: No treatment modality has been unequivocally established to reduce the complications of alkaptonuria. Commonly optional treatments include dietary limit of phenylalanine and tyrosine and large doses of ascorbic acid (vitamin C). Dietary restriction may be effectual in children, but benefits in adults have not been demonstrated.
: Alkaptonuria is a rare inherited genetic disorder of phenylalanine and tyrosine metabolism. This is an autosomal recessive form that is due to a defect in the enzyme homogentisate 1,2-dioxygenase , which participates in the degradation of tyrosine. As a result, a toxic tyrosine byproduct called homogentisic acid accumulates in the blood and is excreted in urine in large quantity. Excessive homogentisic acid causes injure to cartilage and heart valves as well as precipitating as kidney stones. Treatment with nitisinone, which suppresses homogentisic acid production, is being studied.