Review Question - QID 108980

This patient is presenting with dark urine, cocaine use, and a history of intense exercise suggesting a diagnosis of rhabdomyolysis. The best initial step in management is IV fluids.

Rhabdomyolysis classically presents with dark urine that occurs after intense exercise (running a marathon) or cocaine use. The classic finding of a positive urine dipstick for red blood cells followed by zero red blood cells found on microscopy further supports the diagnosis. The reason for this finding is that myoglobin (from the damaged muscle cells) cross reacts with the urine dipstick making it positive. Other important laboratory findings are hypocalcemia (from SERCA sequestering calcium from damaged muscle cells), as well as high potassium and creatine kinase (leaked from damaged muscle cells). Due to the damaging and toxic effects of myoglobin on the kidneys, the next best step in management is aggressive IV hydration.

Figure A demonstrates an EKG with a normal rate and rhythm, and no signs of a STEMI.

Incorrect Answers:
Answer 1: Renal ultrasound is the diagnostic test of choice in pregnancy to diagnose kidney stones since it does not expose the patient to radiation. Kidney stones present with flank pain that radiates to the groin and hematuria.

Answer 2: CT scan is another appropriate diagnostic test (in non-pregnant patients) for diagnosing kidney stones which present with flank pain that radiates to the groin and hematuria.

Answer 4: Observation and waiting for the patient to metabolize illicit substances himself would be appropriate if the patient was simply detoxifying from cocaine and amphetamine use. The damage that could occur to this patient's kidneys from myoglobin requires aggressive hydration.

Answer 5: Phlebotomy and choloroquine are two treatments indicated for porphyria cutanea tarda (PCT). PCT can present with dark urine, photosensitivity, hyperpigmentation, and hypertrichosis.

Bullet Summary:
Rhabdomyolysis typically occurs in patients who use cocaine or participate in strenuous exercise and presents with dark urine; the best initial step in management is IV fluids.