Q: I am a 69-year-old man. For my past three physical exams, my blood work has been excellent, except for the creatine phosphokinase; it has been rising steadily. It is now above 700. My activities include handball, weightlifting, biking and deep-tissue massages every week.
My doctor wants me to have my blood retested in a month, after stopping all strenuous activities. He also wants me to stop the massages until then. I do have a lot of muscle and joint pain. He seems to think I might be overworking my muscles. If he sees no drop in the CPK after a month, he will send me to a specialist. What do you think? I take a low-dose statin.
A: Creatine phosphokinase is an enzyme in the muscle, normally present in the blood in small amounts. Large amounts of CPK indicate ongoing breakdown of muscle. There are many possible causes. Extensive muscle activity is enough to cause it, which is why your doctor wants to recheck the level after you stop exercising for a while.
Certain muscle conditions can cause low levels, while serious muscle conditions, such as polymyositis, cause a high level. A specialist, usually a neurologist, can help diagnose the conditions with a muscle biopsy.
Statins make muscle breakdown worse after exercise, even at a low dose. Pravastatin and fluvastatin are least likely to cause the side effect. You should speak to your doctor about whether the medication is really necessary. It might be worthwhile to see what happens to your CPK level off the statin.
Q: Orange juice was a staple for breakfast when we were growing up. Mom would say, “Hurry up and drink your orange juice before it loses its vitamins.” I’ve noticed that, when a carton of juice is left out for even five minutes, it swells. Was she right?
A: Mom was partially right. Orange juice will lose its vitamins over time, especially if it gets warm. But that doesn’t happen in five minutes. Products that rest on the shelf for a long time lose their vitamins. As a student in organic chemistry, I did an experiment to find out how much vitamin C is in certain products. Fresh fruits and vegetables (especially red bell peppers) have a great deal. A canned juice, purportedly high in C, had none at all.
Orange-juice containers will swell if bacteria in the juice release gas, at which point the juice should be discarded. I wonder, however, whether the swelling in five minutes has to do with the air in the carton expanding because of the relative warmth of the air compared with the refrigerator.
Dr. Roach answers letters only in his North America Syndicate column but provides an order form of available health newsletters. Write him at P.O. Box 536475, Orlando, FL 32853-6475; or ToYourGoodHealth @med.cornell.edu.