Normal Reference Ranges
Adult
20 - 220 (highly diet-dependent) mEq/L
Pediatric
Same as adult mEq/L
Clinical Significance
Used to differentiate prerenal AKI (< 20 mEq/L due to conservation) from intrinsic renal AKI (> 40 mEq/L due to impaired tubular reabsorption).
Causes of High
- Acute Tubular Necrosis (ATN) (typically > 40 mEq/L)
- SIADH
- Adrenal insufficiency
- Diuretic use
Causes of Low
- Prerenal acute kidney injury (typically < 20 mEq/L)
- Dehydration
- Heart failure
- Cirrhosis / Nephrotic syndrome