Urine with phenylketonuria typically has a dark color, ranging from amber to brown. It may also have a strong ammonia odor. The color change is caused by the buildup of phenylalanine, an amino acid, in the body. When levels of phenylalanine become too high, the body is unable to break it down, resulting in excess amounts of the chemical in the urine. The chemical reaction between the phenylalanine and other substances in the urine is what causes the color change.
In a person with phenylketonuria, the color of the urine may vary from person to person. It may be a light amber color or a dark brown. The intensity of the color can also fluctuate, appearing darker or lighter depending on the amount of phenylalanine in the body.
If the color of your urine changes, it is important to see your doctor for a diagnosis. Urine color changes can indicate a number of medical conditions, including phenylketonuria. Early diagnosis and treatment can help reduce the risk of long-term complications.