This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in


Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Alkaptonuria is caused by deficiency of homogentisic acid oxidase which converts homogentisic acid to acetoacetic acid.

Homogentisic acid which accumulates in the urine oxidises on standing, turning the urine black.

The tissues may become darkened, described as ochronosis, and there may be associated degenerative changes.

This condition, in contrast to phenylketonuria, has no effect on intelligence. However, cartilage deposition may result in degenerative arthritis.

Related pages

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page