“He’s had these pains all of his life.” The case of Hammid S. Hammid’s case was very straightforward. The physician in Afghanistan focused on his dark urine, thinking it was caused by bilirubinuria,...

“He’s had these pains all of his life.” The case of Hammid S.

Hammid’s case was very straightforward. The physician in Afghanistan focused on his dark urine, thinking it was caused by bilirubinuria, which in turn led to a reasonable but erroneous presumption that something was wrong with his liver. Myoglobin also produces dark urine, just as do hemoglobin and bilirubin. The best clues were in his mother’s words: the dark urine always came after cramps, and the cramps always were related to exercise and disappeared with rest. The combination pointed straight to glycogen storage disease with rhabdomyolysis and myoglobinuria. Confirmation came with the study of venous blood lactate in his forearm after forearm exercise. If he were burning glucose normally, he should have liberated lactic acid. Postexercise lactic acid was not increased, indicating impaired glucose metabolism. Muscle biopsy showed increased glycogen content of muscle fibers, finalizing the diagnosis.