Original URL http://www.emedicine.com/emerg/topic273.htm Hypokalemia Last Updated: September 20, 2005 Rate this Article Email to a Colleague Get CME/CE for article Synonyms and related keywords: potassium level less than 3.5 mEq/L, potassium homeostasis, palpitations, skeletal muscle weakness, cramping, paralysis, paresthesias, abdominal cramping, ventricular arrhythmias, premature atrial beats, premature ventricular beats, respiratory distress, hypoventilation, respiratory failure, lethargy, fasciculations, tetany, decreased tendon reflexes, cushingoid appearance, hyperaldosteronism, magnesium depletion, ileal loop, diuretics, alkalosis, low potassium AUTHOR INFORMATION Section 1 of 11 Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Author: David Garth, MD, Consulting Staff, Department of Emergency Medicine, Mary Washington Hospital David Garth, MD, is a member of the following medical societies: American Academy of Emergency Medicine Editor(s): Robin R Hemphill, MD, MPH, Associate Professor, Director, Disaster Preparedness, Department of Emergency Medicine, Vanderbilt University Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Howard A Bessen, MD, Professor of Medicine, UCLA School of Medicine; Program Director, Department of Emergency Medicine, Harbor-UCLA Medical Center; John Halamka, MD, Chief Information Officer, CareGroup Healthcare System, Assistant Professor of Medicine, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Assistant Professor of Medicine, Harvard Medical School; and Craig Feied, MD, FACEP, FAAEM, FACPh, Professor of Emergency Medicine, Georgetown University, Director, National Institute for Medical Informatics, Director, Federal Project ER One, Director, National Center for Emergency Medicine Informatics Disclosure INTRODUCTION Section 2 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Background: Potassium is one of the body's major ions. Nearly 98% of the body's potassium is intracellular. The ratio of intracellular to extracellular potassium is important in determining the cellular membrane potential. Small changes in the extracellular potassium level can have profound effects on the function of the cardiovascular and neuromuscular systems. The kidney determines potassium homeostasis, and excess potassium is excreted in the urine. The reference range for serum potassium level is 3.5-5 mEq/L, with total body potassium stores of approximately 50 mEq/kg (ie, approximately 3500 mEq in a 70-kg person). Hypokalemia is defined as a potassium level less than 3.5 mEq/L. Moderate hypokalemia is a serum level of 2.5-3 mEq/L. Severe hypokalemia is defined as a level less than 2.5 mEq/L. Pathophysiology: Hypokalemia may result from conditions as varied as renal or GI losses, inadequate diet, transcellular shift (movement of potassium from serum into cells), and medications. Frequency: * In the US: As many as 20% of hospitalized patients are hypokalemic; however, hypokalemia is clinically significant in only about 4-5% of these patients. Severe hypokalemia is relatively uncommon. Up to 14% of outpatients are mildly hypokalemic, while approximately 80% of patients who are receiving diuretics become hypokalemic. Sex: Incidence is equal in males and females. CLINICAL Section 3 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography History: The history may be vague. Hypokalemia should be suggested by a constellation of symptoms that involve the GI, renal, musculoskeletal, cardiac, and nervous systems. The patient's medications should be reviewed to ascertain whether any of them could cause hypokalemia. Common symptoms include the following: * Palpitations * Skeletal muscle weakness or cramping * Paralysis, paresthesias * Constipation * Nausea or vomiting * Abdominal cramping * Polyuria, nocturia, or polydipsia * Psychosis, delirium, or hallucinations * Depression Physical: Findings may include the following: * Signs of ileus * Hypotension * Ventricular arrhythmias * Cardiac arrest * Bradycardia or tachycardia * Premature atrial or ventricular beats * Hypoventilation, respiratory distress * Respiratory failure * Lethargy or other mental status changes * Decreased muscle strength, fasciculations, or tetany * Decreased tendon reflexes * Cushingoid appearance (eg, edema) Causes: * Renal losses o Renal tubular acidosis o Hyperaldosteronism o Magnesium depletion o Leukemia (mechanism uncertain) * GI losses o Vomiting or nasogastric suctioning o Diarrhea o Enemas or laxative use o Ileal loop * Medication effects o Diuretics (most common cause) o Beta-adrenergic agonists o Steroids o Theophylline o Aminoglycosides * Transcellular shift o Insulin o Alkalosis * Malnutrition or decreased dietary intake, parenteral nutrition DIFFERENTIALS Section 4 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Cushing Syndrome Hypocalcemia Hypomagnesemia Other Problems to be Considered: Medication side effect Renal tubular