A Practical and Pathophysiologic Approach to Hypokalemia
Article Outline
Hypokalemia is not an isolated disease but an associated finding in a vast number of different diseases; it poses a great challenge in correct diagnosis and proper management. Hypokalemia usually arises from a shift of potassium (K+) into cells and/or a net loss of K+. Besides a detailed history and physical examination, measurement of K+ excretion rate with freshly-voided and/or 24-hour urine and assessment of blood acid-base status can help discriminate between the various causes of hypokalemia. In patients with a low rate of K+ excretion, hypokalemia can be due to an acute shift of K+ into cells, intestinal/sweating K+ loss, or prior renal K+ excretion. In patients with a high rate of K+ excretion, there may be either increased flow rate or increased K+ secretion, seen with fast sodium (Na+) or slow chloride (Cl−) disorders, in the cortical collecting ducts (CCD). An increased flow rate in the CCD arises from increased osmole excretion (whether solutes or electrolytes). Patients with fast Na+ disorders have a high extracellular fluid (ECF) volume and thus high blood pressure associated with a state of high mineralocorticoid activity. Measurement of renin activity, aldosterone, and cortisol levels in plasma helps distinguish between the causes. Patients with slow Cl− disorders usually have low to normal ECF volume and blood pressure and are usually associated with abnormal acid-base states. In patients with metabolic alkalosis, urine Na+ and Cl− excretion rate reveal the basis for renal Na+ wasting and distinguish it from non-renal Na+ loss. In patients with hyperchloremic metabolic acidosis, an assessment of the ammonium excretion rate (NH4+) separates those with renal tubular acidosis (low NH4+ excretion) from those with other causes. The treatment of hypokalemia depends on the degree and timing of hypokalemia, clinical manifestations, underlying causes, and potential risks from associated conditions.
Key words: acid-base , aldosterone , ammonium , blood pressure , hypokalemia , renin , urine electrolyte
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References
- . Hypokalemia and arrhythmias . Am J Med . 1986;80:13–22
- . The cardiovascular implications of hypokalemia . Am J Kidney Dis . 2005;45:233–247
- . Severe hypokalemia in a Chinese male . QJM . 2002;95:695–704
- . Effects of electrolyte disorders on renal structure and function . N Engl J Med . 1967;276:383–389
- . Metabolic and renal studies in chronic potassium depletion resulting from overdose of laxatives . J Clin Invest . 1953;32:258–271
- . Symptoms and course of chronic hypokalemic nephropathy in man . Clin Nephrol . 1977;17:654–657
- . Potassium homeostasis and clinical implications . Am J Med . 1984;77:3–10
- . Hypokalemia and hyperkalemia . Med Clin North Am . 1997;81:611–639
- . Hypokalemia—consequences, causes, and correction . J Am Soc Nephrol . 1997;8:1179–1188
- . Potassium . Lancet . 1998;352:135–140
- . Hypokalemia . N Engl J Med . 1998;339:451–458
- . Hypokalemia: a practical approach to diagnosis and its genetic basis . Curr Med Chem . 2007;14:1551–1565
- . Internal potassium balance and the control of the plasma potassium concentration . Medicine . 1981;60:339–354
- . Renal and extrarenal regulation of potassium . Kidney Int . 2007;72:397–410
- . Clinical and therapeutic significance of the Na+, K+pump . Clin Sci . 1998;95:3–17
- . The mechanism of insulin stimulation of (Na+,K+)-ATPase . J Biol Chem . 1985;260:6206–6212
- . Insulin-induced cytoplasmic alkalinization and glucose transport in muscle cells . Am J Physiol . 1986;250:C720–C728
- . Potassium channels: molecular defects, diseases, and therapeutic opportunities . Pharmacol Rev . 2000;52:557–594
- . Molecular diversity and regulation of renal potassium channels . Physiol Rev . 2005;85:319–371
- . Hypokalemia and the pathology of ion transport molecules . Semin Nephrol . 1998;18:31–45
- . Renal potassium transport: mechanisms and regulation . Am J Physiol . 1998;274:F817–F833
- . What is responsible for the diurnal variation in potassium excretion? . Am J Physiol . 1994;267:R554–R560
- . The effects of antidiuretic hormone and state of potassium balance on the renin-angiotensin system in rats with diabetes insipidus . J Physiol . 1982;323:519–531
- . Urinary concentrating ability and antidiuretic hormone responsiveness in the potassium-depleted dog . J Lab Clin Med . 1982;100:53–60
