If a patient presents with cherry colored urine, what test should be ordered?

If a patient presents with cherry colored urine, what test should be ordered?

• A. Check for rhabdomyolysis with CPK
• B. Urinalysis for infection only
• C. KUB X-ray
• D. Serum bilirubin

Answer: (A)

Cherry-colored urine suggests pigmenturia from muscle breakdown, i.e., myoglobin released into the urine during rhabdomyolysis. The most informative initial test is measuring creatine phosphokinase (CPK). CPK rises rapidly with muscle injury and its level correlates with the extent of damage and the risk of myoglobin-induced acute kidney injury. A high CPK supports the diagnosis and prompts urgent management with aggressive IV fluids and careful electrolyte and renal monitoring. Other tests listed don’t directly address the suspected issue. Urinalysis aimed at infection doesn’t explain the pigment in the urine. A KUB X-ray isn’t useful for diagnosing rhabdomyolysis. Serum bilirubin would point to liver or hemolysis issues rather than pigmenturia from muscle breakdown.

Cherry-colored urine suggests pigmenturia from muscle breakdown, i.e., myoglobin released into the urine during rhabdomyolysis. The most informative initial test is measuring creatine phosphokinase (CPK). CPK rises rapidly with muscle injury and its level correlates with the extent of damage and the risk of myoglobin-induced acute kidney injury. A high CPK supports the diagnosis and prompts urgent management with aggressive IV fluids and careful electrolyte and renal monitoring.

Other tests listed don’t directly address the suspected issue. Urinalysis aimed at infection doesn’t explain the pigment in the urine. A KUB X-ray isn’t useful for diagnosing rhabdomyolysis. Serum bilirubin would point to liver or hemolysis issues rather than pigmenturia from muscle breakdown.