acidosis Quick Find Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Click for related images. Related Articles Cushing Syndrome Hypocalcemia Hypomagnesemia Continuing Education CME available for this topic. Click here to take this CME. Patient Education Endocrine System Center Low Potassium Overview Low Potassium Causes Low Potassium Symptoms Low Potassium Treatment Important Safety Information Rozerem™ (ramelteon) is indicated for the treatment of insomnia characterized by difficulty with sleep onset. Rozerem can be prescribed for long-term use. Rozerem should not be used in patients with hypersensitivity to any components of the formulation, severe hepatic impairment, or in combination with fluvoxamine. Failure of insomnia to remit after a reasonable period of time should be medically evaluated, as this may be the result of an unrecognized underlying medical disorder. Hypnotics should be administered with caution to patients exhibiting signs and symptoms of depression. Rozerem has not been studied in patients with severe sleep apnea, severe COPD, or in children or adolescents. The effects in these populations are unknown. Avoid taking Rozere with alcohol. Rozerem has been associated with decreased testosterone levels and increased prolactin levels. Health professionals should be mindful of any unexplained symptoms possibly associated with such changes in these hormone levels. Rozerem should not be taken with or immediately after a high-fat meal. Rozerem should be taken within 30 minutes before going to bed and activities confined to preparing for bed. The most common adverse events seen with Rozerem that had at least a 2% incidence difference from placebo were somnolence, dizziness, and fatigue. (Advertisement) (Advertisement) WORKUP Section 5 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Lab Studies: * Serum potassium level <3.5 mEq/L (3.5 mmol/L) * BUN and creatinine * Glucose, magnesium, calcium, and/or phosphorous if coexistent electrolyte disturbances are suspected. * Consider digoxin level if the patient is on a digitalis preparation; hypokalemia can potentiate digitalis-induced arrhythmias. * Consider arterial blood gases (ABG): Alkalosis can cause potassium to shift from extracellular to intracellular. Imaging Studies: * CT scan of the adrenal glands is indicated if mineralocorticoid excess is evident (rarely needed emergently). Other Tests: * Electrocardiogram o T- wave flattening or inverted T waves o Prominent U wave that appears as QT prolongation (see Picture 1) o ST segment depression o Ventricular arrhythmias (eg, premature ventricular contractions [PVCs], torsade de pointes, ventricular fibrillation) o Atrial arrhythmias (eg, premature atrial contractions [PACs], atrial fibrillation) TREATMENT Section 6 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Prehospital Care: Be attentive to the ABCs. * If the patient is severely bradycardic or manifesting cardiac arrhythmias, appropriate pharmacologic therapy or cardiac pacing should be considered. Emergency Department Care: * Patients in whom severe hypokalemia is suspected should be placed on a cardiac monitor; establish intravenous (IV) access and assess respiratory status. * Direct potassium replacement therapy by the symptomatology and the potassium level. Begin therapy after laboratory confirmation of the diagnosis. * Usually, patients who have mild or moderate hypokalemia (potassium of 2.5-3.5 mEq/L), are asymptomatic, or have only minor symptoms need only oral potassium replacement therapy. If cardiac arrhythmias or significant symptoms are present, then more aggressive therapy is warranted. This treatment is similar to the treatment for severe hypokalemia. * If the potassium level is less than 2.5 mEq/L, IV potassium should be given. Admission or ED observation is indicated; replacement therapy takes more than a few hours. * Serum potassium is difficult to replenish if serum magnesium is also low. Look to replace both. Consultations: An internist or a nephrologist should be consulted for admission or follow-up care. MEDICATION Section 7 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Oral is the preferred route for potassium repletion because it is easy to administer, safe, inexpensive, and readily absorbed from the GI tract. For patients with mild hypokalemia and minimal symptoms, oral replacement is sufficient. For patients who have severe hypokalemia and are symptomatic, both IV and oral replacement are necessary. While IV potassium dosages of up to 40 mEq/h have been advocated, patients should receive no more than 20 mEq/h IV to avoid potential deleterious effects on the cardiac conduction system. Potassium solutions should never be given as an IV push and should be administered as a dilute solution. Higher concentrations of IV potassium are damaging to the smaller peripheral veins. Drug Category: Electrolyte supplements -- Potassium