Definition of Urine

urineUrine – the liquid the kidneys generate to pass wastes and excess fluid from the body. The typical adult makes and passes between 1,500 and 3,000 milliliters (1.5 to 3 liters) of urine every 24 hours.

Numerous variables influence the volume and composition, though in general urine is 95 percent water and 5 percent suspended or dissolved solids.

Most of the solids urine contains are organic wastes in the forms of urea, uric acid, creatinine, and ammonia.

These are the nitrogen-based waste byproducts of metabolism that the kidneys filter from the blood. The urine also contains minerals (electrolytes) the kidneys excrete to maintain the body’s electrolyte and fluid balance.

Excreted electrolytes include sodium, potassium, chloride, magnesium, phosphate, and calcium. Normal urine may contain small amounts of albumin (protein).

Color of Urine

Urine of normal concentration is pale yellow and has no odor. Dilute urine is colorless; concentrated urine can appear dark yellow to orange. Dietary substances, certain medications, and certain health conditions can alter the color as well as the odor of the urine.

Normal urine is slightly acidic and has a specific gravity of 1.010 to 1.025, slightly above that of water. Deviations from normal urine composition and concentration suggest various health conditions and may require diagnostic evaluation.

For further discussion of the urinary system’s structure and function please see the overview section “The Urinary System.”

See also ALBUMINURIAANURIACYSTINURIAHEMATURIAOLIGURIAUREMIAUROLITHIASIS.

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