- . Control of excretion of potassium: lessons from studies during prolonged total fasting in human subjects . Am J Physiol . 1997;273:796–800
- . Regulation of the epithelial Na+ channel by aldosterone: open questions and emerging answers . Kidney Int . 2000;57:1270–1276
- Development of a test to evaluate the transtubular potassium concentration gradient in the cortical collecting duct in vivo . Miner Electrolyte Metab . 1986;12:226–233
- . Disorders of potassium homeostasis: an approach based on pathophysiology . Am J Kidney Dis . 1994;24:597–613
- . Regulation of ROMK (Kir1.1) channels: new mechanisms and aspects . Am J Physiol . 2006;290:F14–F19
- . BK channels in the kidney: role in K+secretion and localization of molecular components . Am J Physiol . 2006;291:F517–F529
- Transient neonatal hyperkalemia in the antenatal (ROMK defective) Bartter syndrome . J Pediatr . 2003;142:318–323
- Maxi-K+ channels contribute to urinary potassium excretion in the ROMK-deficient mouse model of Type II Bartter's syndrome and in adaptation to a high-K+ diet . Kidney Int . 2006;70:51–59
- . Diagnostic strategies in disorders of fluid, electrolyte and acid-base homeostasis . Am J Med . 1982;72:496–520
- . Urine electrolytes and osmolality: when and how to use them . Am J Nephrol . 1990;10:89–102
- . Approach to the patients with a severe degree of hypokalemia: the potassium quiz . QJM . 2005;98:305–316
- . Fractional excretion of potassium in normal subjects and in patients with hypokalemia . Postgrad Med J . 1995;71:211–212
- . Possible mechanisms to explain the absence of hyperkalemia in Addison's disease . Nephrol Dial Transplant . 2001;16:1280–1284
- . Laboratory tests to determine the causes for hypokalemia and paralysis . Arch Intern Med . 2004;164:1561–1566
- . An approach to the patient with severe hypokalemia . QJM . 2005;98:305–316
- . Hypokalemia from beta2-receptor stimulation by circulating epinephrine . N Engl J Med . 1983;309:1414–1419
- . Unusual cases of hypokalemia and paralysis . QJM . 2006;99:181–192
- . Acute barium poisoning treated with hemodialysis . Am J Emerg Med . 2001;19:175–177
- . Hypokalemia related to acute chloroquine ingestion . Lancet . 1995;346:877–880
- . Hypokalemia and paralysis . QJM . 2001;94:133–139
- . Thyrotoxic periodic paralysis . Mayo Clin Proc . 2005;80:99–105
- . Thyrotoxic periodic paralysis: a diagnostic challenge . J Clin Endocrinol Metab . 2006;91:2490–2495
- . Skeletal muscle dihydropyridine-sensitive calcium channel gene mutations in Chinese patients with hypokalemic periodic paralysis . Am J Med Sci . 2005;329:66–70
- The primary periodic paralyses: diagnosis, pathogenesis and treatment . Brain . 2006;129:8–17
- . Pathophysiology of potassium absorption and secretion by the human intestine . Gastroenterology . 1994;107:548–571
- . The change in electrolytes and acid-base after artificially induced acute diarrhea by laxatives . J Korean Med Sci . 1994;9:388–393
- . A puzzling cause of hypokalemia . Lancet . 2002;360:224
- . A simple and rapid approach to hypokalemic paralysis . Am J Emerg Med . 2003;21:487–491
- . Primary aldosteronism: renaissance of a syndrome . Clin Endocrinol . 2007;66:607–618
- . A hidden cause of hypokalemic paralysis in a patient with prostate cancer . Support Care Cancer . 2004;12:810–812
- . Life-threatening hypokalemia in an asthmatic patient treated with high-dose hydrocortisone . Am J Med Sci . 2004;327:152–155
- . Ectopic ACTH syndrome associated with large cell neuroendocrine carcinoma of lung . Am J Med Sci . 2007;334:487–489
- . Diagnosis and management of congenital adrenal hyperplasia . Ann Rev Med . 1998;49:311–328
- . Liddle's syndrome . Am J Med . 1998;104:301–309
- . Human hypertension caused by mutations in the kidney isozyme of 11 beta-hydroxysteroid dehydrogenase . Nat Genet . 1995;10:394–399
- . An unusual cause of hypokalemic paralysis: chronic licorice ingestion . Am J Med Sci . 2003;325:153–156
- . Aldosterone and other mineralocorticoids in Bartter's syndrome . J Lab Clin Med . 1984;103:848–853
- . Control of hydrogen ion homeostasis and renal acidosis . Medicine . 1971;50:503–541
- A new classification for renal defects in net acid excretion . Am J Kidney Dis . 1997;29:136–146
- . Glue-sniffing and distal renal tubular acidosis: sticking to the facts . J Am Soc Nephrol . 1991;1:1019–1027
- . Diffuse bone pain in a young women . Lancet . 2004;364:1910
