Urine from an equine patient is red and there is positive heme reaction on urine dipstick. What would you expect if patient had myoglobinuria?

Urine from an equine patient is red and there is positive heme reaction on urine dipstick. What would you expect if patient had myoglobinuria?

• A. Decreased CK and LDH.
• B. Decreased CK and CK-MB.
• C. Increased ALT and AST.
• D. Increased creatine kinase and AST.

Answer: (D)

When muscle fibers are damaged, such as in rhabdomyolysis, enzymes stored inside muscle cells spill into the bloodstream and myoglobin is released into the urine. A red urine with a positive heme dipstick often points to myoglobinuria, not exactly to red blood cells. The most sensitive sign of skeletal muscle injury is a rise in creatine kinase, which is released from damaged muscle. AST is also present in muscle tissue and increases with muscle damage, whereas ALT is more liver-specific and may stay normal in pure muscle injury. So you’d expect elevated CK and AST in this scenario. That combination best fits muscle origin of the injury, whereas the other patterns (decreased CK, or liver-predominant enzyme changes) don’t align with skeletal muscle damage.

When muscle fibers are damaged, such as in rhabdomyolysis, enzymes stored inside muscle cells spill into the bloodstream and myoglobin is released into the urine. A red urine with a positive heme dipstick often points to myoglobinuria, not exactly to red blood cells. The most sensitive sign of skeletal muscle injury is a rise in creatine kinase, which is released from damaged muscle. AST is also present in muscle tissue and increases with muscle damage, whereas ALT is more liver-specific and may stay normal in pure muscle injury. So you’d expect elevated CK and AST in this scenario. That combination best fits muscle origin of the injury, whereas the other patterns (decreased CK, or liver-predominant enzyme changes) don’t align with skeletal muscle damage.