Measures urine concentration, reflecting hydration and renal concentrating ability. Normal range: 1.003–1.030.

Clinical interpretation:

• High: Dehydration, glucosuria, less likely SIADH

• Low: Overhydration, diabetes insipidus, renal dysfunction

• ~1.010: Isosthenuria (loss of concentrating ability)

For healthy individuals: Primarily reflects hydration status. Persistent abnormalities may indicate renal or endocrine dysfunction.