Not Medical Advice: Normal urine is straw yellow to amber in color. Abnormal colors include bright yellow, brown, black (gray), red, and green.
Black-gray urine may result from melanin (melanoma) or homogentisic acid (alkaptonuria, a result of a metabolic disorder).
Alkaptonuria is an inherited condition that causes urine to turn black when exposed to air. Ochronosis, a buildup of dark pigment in connective tissues such as cartilage and skin, is also characteristic of the disorder. People with alkaptonuria typically develop arthritis, particularly in the spine and large joints, beginning in early adulthood.
Most people take bladder control for granted. But for about a third of people ages 30 to 70, incontinence is a big issue. Check out some tips on how to keep your bladder healthy and minimize trouble if you do have incontinence at Health.com.