Hypokalemia in children
- Michael J Somers, MD
Michael J Somers, MD
- Associate Professor of Pediatrics
- Harvard Medical School
- Avram Z Traum, MD
Avram Z Traum, MD
- Instructor of Pediatrics
- Harvard Medical School
Hypokalemia is defined as a serum or plasma potassium that is less than the normal value. Most reference laboratories establish the lower pediatric limit of normal serum potassium between 3 and 3.5 mEq/L. However, symptoms are unlikely to occur in most healthy children until serum potassium is below 3 mEq/L.
The etiology, clinical findings, diagnosis, evaluation, and management of pediatric hypokalemia are reviewed here. Hypokalemia in adults is discussed separately. (See "Clinical manifestations and treatment of hypokalemia in adults" and "Causes of hypokalemia in adults" and "Evaluation of the adult patient with hypokalemia".)
Hypokalemia is relatively common among hospitalized pediatric patients, especially those who are critically ill [1-3]. In one study of 667 children cared for in a single-center pediatric intensive care unit in the United States during the calendar year 2006, 40 percent of the patients had a serum potassium level below 3.5 mEq/L . This included patients with severe hypokalemia, defined as potassium level less than 2.5 mEq/L (4 percent); moderate hypokalemia, defined as potassium level 2.5 to less than 3 mEq/L (12 percent); and mild hypokalemia, defined as potassium level from 3 to less than 3.5 mEq/L (24 percent). Hypokalemia was associated with diagnoses of cardiac disease, renal failure, or shock .
In developing countries, severe hypokalemia (potassium level <2.5 mEq/L) is often observed in children with diarrhea and severe acute malnutrition, and is associated with an increased risk of mortality .
POTASSIUM BALANCE AND LEVELS
Definition — Potassium is primarily an intracellular cation with cells containing approximately 98 percent of total body potassium. Hypokalemia is defined as serum level below the normal value, which is usually defined as 3.5 mEq/L.
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- POTASSIUM BALANCE AND LEVELS
- Homeostatic mechanisms
- Pathogenesis of hypokalemia
- Decreased intake
- Increased intracellular uptake
- - Alkalosis
- - Increased insulin activity
- - Elevated beta-adrenergic activity
- - Hypokalemic periodic paralysis
- - Other drugs (besides beta-adrenergic agonists)
- Gastrointestinal losses
- Increased urinary losses
- - Increased distal delivery of sodium and water
- Nonreabsorbable ions
- Osmotic diuresis
- Genetic tubular disorders
- Tubular injury
- - Distal (type 1) renal tubular acidosis (RTA)
- - Increased mineralocorticoid activity
- Other etiologies
- - Other causes of urinary loss
- Amphotericin B nephrotoxicity
- Liddle syndrome
- Cystic fibrosis and skin losses
- CLINICAL MANIFESTATIONS
- Muscular weakness
- Cardiac findings
- Renal manifestations
- DIFFERENTIAL DIAGNOSIS
- EVALUATION TO DETERMINE UNDERLYING ETIOLOGY
- Physical examination
- Laboratory studies
- - Urinary potassium excretion
- - Further evaluation
- Potassium supplementation
- - Route
- - Formulation
- - Our approach based on severity
- Other interventions
- - Magnesium depletion
- - Potassium-sparing diuretics
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS