Specific Gravity

Definition

Urine specific gravity is a measure of urine concentration, the density of urine compared to pure water. It reflects the kidneys' ability to concentrate or dilute urine.

Normal Range

1.005 to 1.030

Implications

• High (greater than 1.030): Dehydration, glucosuria, proteinuria, SIADH.
• Low (less than 1.005): Diabetes insipidus, overhydration, diuretic use.
• Fixed (around 1.010): Loss of concentrating ability. Chronic renal failure.

Nursing Considerations

Check specific gravity as part of urinalysis. Correlate with clinical findings. Monitor in DI (low) and dehydration (high). Patients on tube feedings or IV fluids require monitoring to maintain adequate hydration.

NCLEX Relevance

High SG = dehydration. Low SG = DI or overhydration.