Which parameter is used to assess kidney concentrating ability and is often measured in urine analysis?

• A. pH
• B. Protein
• C. Glucose
• D. Specific gravity

Answer: (D)

Urine specific gravity reflects how concentrated or dilute the urine is, which directly shows the kidney’s ability to reabsorb water under the influence of antidiuretic hormone. When the body needs to conserve water, the kidneys produce more concentrated urine, raising the specific gravity; if the concentrating ability is impaired, the urine remains relatively dilute and the specific gravity stays low even when dehydration is present. Because this measure is quick and routinely available during urinalysis, it’s the standard way to assess renal concentrating function and hydration status.

Other common urinalysis parameters point to different issues: pH indicates acidity or alkalinity, which isn’t a direct measure of concentration; protein in the urine suggests glomerular or tubular damage; glucose in urine can indicate hyperglycemia or proximal tubule problems.