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ALL / Clinical Sciences
Alkaptonuria
Alkaptonuria
Alkaptonuria (ochronosis) is a rare autosomal recessive disorder of phenylalanine and tyrosine metabolism caused by a lack of the enzyme homogentisic dioxygenase (HGD) which results in a build-up of toxic homogentisic acid. The kidneys filter the homogentisic acid (hence black urine) but eventually it accumulates in cartilage and other tissues.Alkaptonuria is generally a benign and often asymptomatic condition. Possible features include:
- pigmented sclera
- urine turns black if left exposed to the air
- intervertebral disc calcification may result in back pain
- renal stones
Treatment
- high-dose vitamin C
- dietary restriction of phenylalanine and tyrosine
Multi-level intervertebral disc calcification with disc space narrowing
+PassMedicine Notes
Alkaptonuria (ochronosis) is a rare autosomal recessive disorder of phenylalanine and tyrosine metabolism caused by a lack of the enzyme homogentisic dioxygenase (HGD) which results in a build-up of toxic homogentisic acid. The kidneys filter the homogentisic acid (hence black urine) but eventually it accumulates in cartilage and other tissues.
Alkaptonuria is generally a benign and often asymptomatic condition. Possible features include:- pigmented sclera
- urine turns black if left exposed to the air
- intervertebral disc calcification may result in back pain
- renal stones
- high-dose vitamin C
- dietary restriction of phenylalanine and tyrosine
