Urine that leaves the body looking normal and turns black after standing in the air is one of medicine's most distinctive warning signs. It points to alkaptonuria, a rare inherited disorder that also stains cartilage and other tissues and slowly stiffens the spine and joints.
The condition is the subject of a new image report, titled simply "Alkaptonuria," published in the Oct. 14, 2026, issue of The New England Journal of Medicine by physicians Prasanta Padhan and Pratima K. Singh of the Kalinga Institute of Medical Sciences in Bhubaneswar, India. It comes a little more than a year after U.S. regulators approved the first treatment for the disease in this country.
