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Oliveira J, Freitas J, Sala I, Tavares J, Santos S, Cabrita A. Diet and exercise induced hypokalemia. Nefrologia 2023; 43 Suppl 2:96-98. [PMID: 36517363 DOI: 10.1016/j.nefroe.2021.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 12/27/2021] [Indexed: 06/17/2023] Open
Affiliation(s)
- João Oliveira
- Centro Hospitalar e Universitário do Porto, Porto, Portugal.
| | - Joana Freitas
- Centro Hospitalar e Universitário do Porto, Porto, Portugal
| | - Inês Sala
- Centro Hospitalar e Universitário do Porto, Porto, Portugal
| | - Joana Tavares
- Centro Hospitalar e Universitário do Porto, Porto, Portugal
| | - Sofia Santos
- Centro Hospitalar e Universitário do Porto, Porto, Portugal
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Diet and exercise induced hypokalemia. Nefrologia 2022. [DOI: 10.1016/j.nefro.2021.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Kamel KS, Halperin ML. Use of Urine Electrolytes and Urine Osmolality in the Clinical Diagnosis of Fluid, Electrolytes, and Acid-Base Disorders. Kidney Int Rep 2021; 6:1211-1224. [PMID: 34013099 PMCID: PMC8116912 DOI: 10.1016/j.ekir.2021.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 02/01/2021] [Indexed: 01/16/2023] Open
Abstract
We discuss the use of urine electrolytes and urine osmolality in the clinical diagnosis of patients with fluid, electrolytes, and acid-base disorders, emphasizing their physiological basis, their utility, and the caveats and limitations in their use. While our focus is on information obtained from measurements in the urine, clinical diagnosis in these patients must integrate information obtained from the history, the physical examination, and other laboratory data.
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Affiliation(s)
- Kamel S. Kamel
- Renal Division, St. Michael’s Hospital and The University of Toronto, Toronto, Ontario, Canada
- Keenan Research Center in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Correspondence: Kamel S. Kamel, University of Toronto, Division of Nephrology, St. Michael’s Hospital, Toronto, Ontario, M5B 1W8, Canada.
| | - Mitchell L. Halperin
- Renal Division, St. Michael’s Hospital and The University of Toronto, Toronto, Ontario, Canada
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Dietary Chloride Deficiency Syndrome: Pathophysiology, History, and Systematic Literature Review. Nutrients 2020; 12:nu12113436. [PMID: 33182508 PMCID: PMC7696598 DOI: 10.3390/nu12113436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/01/2020] [Accepted: 11/02/2020] [Indexed: 11/16/2022] Open
Abstract
Metabolic alkalosis may develop as a consequence of urinary chloride (and sodium) wasting, excessive loss of salt in the sweat, or intestinal chloride wasting, among other causes. There is also a likely underrecognized association between poor salt intake and the mentioned electrolyte and acid-base abnormality. In patients with excessive loss of salt in the sweat or poor salt intake, the maintenance of metabolic alkalosis is crucially modulated by the chloride-bicarbonate exchanger pendrin located on the renal tubular membrane of type B intercalated cells. In the late 1970s, recommendations were made to decrease the salt content of foods as part of an effort to minimize the tendency towards systemic hypertension. Hence, the baby food industry decided to remove added salt from formula milk. Some weeks later, approximately 200 infants (fed exclusively with formula milks with a chloride content of only 2-4 mmol/L), were admitted with failure to thrive, constipation, food refusal, muscular weakness, and delayed psychomotor development. The laboratory work-up disclosed metabolic alkalosis, hypokalemia, hypochloremia, and a reduced urinary chloride excretion. In all cases, both the clinical and the laboratory features remitted in ≤7 days when the infants were fed on formula milk with a normal chloride content. Since 1982, 13 further publications reported additional cases of dietary chloride depletion. It is therefore concluded that the dietary intake of chloride, which was previously considered a "mendicant" ion, plays a crucial role in acid-base and salt balance.
