Alkaptonuria is a rare genetic disorder in which the body is unable to properly process the amino acid tyrosine. As a result, a substance called homogentisic acid (HGA) builds up in the body and is excreted in the urine. This causes the urine to take on a dark or blackish color. In some cases, the urine may even appear to be nearly black. This discoloration, known as ochronosis, is the most common and obvious symptom of alkaptonuria.
In addition to the discoloration, the urine of people with alkaptonuria can also have a strong, unpleasant odor. This odor is a result of the HGA breaking down and producing odorous compounds. It is important to note that while the discoloration and odor are the most common symptoms of alkaptonuria, they are not the only ones. Other symptoms can include joint pain, arthritis, and heart problems.
In conclusion, the color of urine in alkaptonuria is usually dark or blackish. This discoloration is due to the build-up of homogentisic acid in the body and its subsequent excretion in the urine. Additionally, the urine may also have a strong, unpleasant odor. It is important to note that these are not the only symptoms of alkaptonuria and that other symptoms may be present as well.