Elevated Urine Osmolality

An increased urine osmolality above the expected reference range (normal random specimen: ~50-1,200 mOsm/kg; elevated: >850 mOsm/kg), indicating abnormally concentrated urine due to increased renal water conservation.

Causes

• Dehydration: Reduced fluid intake or excessive fluid loss (vomiting, diarrhea, sweating)

• Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

• Adrenal insufficiency

• Hyperglycemia with osmotic diuresis

• High-protein diet

• Kidney failure