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To Your Good Health: Elevated CPK Can Come From Overworking Muscle

Dear Dr. Roach: I am a 69-year-old male. For my past three physical exams, my bloodwork has been excellent, except for the CPK; it has been rising steadily. It is now over 700. My activities include handball, weights, biking and “deep tissue” massages every week. My doctor wants me to have my blood retested in a month, after stopping all my strenuous activities. He also wants me to stop the deep tissue massages until then. I do have a lot of muscle and joint pain. He seems to think I may 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 may be causing this CPK elevation? I do take a low-dose statin. — B.Z.

Answer: CPK (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 certainly 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 these conditions. This may require a muscle biopsy.

Statins make muscle breakdown worse after exercise, even at a low dose. Pravastatin and fluvastatin are least likely to cause this side effect. You should speak to your doctor about whether this medication is really necessary for you. It may be worthwhile to see what happens to your CPK level off the statin.

Dear Dr. Roach: Doc, orange juice was a staple for breakfast when we were growing up. If we weren’t getting to it, Mom would say, “Hurry up and drink your orange juice before it loses its vitamins.” I’ve noticed that when a carton of OJ is left out for even five minutes, it swells up, apparently due to some pretty volatile organic compounds. I’ve learned through the years that Mom was usually right. Was she right again? — M.E.K.

Answer: 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 sit on the shelf for a long time lose their vitamins. As a student in organic chemistry, I did an experiment to find how much vitamin C was in certain products. Fresh fruits and vegetables (especially red bell peppers) had a great deal. A canned juice, purportedly high in C, had none at all. Even vitamin C tablets still before their expiration date had lost 20 percent of their stated value.

Orange juice containers will swell if bacteria in the juice release gas, at which point it should (obviously) be discarded. However, I wonder if the swelling in five minutes has to do with the air in the carton expanding due to the relative warmth of the air compared with the refrigerator.

Dear Dr. Roach: Are vitamin B-12 injections effective in treating neuropathy? — G.R.

Answer: A neuropathy is any of many different conditions that affect the functioning of nerve cells. Although B-12 deficiency is one common cause of neuropathy, giving B-12 treats only the neuropathy from that specific cause. Some people have tried B-12 and other B vitamins for different neuropathies. It can’t hurt, but it may not help. A blood test for B-12 usually is definitive.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Health newsletters may be ordered from www.rbmamall.com.