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Hoorn EJ, Bovée DM, Geerse DA, Visser WJ. Diet-Exercise-Induced Hypokalemic Metabolic Alkalosis. Am J Med 2020; 133:e667-e669. [PMID: 32442511 DOI: 10.1016/j.amjmed.2020.04.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 11/27/2022]
Affiliation(s)
- Ewout J Hoorn
- Divisions of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands.
| | - Dominique M Bovée
- Divisions of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Daniël A Geerse
- Department of Internal Medicine, Bravis Hospital, Roosendaal, The Netherlands
| | - Wesley J Visser
- Divisions of Dietetics, Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Wu KL, Cheng CJ, Sung CC, Tseng MH, Hsu YJ, Yang SS, Chau T, Lin SH. Identification of the Causes for Chronic Hypokalemia: Importance of Urinary Sodium and Chloride Excretion. Am J Med 2017; 130:846-855. [PMID: 28213045 DOI: 10.1016/j.amjmed.2017.01.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 01/13/2017] [Accepted: 01/14/2017] [Indexed: 12/27/2022]
Abstract
BACKGROUND Uncovering the correct diagnosis of chronic hypokalemia with potassium (K+) wasting from the kidneys or gut can be fraught with challenges. We identified clinical and laboratory parameters helpful for differentiating the causes of chronic hypokalemia. METHODS Normotensive patients referred to our tertiary academic medical center for the evaluation of chronic hypokalemia were prospectively enrolled over 5 years. Clinical features, laboratory examinations-including blood and spot urine electrolytes, acid-base status, biochemistries, and hormones-as well as genetic analysis, were determined. RESULTS Ninety-nine patients with chronic normotensive hypokalemia (serum K+ 2.8 ± 0.4 mmol/L, duration 4.1 ± 0.9 years) were enrolled. Neuromuscular symptoms were the most common complaints. Although Gitelman syndrome (n = 33), Bartter syndrome (n = 10), and distal renal tubular acidosis (n = 12) were the predominant renal tubular disorders, 44 patients (44%) were diagnosed with anorexia/bulimia nervosa (n = 21), surreptitious use of laxatives (n = 11), or diuretics (n = 12). Patients with gastrointestinal causes and surreptitious diuretics use exhibited a female predominance, lower body mass index, and less K+ supplementation. High urine K+ excretion (transtubular potassium gradient >3, urine K+/Cr >2 mmol/mmol) was universally present in patients with renal tubular disorders, but also found in >50% patients with gastrointestinal causes. Of interest, while urine sodium (Na+) and chloride (Cl-) excretions were high and coupled (urine Na+/Cl- ratio ∼1) in renal tubular disorders and "on" diuretics use, skewed or uncoupled urine Na+ and Cl- excretions were found in anorexia/bulimia nervosa and laxatives abuse (urine Na+/Cl- ratio: 5.0 ± 2.2, 0.4 ± 0.2, respectively) and low urine Na+ and Cl- excretions with fixed Na+/Cl- ratios (0.9 ± 0.2) when "off" diuretics. CONCLUSION Besides body mass index, sex, and blood acid-base status, integrated interpretation of the urine Na+:Cl- excretion and their ratio is important to make an accurate diagnosis and treatment plan for patients with chronic normotensive hypokalemia.
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Affiliation(s)
- Kun-Lin Wu
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Department of Medicine, Armed Forces Taoyuan General Hospital, Taoyuan, Taiwan
| | - Chih-Jen Cheng
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Chih-Chen Sung
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Ming-Hua Tseng
- Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan; Division of Pediatric Nephrology, Department of Pediatrics, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Yu-Juei Hsu
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Sung-Sen Yang
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Tom Chau
- Department of Medicine, Providence St. Vincent Medical Center, Portland, Ore
| | - Shih-Hua Lin
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.