is essential for transmission of nerve impulses, contraction of cardiac muscle, maintenance of intracellular tonicity, skeletal and smooth muscles, and maintenance of normal renal function. These agents increase the body's potassium level. In general, 1 mEq/L drop in potassium correlates to a loss of 100-200 mEq of total body potassium. Hypokalemia may result from the movement of potassium into cells without loss of potassium from the body. Drug Name Potassium chloride, IV -- Potassium depletion sufficient to cause 1 mEq/L drop in serum potassium requires loss of about 100-200 mEq of potassium from total body store. In symptomatic patient with severe hypokalemia, administer up to 40 mEq/h of this IV preparation; maintain close follow-up care, provide continuous ECG monitoring, and check serial potassium levels. Higher dosages may increase risk of cardiac complications. Many institutions have policies that limit maximum amount of potassium that can be given per hour. Adult Dose 10-20 mEq/h IV via peripheral or central line Pediatric Dose 0.5-1 mEq/kg/dose over 1 h; not to exceed adult maximum dose Contraindications Hyperkalemia; renal failure; conditions in which potassium is retained; oliguria or azotemia; crush syndrome; severe hemolytic reactions; anuria; adrenocortical insufficiency Interactions Concurrent ACE inhibitors may result in elevated serum potassium concentrations; concurrent potassium-sparing diuretics or potassium-containing salt substitutes can produce severe hyperkalemia; in patients taking digoxin, hypokalemia may result in digoxin toxicity—caution if discontinuing potassium administration in patients maintained on digoxin Pregnancy A - Safe in pregnancy Precautions Do not infuse rapidly; high plasma concentrations of potassium may cause death due to cardiac depression, arrhythmias, or arrest; plasma levels do not necessarily reflect tissue levels; monitor potassium replacement therapy whenever possible by continuous or serial ECGs; when concentration >40 mEq/L infused, local pain and phlebitis may occur Drug Name Potassium chloride, oral (Klor-Con, K-Dur) -- Potassium depletion sufficient to cause 1 mEq/L drop in serum potassium requires a loss of about 100-200 mEq of potassium from total body store. Available in liquid, powder, or tablet form. Any form may irritate the stomach and cause vomiting. Should be taken with food or after meals to minimize GI discomfort. Oral potassium preparations include 8 mEq KCI slow release tablets, 20 mEq KCI elixir, 20 mEq KCI powder, 25 mEq KCI tablet. Adult Dose 20-40 mEq PO bid/qid; not to exceed 40 mEq PO/dose Pediatric Dose 1-4 mEq/kg/24 h PO divided bid/qid Contraindications Hyperkalemia; renal failure; conditions in which potassium is retained; oliguria or azotemia; crush syndrome; severe hemolytic reactions; anuria; adrenocortical insufficiency Interactions Concurrent ACE inhibitors may elevate serum potassium concentrations; concurrent potassium-sparing diuretics or potassium-containing salt substitutes can produce severe hyperkalemia; in patients taking digoxin, hypokalemia may result in digoxin toxicity—caution if discontinuing potassium administration in patients maintained on digoxin Pregnancy A - Safe in pregnancy Precautions Caution in cardiac disease and renal impairment; plasma levels do not necessarily reflect tissue levels FOLLOW-UP Section 8 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Further Inpatient Care: * Continue IV replacement of potassium as needed. * Continue cardiac monitoring in severe hypokalemia. * Repeat potassium level measurement every 1-3 hours. * Identify the etiology of the hypokalemia. Further Outpatient Care: * Repeat potassium level in 2-3 days. In/Out Patient Meds: * Consider switching to potassium-sparing diuretic if diuretic therapy is needed. * Take 40 mEq KCI daily for 2-3 days and repeat the potassium level. Transfer: * Patients should be transferred only after any cardiac arrhythmias have been treated and the condition has been stabilized. * Depending on the level of hypokalemia, an advanced cardiac life support (ACLS) ambulance should be used to allow continuous cardiac monitoring during transport. Complications: * Replacing potassium too quickly can cause a rapid rise in the blood potassium level, leading to a relative hyperkalemia with subsequent cardiac complications. * If hypokalemia is not corrected easily with replacement therapy, search for other coexistent metabolic abnormalities (eg, hypomagnesemia). Hypokalemia may be refractory to treatment until hypomagnesemia is corrected. * Hypokalemia can potentiate digitalis toxicity in patients who are taking digoxin. Prognosis: * Hypokalemia usually resolves with appropriate therapy. Patient Education: * Diet modification is recommended for those patients who are predisposed to hypokalemia. Increase intake of bananas, tomatoes, oranges, and peaches because they