Blood in urine and muscle breakdown: what to know

When muscle cells are damaged, they release myoglobin, a pigment that can turn urine tea-coloured, brown or red. A urine strip may detect blood even when a microscope finds few red blood cells. This differs from haematuria, where blood actually comes from the kidneys, bladder or another part of the urinary system. Heavy exercise, a crush injury, heat exposure, seizures, infection or some medicines can contribute to muscle breakdown. Kidney problems may develop because myoglobin places stress on the kidney filters, especially when dehydration is present.

Stop strenuous activity and seek same-day medical advice if the colour change follows severe exercise, an injury, prolonged immobility or marked muscle soreness. A clinician may check urine, blood tests for muscle injury and kidney function, while reviewing medicines and recent events. Do not restart intense exercise until you have been assessed. Drink normally unless a clinician has told you to limit fluids; forced drinking is not a substitute for care. If testing instead confirms urinary bleeding, possible explanations include a urinary tract infection, kidney stones or kidney infection.

Go to an emergency department for very little urine, worsening weakness, confusion, fainting, severe swelling or pain, repeated vomiting, fever with severe illness, or urine that stays dark after rest. Seek urgent help after a major injury or if you cannot keep fluids down. Visible blood or clots also needs prompt assessment, even if muscle symptoms are absent, because the source may be elsewhere in the urinary tract.

Could this colour be myoglobin or true blood? Which tests will check muscle injury and kidney function? Should any medicine or supplement be paused? How much activity and fluid are suitable while I recover? What symptoms should prompt emergency care?