Specific Gravity — Normal Range & Interpretation
Urine specific gravity measures the concentration of solutes in urine and reflects the kidney's ability to concentrate or dilute filtrate. It serves as a rapid bedside indicator of hydration status, renal tubular function, and antidiuretic hormone activity. The normal range of 1.005 to 1.030 spans the kidney's full concentrating capacity in healthy adults.
| Male | Female | Unit | Category |
|---|---|---|---|
| 1.005–1.030 | 1.005–1.030 | — | Urinalysis |
Clinical Context
Urine specific gravity measures the concentration of solutes in urine and reflects the kidney's ability to concentrate or dilute filtrate. It serves as a rapid bedside indicator of hydration status, renal tubular function, and antidiuretic hormone activity. The normal range of 1.005 to 1.030 spans the kidney's full concentrating capacity in healthy adults.
Elevated specific gravity points to dehydration, hypovolemia, SIADH, glycosuria, proteinuria, and intravenous contrast exposure. Decreased values signal overhydration, diabetes insipidus, diuretic use, and advanced chronic kidney disease with loss of concentrating ability. A fixed specific gravity near 1.010, termed isosthenuria, reflects urine iso-osmolar to plasma and indicates significant tubular dysfunction.
What the AANP exam actually tests on urine specific gravity: recognizing patterns paired with clinical vignettes. Expect questions distinguishing SIADH (concentrated urine, dilute serum) from diabetes insipidus (dilute urine, concentrated serum). The exam also tests interpretation alongside serum osmolality, sodium, and urine output to identify volume status. Candidates should recognize that glucose, protein, and radiographic contrast falsely elevate readings, while early morning samples yield the most concentrated specimen. Link low specific gravity with polyuria and high specific gravity with oliguria when building differentials for fluid and electrolyte disorders commonly featured on certification questions.
Related Labs
Sources
Ready to practice?
Practice 1,500+ AANP-style questions with full clinical rationales — start a free trial.