40 yr old female presents with urine darkening on standing, joint pain and stiffness, and pigment deposition in joints. What is the probable diagnosis?
Phenylketonuria
Tyrosinemia
Alkaptonuria
Tyrosinemia
Ans. is 'c' i.e., Alkaptonuria * Individual presenting in 4th decade with joint pain and stiffness and urine darkening on standing and pigment deposition in joints, is suggestive of alkaptonuria.Ochronosis (Alkaptonuria):* Alkaptonuria is a rare, heritable disorder characterized by the appearance of homogentisic acid in the urine , darkpigmentation of the connective tissues (ochronosis ) and calcification of hyaline and fibrocartilage.* Inborn error is an absence of homogentisic acid oxidase in the liver and kidney. Those affected usually remainasymptomatic until the 3rd & 4th decade when they present with pain and stiffness of the spine & (later) larger joints.* Dark pigmentation of ear cartilage & sclera and staining of clothes by homogentisic acid in sweat. Urine turnsdark brown when it is alkalinized or if it is left to stand for some hours.* X- ray reveal narrowing & calcification of intervertebral discs. Peripheral joints show chondrocalcinosis &severe osteoarthritis.
Metabolic Bone Disease