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Delhey PR, Holzapfel BM, Kanz KG, Mayer-Wagner S. Hypokalemia mimicking a herniated vertebral disc. Spine J 2015; 15:e53-6. [PMID: 24215900 DOI: 10.1016/j.spinee.2013.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 07/26/2013] [Accepted: 08/22/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT A herniated vertebral disc is a common cause of paralysis. Other causes include infections, tumors, and neurologic diseases. A rare and dangerous but in most cases easily treatable cause is hypokalemia. Clinically, the acute symptoms may resemble a herniated vertebral disc, but hypokalemia per se is life-threatening by causing heart arrest through ventricular tachycardia or fibrillation. PURPOSE A patient with back pain and neurologic deficit in the lower extremities after a history of a herniated vertebral disc presented, who finally receives the diagnosis of hypokalemia. STUDY DESIGN Case report. METHODS A 25-year-old female patient presenting after a fall with muscle weakness in both legs was followed clinically and radiographically. RESULTS Neurological examination showed a lower extremity muscle weakness with three-fifths muscular strength of the quadriceps and tibialis anterior muscle on both sides. Reflexes were diminished bilaterally, anal sphincter tone was normal. Plain radiography suggested a posterior rim fracture of L5, but computed tomography did not confirm this diagnosis. The laboratory investigation revealed a hypokalemia of 1.7 mEq/L. On electrolyte replacement, the patient recovered immediately. CONCLUSION This report describes a misleading diagnostic case of back pain and neurologic deficit after a trauma and sensitizes for the possible life-threatening diagnosis hypokalemia, which is rare but easily treatable.
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Affiliation(s)
- Patrick Roman Delhey
- Klinikum rechts der Isar, Technical University Munich, Department of Trauma Surgery, Ismaningerstrasse 22, D-81675 Munich, Germany.
| | - Boris Michael Holzapfel
- Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Ave., Kelvin Grove, QLD 4059, Australia
| | - Karl-Georg Kanz
- Klinikum rechts der Isar, Technical University Munich, Department of Trauma Surgery, Ismaningerstrasse 22, D-81675 Munich, Germany; Department of Surgery, Campus Innenstadt, Ludwig-Maximilians-University, Nussbaumstr. 20, D-80336 Munich, Germany
| | - Susanne Mayer-Wagner
- Department of Orthopaedic Surgery, Campus Großhadern, Ludwig-Maximilians-University, Marchioninistr. 15, D-81377 Munich, Germany
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Sung CC, Cheng CJ, Chiang WF, Chau T, Hsu YJ, Yang SS, Lin SH. Etiologic and therapeutic analysis in patients with hypokalemic nonperiodic paralysis. Am J Med 2015; 128:289-96.e1. [PMID: 25447623 DOI: 10.1016/j.amjmed.2014.09.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 09/23/2014] [Accepted: 09/24/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND Hypokalemic nonperiodic paralysis represents a group of heterogeneous disorders with a large potassium (K(+)) deficit. Rapid diagnosis of curable causes with appropriate treatment is challenging to avoid the sequelae of hypokalemia. We prospectively analyzed the etiologies and therapeutic characteristics of hypokalemic nonperiodic paralysis. METHODS Over an 8-year period, patients with hypokalemic nonperiodic paralysis were enrolled by excluding those with hypokalemic periodic paralysis due to acute shift of K(+) into cells. Blood and spot urine samples were collected for the measurements of electrolytes, pH, and biochemistries. Intravenous potassium chloride (KCl) at a rate of 10-20 mmol/h was administered until muscle strength recovered. RESULTS We had identified 58 patients with hypokalemic nonperiodic paralysis from 208 consecutive patients with hypokalemic paralysis, and their average K(+) concentration was 1.8 ± 0.2 mmol/L. Among patients with low urinary K(+) excretion (n = 17), chronic alcoholism, remote diuretic use, and anorexia/bulimia nervosa were the most common causes. Among patients with high urinary K(+) excretion (n = 41) and metabolic acidosis, renal tubular acidosis and chronic toluene abuse were the main causes, while primary aldosteronism, Gitelman syndrome, and diuretics were the leading diagnoses with metabolic alkalosis. The average KCl dose needed to restore muscle strength was 3.8 ± 0.8 mmol/kg. Initial lower plasma K(+), volume depletion, and high urinary K(+) excretion were associated with higher recovery KCl dosage. During therapy, patients with paradoxical hypokalemia (n = 32) who required more KCl supplementation than patients without (4.1 ± 0.7 vs 3.4 ± 0.7 mmol/kg, P < 0.001) often exhibited significantly higher plasma renin activity and received a higher volume of normal saline before its appearance. CONCLUSIONS Understanding the common etiologies of hypokalemic nonperiodic paralysis may aid in early diagnosis. Patients with initial lower plasma K(+), renal K(+) wasting, and hypovolemia required higher recovery K(+) dosage. Paradoxical hypokalemia is prone to develop in hypovolemic patients even during K(+) supplementation with volume repletion.
