QUESTION: I'm too shy a person to ever suggest this to my doctor, but I feel I am being misdiagnosed. I am almost certain that the high blood pressure I have is not really high blood pressure but a temporary thing. I have the feeling that the readings taken in the doctor's office come from nervousness. I have followed orders about diet and salt, but still I am told my pressure is up. Now I have expensive prescriptions, which I don't want to start. I don't want to question my doctor either. So what do I do? - W.V.

ANSWER: By all means, tell your physician exactly what you tell me. You could be right, and it can be settled. Many patients get so uptight in an examining room that several tests results are thrown off. An example is the blood pressure reading. The name for it is white-coat hypertension.Blood pressure is never static. It varies by the time of day, by activity, and by emotional states. It even drops 15 points during sleep. Some individuals have reported as much as a 30-point rise in doctor's office settings.

Taking pressure readings at home at various times can settle the matter. In fact, new experimental devices permit continuous pressure readings, much as Holter monitors permit heart rhythm recordings. An arm cuff inflates automatically at predetermined times over a 24-hour period. This can provide from 50 to 100 distinct readings to get a very accurate measure of true blood pressure.

Note: Such devices are in experimental development stages and not widely available yet. The fact that the need for such devices is seen indicates just how common your problem is.

QUESTION: I am a healthy male in my mid-20s. In my work I have to present myself to large audiences. My problem is that I get terribly nervous at such times. I went to a cardiologist. After hooking me up to a heart machine, he concluded that I have a healthy heart. He then prescribed low-dose beta blockers (Inderal) pills. I am to take a pill before a presentation. My other doctor tells me the cardiologist is wrong in prescribing the beta blockers for this purpose. He prescribed Valium, a tranquilizer. Could you address this subject? Could either pill affect my sex desire? - N.W.

ANSWER: First of all, it would be really stretching things to suggest that any problem might arise from a tablet a week of either Inderal or Valium. My personal choice would be the Inderal, however.

Unlike tranquilizers, beta blockers are not likely to make you groggy or pose any temptation to addiction. They merely block excessive nerve discharge. I have prescribed beta blockers for just such limited-use situations. Many performers, for example, rely on beta blockers to allay performance anxiety.

Ideally, any such use of drugs, no matter what kind, should be done in tandem with earnest efforts to come to terms with the real problem, the anxiety cause.

QUESTION: Tell me about motor neurons and Gehrig disease. - L.K.

ANSWER: Motor neurons are nerve cells in the spinal cord that transmit messages to get arms and legs to move. Lou Gehrig disease is a motor neuron problem. The nerve cells are being destroyed, causing muscle weakness to the point of paralysis. An example is amyotrophic lateral sclerosis (Gehrig disease). Often the causes of motor neuron disorder is unknown.

To find out what causes high blood pressure and what can be done to treat it, send for a copy of Dr. Donohue's booklet No. 4, "Blood Pressure and Your Health." Send your request to Dr. Donohue/No. 4, P.O. Box 830, Gibbstown, NJ 08027-9909. Enclose a long, self-addressed, double-stamped envelope and $2.

Dr. Donohue welcomes reader mail but regrets that, due to the tremendous volume received daily, he is unable to answer individual letters. Readers' questions are incorporated in his column whenever possible.