular potassium to sodium ratios Josh referred back to his notes and realized that the tightest junctions are in the TOAD not FROG bladders Physiology and Function of the Tight Junction An excellent review from McCormick and Ellison on the Distal convoluted tubule in Comprehensive Physiology. We flirt with the disorder of Gordon’s syndrome: Familial Hyperkalemic Hypertension | American Society of Nephrology and its alter ego, Gitelman syndrome: Gitelman Syndrome | Hypertension JC spoke about this beautiful report on how calcineurin inhibitors lead to hyperkalemia (and mimic Gordon’s syndrome). The calcineurin inhibitor tacrolimus activates the renal sodium chloride cotransporter to cause hypertension This superb review of the DCT includes all the highlights of Rose’s chapter 5 with a modern lens including “braking” from DCT hypertrophy Distal Convoluted Tubule | American Society of Nephrology Echos of the lessons learned in the DCT can be seen in this review: Diuretic Treatment in Heart Failure | NEJM Anna reminds us of the ALL HAT trial which showed that chlorthalidone was superior to the lisinopril and amlodipine groups (and the alpha blocker dropped out earlier) ​​Major Outcomes in High-Risk Hypertensive Patients Randomized to Angiotensin-Converting Enzyme Inhibitor or Calcium Channel Blocker vs Diuretic Nice review of drug induced Hyperuricemia with a deep dive into the mechanisms of diuretic induced Hyperuricemia. Drug-induced hyperuricaemia and gout Plus, despite the concerns that thiazides are weaker than loop diuretics and may not work in CKD, this report suggests that it can still be of use. Chlorthalidone for poorly controlled hypertension in chronic kidney disease: an interventional pilot study If you love diuretics, you will love this classic paper from Craig Brater on diuretics Diuretic Therapy | NEJM which also includes the t1/2 of various diuretics and points out that chlorthalidone’s half life is 24-55 hours so eliminated after 4-10 days. The hypercalcemia seen in some patients who take thiazides may be the unmasking of primary hyperparathyroidism Thiazide-Associated Hypercalcemia: Incidence and Association With Primary Hyperparathyroidism Over Two Decades As we discussed the relative importance of DCT vs Proximal tubule for the hypercalcemia seen with thiazides, Amy reminded us of about the TRPV5 knockout mice: JCI - Renal Ca2+ wasting, hyperabsorption, and reduced bone thickness in mice lacking TRPV5 JC mentioned the defect in TRPM6 that can cause severe hypomagnesemia: Novel TRPM6 Mutations in 21 Families with Primary Hypomagnesemia and Secondary Hypocalcemia We enjoyed talking about Liddle syndrome Hypertension caused by a truncated epithelial sodium channel γ subunit: genetic heterogeneity of Liddle syndrome We wondered about the role of pendrin which was discovered after this book was published. Here’s a nice review: The role...

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Chapter Three: How the proximal tubule is like Elizabeth Warren and other truths my friends from Boston taught me

The exciting conclusion to Chapter Two: Renal Circulation and Glomerular Filtration Rate

Back by popular demand…all two of you…the second chapter of The Clinical Physiology of Acid Base and Electrolyte Disorders.

The Channel Gang discusses the name of their new podcast and then discuss chapter one of The Book.