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Affiliation(s)
- Chih-Chien Sung
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Chih-Jen Cheng
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Wen-Fang Chiang
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Department of Medicine, Armed Forces Taoyuan General Hospital, Taoyuan, Taiwan
| | - Tom Chau
- Department of Medicine, Providence St. Vincent Medical Center, Portland, Ore
| | - Yu-Juei Hsu
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Sung-Sen Yang
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Shih-Hua Lin
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.
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Hypokalemic paralysis in a young obese female. Clin Chim Acta 2012; 413:1295-7. [DOI: 10.1016/j.cca.2012.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Revised: 04/04/2012] [Accepted: 04/04/2012] [Indexed: 11/20/2022]
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Unwin RJ, Luft FC, Shirley DG. Pathophysiology and management of hypokalemia: a clinical perspective. Nat Rev Nephrol 2011; 7:75-84. [PMID: 21278718 DOI: 10.1038/nrneph.2010.175] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Potassium (K(+)) ions are the predominant intracellular cations. K(+) homeostasis depends on external balance (dietary intake [typically 100 mmol per day] versus excretion [95% via the kidney; 5% via the colon]) and internal balance (the distribution of K(+) between intracellular and extracellular fluid compartments). The uneven distribution of K(+) across cell membranes means that a mere 1% shift in its distribution can cause a 50% change in plasma K(+) concentration. Hormonal mechanisms (involving insulin, β-adrenergic agonists and aldosterone) modulate K(+) distribution by promoting rapid transfer of K(+) across the plasma membrane. Extrarenal K(+) losses from the body are usually small, but can be marked in individuals with chronic diarrhea, severe burns or prolonged sweating. Under normal circumstances, the kidney's distal nephron secretes K(+) and determines final urinary excretion. In patients with hypokalemia (plasma K(+) concentration <3.5 mmol/l), after the exclusion of extrarenal causes, alterations in sodium ion delivery to the distal nephron, mineralocorticoid status, or a specific inherited or acquired defect in distal nephron function (each of which affects distal nephron K(+) secretion), should be considered. Clinical management of hypokalemia should establish the underlying cause and alleviate the primary disorder. This Review aims to inform clinicians about the pathophysiology and appropriate treatment for hypokalemia.
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Affiliation(s)
- Robert J Unwin
- Centre for Nephrology, Royal Free Hospital, University College London, Rowland Hill Street, London NW3 2PF, UK.
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Lin SH, Yang SS, Chau T. A practical approach to genetic hypokalemia. Electrolyte Blood Press 2010; 8:38-50. [PMID: 21468196 PMCID: PMC3041498 DOI: 10.5049/ebp.2010.8.1.38] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 04/07/2010] [Indexed: 01/07/2023] Open
Abstract
Mutations in genes encoding ion channels, transporters, exchangers, and pumps in human tissues have been increasingly reported to cause hypokalemia. Assessment of history and blood pressure as well as the K+ excretion rate and blood acid-base status can help differentiate between acquired and inherited causes of hypokalemia. Familial periodic paralysis, Andersen's syndrome, congenital chloride-losing diarrhea, and cystic fibrosis are genetic causes of hypokalemia with low urine K+ excretion. With respect to a high rate of K+ excretion associated with faster Na+ disorders (mineralocorticoid excess states), glucoricoid-remediable aldosteronism and congenital adrenal hyperplasia due to either 11β-hydroxylase and 17α-hydroxylase deficiencies in the adrenal gland, and Liddle's syndrome and apparent mineralocorticoid excess in the kidney form the genetic causes. Among slow Cl- disorders (normal blood pressure, low extracellular fluid volume), Bartter's and Gitelman's syndrome are most common with hypochloremic metabolic alkalosis. Renal tubular acidosis caused by mutations in the basolateral Na+/HCO3- cotransporter (NBC1) in the proximal tubules, apical H+-ATPase pump, and basolateral Cl-/HCO3- exchanger (anion exchanger 1, AE1) in the distal tubules and carbonic anhydroase II in both are genetic causes with hyperchloremic metabolic acidosis. Further work on genetic causes of hypokalemia will not only provide a much better understanding of the underlying mechanisms, but also set the stage for development of novel therapies in the future.
