Dear Dr. Donohue: You probably have discussed this disease before, but it didn't apply then. I have been diagnosed with myasthenia gravis. I am a 79year-old woman in good health. How serious is this? Now it affects only my vision. My doctor has prescribed Mestinon. Does myasthenia progress?
Muscles work only when nerves connect to muscles by way of a chemical messenger acetylcholine. It's released by nerves, and that chemical latches on to what's called a muscle receptor. When it does so, the muscle contracts. Myasthenia is a condition in which antibodies made by the immune system block the attachment of acetylcholine to muscle. It's the equivalent of pulling a lamp's cord from the electrical outlet.
Myasthenia strikes at all ages, but mostly between 20 and 30 for women and between 50 and 60 for men. You're at an age somewhat advanced for its onset. Early symptoms include fatigue, weakness of the arms and legs, difficulty swallowing and difficulty chewing.
When eyelid muscles are involved, the lids droop. When muscles that move the eye are stricken, a variety of visual troubles can arise. One of the most common is double vision. The two eyes are not aligned as they would be with normal eye-muscle function. Twothirds of those with ocular myasthenia go on to develop myasthenia at other muscle sites. A number of approaches restore normal vision to those with ocular myasthenia.
What will happen to you down the road is unpredictable. You are taking the medicine most often prescribed for myasthenia, Mestinon. It restores muscle function for a great many patients. If Mestinon doesn't prove helpful, other medicines are available.
Do yourself a huge favour. Contact the Myasthenia Gravis Foundation to get the latest information. It will alert you to local MG groups where you will find people who have been through the same experiences you are going through. You can reach the foundation at its website, www.myasthenia.org. There's also the MG Coalition of Canada ( www.mgccccmg.org)
Dear Dr. Donohue: My recent bloodwork showed my creatinine at 3.8 and my blood urea nitrogen at 27, both of which are out of range.
My primary-care doctor informed me that there are no tests to determine the cause of this high elevation. The research I did on the Internet implies that there is a possibility of kidney failure. I would appreciate some guidance, as I am not comfortable ignoring the situation.
Creatinine comes from muscle turnover. A fairly constant amount is produced daily. All of it is filtered into the urine by the kidneys. If blood creatinine levels rise, that strongly implies kidney trouble. The normal creatinine for a woman is 0.5 to 0.9 mg/dL (40 to 80 micromoles/L), and for a man the numbers are 0.6 to 1.2 (53-106). Your reading of 3.8 is very high and implies significant kidney trouble.
BUN, blood urea nitrogen, is the end product of protein metabolism. Like creatinine, it is a marker of kidney function. The normal BUN is 7 to 20 mg/dL. Your urea nitrogen is only slightly elevated.
I can't tell you why there's such a discrepancy. Both should rise an equivalent amount. You are correct in feeling uncomfortable about your creatinine value. You have to find whether the lab made an error or have the test repeated. If it remains high, you need to consult a nephrologist, a specialist in kidney diseases.
Dear Dr. Donohue: You published an article sometime back that mentioned a low output of thyroid hormone could raise the cholesterol reading. My question is: Does a low output of thyroid hormone also contribute to an elevation of triglycerides?
Yes, it can. It doesn't happen to everyone with a low output of thyroid hormone (hypothyroidism), but it possibly can be related to it.
Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible.