Urine specific gravity

Urine Specific Gravity

Urine specific gravity is a measure of the concentration of solutes in the urine. It is a common laboratory test used to assess the kidney's ability to concentrate or dilute urine. The specific gravity of urine is a reflection of the kidney's ability to concentrate urine and is an important indicator of renal function.

Measurement

Urine specific gravity is typically measured using a refractometer or a dipstick test. A refractometer measures the refractive index of the urine, which changes with the concentration of solutes. Dipstick tests use a colorimetric method to estimate specific gravity based on the color change of a reagent strip when dipped in urine.

Normal Range

The normal range for urine specific gravity is typically between 1.005 and 1.030. Values within this range indicate normal kidney function, while values outside this range may suggest a variety of conditions.

Clinical Significance

Low Specific Gravity

A low urine specific gravity (below 1.005) may indicate conditions such as diabetes insipidus, excessive fluid intake, or renal tubular damage. It suggests that the kidneys are not concentrating urine effectively.

High Specific Gravity

A high urine specific gravity (above 1.030) can be indicative of dehydration, diarrhea, emesis, or heart failure. It suggests that the kidneys are concentrating urine more than usual, often due to a lack of fluid intake or increased fluid loss.

Factors Affecting Urine Specific Gravity

Several factors can affect urine specific gravity, including fluid intake, renal function, and the presence of substances such as glucose or protein in the urine. Certain medications and medical conditions can also influence specific gravity readings.

Related Tests

Urine specific gravity is often measured alongside other tests such as urine osmolality, urine pH, and urinalysis to provide a comprehensive assessment of renal function and overall health.

Related Pages

• Urinalysis
• Kidney function
• Diabetes insipidus
• Dehydration

A refractometer used to measure urine specific gravity.