- . Flaccid quadriparesis with Yersinia enterocolitis-induced hypokalemia . Arch Intern Med . 1989;149:1193–1194
- Severe metabolic acidosis and hypokalemia in a patient with enterovesical fistula . Clin Exp Nephrol . 2007;11:225–229
- . Cystic fibrosis presenting with hypokalemia and metabolic alkalosis in a previously healthy adolescent . J Am Soc Nephrol . 1997;8:352–355
- . Hypokalemia in the “beautiful people” . Am J Med . 1990;88:534–536
- Clinical presentation of genetically defined patients with hypokalemic salt-losing tubulopathies . Am J Med . 2002;112:183–190
- . Phenotype and genotype analysis in Chinese patients with Gitelman's syndrome . J Clin Endocrinol Metab . 2005;90:2500–2507
- . Acquired Bartter-like syndrome associated with gentamicin administration . Am J Med Sci . 2005;329:144–149
- . Intrafamilial phenotype variability in patients with Gitelman syndrome having the same mutations in their thiazide-sensitive sodium/chloride cotransporter . Am J Kidney Dis . 2004;443:304–312
- Use of calcium excretion values to distinguish two forms of primary renal tubular hypokalemic alkalosis: Bartter and Gitelman syndromes . J Pediatr . 1992;120:38–43
- . Gitelman's syndrome: from clinic to gene . Acta Nephrologica . 2003;17:113–120
- Normal prostaglandinuria E2 in Gitelman's syndrome, the hypocalciuric variant of Bartter's syndrome . Am J Kidney Dis . 1995;25:824–828
- Role of c yclooxygenase-2 in hyperprostaglandin E syndrome/antenatal Bartter syndrome . Kidney Int . 2002;62:253–260
- . New guidelines for potassium replacement in clinical practice: a contemporary review by the National Council on Potassium in Clinical Practice . Arch Intern Med . 2000;160:2429–2436
- . Decrease in serum potassium concentration and appearance of cardiac arrhythmia during infusion of potassium with glucose in potassium depleted patients . N Engl J Med . 1962;266:288–296
- . Diabetic ketoacidosis . Rev Endocr Metab Disord . 2003;4:159–166
- . Regulation of renal K+ transport by dietary K intake . Annu Rev Physiol . 2004;66:547–569
- . Hyperkalemia in the elderly: drugs exacerbate impaired potassium homeostasis . J Gen Intern Med . 1997;12:646–656
- . Hypokalemia and subsequent hyperkalemia in hospitalized patients . Nephrol Dial Transplant . 2007;22:3471–3477
- . Effects of potassium supplementation on the recovery of thyrotoxic periodic paralysis . Am J Emerg Med . 2004;22:544–547
- . Clinical and metabolic features of thyrotoxic periodic paralysis in 24 episodes . Arch Intern Med . 1999;159:601–606
- . Propranolol rapidly terminates the hypokalemia, hypophosphatemia and paralysis in thyrotoxic periodic paralysis . Am J Kidney Dis . 2001;37:620–623
- . Thyrotoxic periodic paralysis terminated with intravenous propranolol . Ann Emerg Med . 1994;24:736–740
- . Thyrotoxicosis and periodic paralysis: improvement with beta blockade . Ann Intern Med . 1974;81:332–336
- . Osmotic demyelination syndrome following correction of chronic hyponatremia with normal saline . Am J Med Sci . 2002;323:259–262
- . Osmotic demyelination syndrome following correction of hyponatremia: association with hypokalemia . Am J Med . 1994;96:408–413
- Osmotic demyelination syndrome: a potentially avoidable disaster . QJM . 2003;96:935–947
- . Diuretic-induced hypokalemia . Am J Med . 1984;77:18–27
- . Magnesium depletion as a cause of refractory potassium repletion . Arch Intern Med . 1985;149:186–189
- . Mechanism of negative potassium balance in the magnesium-deficient rat . Proc Soc Exp Biol Med . 1981;168:382–388
- . Electrostatic tuning of Mg2+ affinity in an inward-rectifier K+ channel . Science . 1994;371:243–245
- . Mechanism of hypokalemia in magnesium deficiency . J Am Soc Nephrol . 2007;18:2649–2652
- . Effect of potassium magnesium citrate on thiazide-induced hypokalemia and magnesium loss . Am J Kidney Dis . 1999;34:107–113
- . The plasma potassium concentration in metabolic acidosis; a re-evaluation . Am J Kidney Dis . 1988;11:220–224
- . Regulation of the apical K+ channels in the rat cortical collecting tubule during changes in K+ intake . Am J Physiol . 1999;277:F805–F812
- . Requirement for a high rate of potassium excretion in rats consuming a low electrolyte diet . J Physiol . 2006;572:493–501
PII: S1561-5413(08)60014-9
doi:10.1016/S1561-5413(08)60014-9
© 2008 The Hong Kong Society of Nephrology. Published by Elsevier Inc. All rights reserved.
