[Alkaptonuria: a rare cause of urine discoloration. Report of a case in a newborn].

UNLABELLED: Alcaptonuria is a rare hereditary disease, characterized by an abnormal blackish coloration of the urine and dark pigmentation of the conjunctive tissue which is due to a deficiency in homogentisate 1,2-dioxygenase (HGO), a phenylalanine catabolizing enzyme. An accumulation of homogentisate (HGA) is then formed, and is responsible for the dark coloration which only occurs after the urine has been exposed to air over a period of time. Signs of this disorder therefore frequently remain unnoticed during childhood, because the urine requires a relatively long exposure to air before it changes color. Diagnosis is generally made at a later date, during adulthood, following complications such as ochronosis, inflammatory arthritis, or urinary calculi.

CASE REPORT: In this study, the case has been described of alcaptonuria diagnosed in a five-month old infant. No efficient cure has yet been found, although certain treatments, including high doses of vitamin C, do seem to have a beneficial effect on limiting the complications associated with this disorder. Early diagnosis whenever possible is therefore important.

CONCLUSION: This case report is interesting because of the early diagnosis involved. In the event of any abnormal coloration of the urine, diagnosis may be established via the addition of an alkylating agent, and the levels of HGA determined by chromatography.