are high in potassium. * For excellent patient education resources, visit eMedicine's Endocrine System Center. Also, see eMedicine's patient education article Low Potassium. MISCELLANEOUS Section 9 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Medical/Legal Pitfalls: * If potassium is replaced too quickly, the rapid rise of the serum potassium level can induce symptomatic hyperkalemia; however, the total body reserves of potassium might still be less than normal. * Failure to monitor and repeat potassium levels during replacement therapy * Failure to recognize and correct other coexistent metabolic disorders (eg, hypomagnesemia) Special Concerns: * Do not overcorrect potassium in patients with periodic hypokalemic paralysis. This condition is a transcellular maldistribution, not a true deficit. * Diuretic therapy, diarrhea, and chronic laxative abuse are the most common causes of hypokalemia in elderly patients. * In patients with hypokalemia and diabetic ketoacidosis, part of the serum potassium should be administered as potassium phosphate. PICTURES Section 10 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Click here to go to the next section in this topic Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography Caption: Picture 1. Prominent U waves after the T waves in hypokalemia Click to see larger picture Click to see detailView Full Size Image Click to ZoomeMedicine Zoom View (Interactive!) Picture Type: ECG BIBLIOGRAPHY Section 11 of 11 Click here to go to the previous section in this topic Click here to go to the top of this page Author Information Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Pictures Bibliography * Cohn JN, Kowey PR, Whelton PK: New guidelines for potassium replacement in clinical practice: a contemporary review by the National Council on Potassium in Clinical Practice. Arch Intern Med 2000 Sep 11; 160(16): 2429-36[Medline]. * Dominiczak AF, Semple PF, Fraser R, et al: Hypokalaemia in alcoholics. Scott Med J 1989 Aug; 34(4): 489-94[Medline]. * Gennari FJ: Hypokalemia. N Engl J Med 1998 Aug 13; 339(7): 451-8[Medline]. * Halperin ML, Kamel KS: Potassium. Lancet 1998 Jul 11; 352(9122): 135-40[Medline]. * Howes LG: Which drugs affect potassium? Drug Saf 1995 Apr; 12(4): 240-4[Medline]. * Kleinfeld M, Borra S, Gavani S, et al: Hypokalemia: are elderly females more vulnerable?. J Natl Med Assoc 1993 Nov; 85(11): 861-4[Medline]. * Kung M: Parenteral adrenergic bronchodilators and potassium. Chest 1986 Mar; 89(3): 322-3[Medline]. * Latronico N, Shehu I, Seghelini E: Neuromuscular sequelae of critical illness. Curr Opin Crit Care 2005 Aug; 11(4): 381-90[Medline]. * Mandal AK: Hypokalemia and hyperkalemia. Med Clin North Am 1997 May; 81(3): 611-39[Medline]. * Paice BJ, Paterson KR, Onyanga-Omara F, et al: Record linkage study of hypokalaemia in hospitalized patients. Postgrad Med J 1986 Mar; 62(725): 187-91[Medline]. * Reactions Weekly: Dextrose: First report of ventricular arrhythmia: case report. Reactions Weekly 2005; 1046: 11. * Seigel JD, Di Palma JA: Medical treatment of constipation. Clinics in Colon & Rectal Surgery 2005; 18(2): 76-80. * Singhal PC, Venkatesan J, Gibbons N, et al: Prevalence and predictors of rhabdomyolysis in patients with hypokalemia. N Engl J Med 1990 Nov 22; 323(21): 1488[Medline]. * Walters EG, Barnes IC: A survey of hypokalaemia in patients of general practitioners. Br J Clin Pract 1988 May; 42(5): 192-5[Medline]. * Zafar H, Rehmani R, Chawla T, et al: Suicidal bus bombing of French Nationals in Pakistan: physical injuries and management of survivors. Eur J Emerg Med 2005 Aug; 12(4): 163-7[Medline]. * Zull DN: Disorders of potassium metabolism. Emerg Med Clin North Am 1989 Nov; 7(4): 771-94[Medline]. NOTE: Medicine is a constantly changing science and not all therapies are clearly established. New research changes drug and treatment therapies daily. The authors, editors, and publisher of this journal have used their best efforts to provide information that is up-to-date and accurate and is generally accepted within medical standards at the time of publication. However, as medical science is constantly changing and human error is always possible, the authors, editors, and publisher or any other party involved with the publication of this article do not warrant the information in this article is accurate or complete, nor are they responsible for omissions or errors in the article or for the results of using this information. The reader should confirm the information in this article from other sources prior to use. In particular, all drug doses, indications, and contraindications should be confirmed in the package insert. FULL DISCLAIMER Hypokalemia excerpt About Us | Privacy | Terms of Use | Contact Us | Advertising | Institutional Subscribers We subscribe to the HONcode principles of the Health On the Net Foundation © 1996-2006 by WebMD All Rights Reserved