India, April 3 -- Alkaptonuria is a rare genetic disorder caused by a deficiency of the enzyme homogentisate 1,2-dioxygenase. In an interview with HT Lifestyle, Dr Abhishek Agrawal, Consultant urologist, Jupiter Hospital Thane explained why t turns urine black, "This enzyme is essential for breaking down homogentisic acid, a byproduct of amino acid metabolism. When the enzyme is deficient, homogentisic acid accumulates in the body and is excreted in the urine. Upon exposure to air, this acid oxidizes, causing the urine to turn dark brown or black-a hallmark symptom of alkaptonuria." Also read | World Kidney Day 2025: What your urine can reveal about your kidney health? Doctor explains

"The black discoloration of urine is often the earlie...