High CK level is result of muscle breakdown

DEAR DR. ROACH » Since September, my son has been in the hospital for a high CK level. Initially, the CK level was 4,000, and as of yesterday, it’s increased to 8,000. Since his result is so high, his doctor suggests he take a genetic test. Do you have any suggestions to reduce the CK level?

— S.L.

DEAR READER » The CK lab test measures the amount of a muscle enzyme called creatine kinase. It is sometimes called creatine phosphokinase, or CPK, but it’s the same enzyme.

Small amounts of CK are normally present in the blood, but the levels rise as a result of muscle breakdown. Levels in the multiple thousands or tens of thousands raise the concern for rhabdomyolysis, a syndrome of muscle cell death. This cell death can be caused by muscle damage from extreme trauma such as a crush injury, from overexertion in an untrained person, from damage due to toxins — including prescribed and recreational drugs, or infection or severe electrolyte disorders.

In most cases of rhabdomyolysis, recovery begins with CK levels going down in a few days. Treatment of very high CK is aimed at protecting the kidneys from the damage done by all of the muscle breakdown products in the blood. This usually means giving aggressive intravenous fluids, and occasionally means temporary dialysis.

Persistently high CK levels of that range raise the concern for neuromuscular disorders. It’s impossible to be specific about cause without knowing how old your son is, whether the initial event started with exertion and whether he has symptoms. There are numer- ous neuromuscular diseases, many of which are genetic, that can cause elevations in the CK lev- els. The fact that his doctor wants a genetic test makes me suspect they are also thinking about neuromuscular disease as a cause of the high CK level. Only when there is a specific diagnosis can a specific treatment be recommended.

Persistently high CK levels of that range raise the concern for neuromuscular disorders.