Myoglobinuria REF: Harrison's Internal Medicine 17th edition chapter 382, Physiology and pathology of the urine by john dixon p. 49 Red color urine may be due to hemoglobin or myoglobin. In the question clue is given that patient is an athlete who competed in an event which lead to sternous exercise and hence increased myoglobin in the urine. "The states of energy deficiency cause activity-related muscle breakdown accompanied by myoglobinuria, appearing as light-brown- to dark-brown-colored urine"