What is the role of electrolyte level measurement in the workup of pediatric adrenal insufficiency (Addison disease)?

Updated: Dec 07, 2018
  • Author: Kimberly Tafuri, DO; Chief Editor: Sasigarn A Bowden, MD  more...
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Answer

Hyponatremia with or without hyperkalemia is common in patients with primary adrenal insufficiency (Addison disease), and it is due to deficient aldosterone secretion. Hyponatremia is occasionally found in patients with central or secondary adrenal insufficiency. The presumed cause is water retention due to increased secretion of vasopressin. [43]

When hyponatremia or hyperkalemia is present, a simultaneous serum sample and spot urine or 24-hour urine measurement of sodium, potassium, and creatinine concentrations can be used to calculate the fractional excretion of sodium to determine whether inappropriate natriuresis is occurring (see Medscape Reference Laboratory Medicine articles Serum Sodium, Urine Sodium, Potassium, and Creatinine). A plasma renin activity (PRA)–to–aldosterone ratio of more than 30 is suggestive of inadequate mineralocorticoid production.


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