Alcaptonuria. Homogentisic acid oxydase deficiency.
Incidence
Autosomal recessive condition. There are no neurological abnormalities or symptoms.
Clinical Characteristics
Patients with alcaptonuria develop generalized pigmentation of connective tissue, so called ochronosis, and arthritis beyond their second or third decade. Children are suspected of suffering from this disorder when the urine darkens at high pH. The disorder is caused by a deficiency of homogentisic acid oxydase in liver and kidney, resulting in a high excretion of homogentisic acid in the urine. Treatment consists of protein restriction. The main symptoms in children is urine darkening. Cornea pigmentation can be present in adolescence and usually present in adulthood. All parameters of routine laboratory are normal. The urine homogentisic acid is elevated at all ages. There is no neurological abnormalities or symptoms.
Precipitants
Probable high protein intake produce or trigger the darkening of urine.
Provocation Tests
Making the urine alkaline will change the urine color to dark.
Diagnostic Procedures
All parameters of routine laboratory are normal. The urine homogentisic acid is elevated at all ages.