Alkaptonuria Black urine disease

• Facts:
  Deficiency of homogentisic acid oxidase causes large amounts of homogentisic acid to accumulate in the body and then be excreted into the urine
• History / PE:
  Dark or black urine on standing
  Ochronosis (dark pigment in connective tissue)
  Arthritis
• Diagnosis:
  Homogentisic acid in urine (confirmatory)
• Differential Diagnosis:
  Phenylketonuria (musty odor urine, blue eyes, fair skin)