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Affiliation(s)
- Shih-Hua Lin
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
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Lin SH. A Practical and Pathophysiologic Approach to Hypokalemia. Int J Organ Transplant Med 2008. [DOI: 10.1016/s1561-5413(08)60014-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Halperin ML, Kamel KS. Dynamic interactions between integrative physiology and molecular medicine: The key to understand the mechanism of action of aldo sterone in the kidney. Can J Physiol Pharmacol 2000. [DOI: 10.1139/y00-039] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our objective is to illustrate how an approach that integrates new insights from molecular biology and traditional physiology can lead to the development of new concepts. This dynamic interaction is illustrated by examining the steps taken to improve our understanding of the renal actions of aldosterone. We began by defining the big picture of what aldosterone does in the kidney. This led to the conclusion that aldosterone must at times become a sodium chloride-retaining hormone, while at other times it must function primarily or exclusively as a kaliuretic hormone. The second step was to define the major molecular actions of this hormone. Acting on the principal cells in the cortical collecting duct (CCD), aldosterone leads to the insertion of active epithelial sodium ion channels (ENaC) in their luminal membranes. This active ENaC, however, does not distinguish between the two major renal actions of aldosterone. Accordingly, we returned to integrative physiology and examined a possible role of renal and non-renal events. We implicated the potential importance of the delivery of bicarbonate ions to the CCD to determine which effect of aldosterone will become manifest. This, however, required that we reconsider some of the traditional views in interpretation of acid-base balance. At the clinical level, this global view can help us understand why, for example, a low dietary intake of potassium salts might predispose a person to an elevated blood pressure. Using a similar approach, it is possible to understand how the risk of the formation of kidney stones can be minimized.Key words: acid-base, hypertension, integrative physiology, kidney stones, potassium, sodium.
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Kamel KS, Quaggin S, Scheich A, Halperin ML. Disorders of potassium homeostasis: an approach based on pathophysiology. Am J Kidney Dis 1994; 24:597-613. [PMID: 7942818 DOI: 10.1016/s0272-6386(12)80220-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Disorders of potassium (K+) homeostasis are frequently encountered in clinical medicine and may have serious sequelae, particularly cardiac arrhythmias. Since long-term K+ balance depends on regulation of renal excretion of K+, the focus of this paper is to provide a novel way to analyze the K+ excretory process at the bedside in a noninvasive fashion. A fundamental aim was to incorporate recent new advances in K+ physiology to the clinical analysis of K+ disorders. In so doing, we have tried to replace eponyms and largely descriptive terms with more specific, but hypothetical pathophysiologic diagnoses. The approach we used focuses on an assessment of the components of K+ excretion in vivo. If the rate of excretion of K+ differs from the "expected" value for the stimulus of hypokalemia or hyperkalemia, one should determine whether the fault is with the flow rate and/or the [K+] in the terminal cortical collecting duct. The former is influenced primarily by the rate of excretion of osmoles when antidiuretic hormone acts, whereas the [K+] in the cortical collecting duct is determined by factors that modulate rate of electrogenic reabsorption of Na+ in that segment and its conductance for K+. By examining the extracellular fluid (ECF) volume status, the plasma renin activity, and the renal response to the induction of ECF volume contraction, we attempted to deduce whether the change in electrogenic reabsorption of Na+ was due to an altered Na+ transport or apparent permeability to chloride in the cortical collecting duct. We believe that an approach which draws heavily on pathophysiology can be of practical use at the bedside and, in addition, indicate areas in which more research could be fruitful. To illustrate these points, two clinical cases with hypokalemia and two with hyperkalemia were analyzed. Nevertheless, it is important to emphasize that the approach provided is speculative.
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Affiliation(s)
- K S Kamel
- Renal Division, St Michael's Hospital, University of Toronto, Canada
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