DEAR DR. DONOHUE: I have not had a menstrual period for four months. I am 39 years old. My doctor doesn’t seem to think there is anything to worry about. I have hot flashes occasionally. I am single, not sexually active and have never had children. Could I be going through early menopause? Should I be worried? – K.B.

ANSWER: Amenorrhea – the loss of menstrual periods – is defined as the absence of periods for six months. You are approaching that deadline, and you should be concerned. The causes for menstrual-period loss are many, and sometimes they have implications that impact health – if not immediate health, health in the near future. A loss of estrogen, for example, leads to severe osteoporosis.

You should find a doctor who will perform at least a cursory search for the common reasons for periods to stop. Pregnancy, of course, is the No. 1 cause, but this doesn’t apply to you.

Second on the list of causes is polycystic ovary disease. Large, cyst-covered ovaries, diminution of menstrual periods, growth of facial and chest hair, blood-sugar abnormalities and high levels of circulating male hormone are some of the salient features of the syndrome. Not all signs have to be present. A physical exam, along with some lab tests and perhaps an ultrasound of the ovaries, can provide the diagnosis.

Pituitary-gland tumors are another important cause. One such tumor produces too much prolactin, the hormone that stimulates milk production. Leaky breasts along with a loss of periods are important clues to this problem. Milk production, however, is not always present with this tumor. In fact, its absence is more common than its presence, so it is not a reliable sign of a prolactin-producing tumor. Blood tests can detect excessive levels of the hormone.

A thyroid gland that is producing too little or too much thyroid hormone can also upset normal menstrual cycles.

You need a doctor who will at least start the search for the cause of your problem.

DEAR DR. DONOHUE: Please say something about scleroderma. I cannot find any information on this illness. – R.H.

DEAR DR. DONOHUE: A friend recently died from scleroderma in a matter of months. I have never head of it. Can you tell me more? – C.K.

ANSWER: The translation of “scleroderma” is “hard skin,” but it’s an illness that is more than skin-deep. Collagen, the protein that serves as a supporting scaffold for skin and body organs, is produced in overabundance. The skin becomes thick, hard and so taut it can become difficult to bend the fingers or smile.

Collagen can infiltrate the esophagus and make swallowing difficult. When it deposits in the lungs, it forms strands of scar tissue that make it difficult for oxygen to pass from the lungs into the blood. That, in turn, makes people breathless. The same processes can occur in the kidneys and the heart.

What causes the rampant production of collagen is something yet to be determined.

The course scleroderma takes is unpredictable. CK’s friend had an unusually aggressive form of the illness. Although there is no medicinal cure for it, there are medicines that can control the organ damage inflicted by it. Modern blood-pressure medicines can almost always rein in the rise in blood pressure that comes about from scleroderma involvement of the kidneys, and that has prolonged the lives of many patients.

DEAR DR. DONOHUE: I had spinal surgery in the early 1980s, and it was a great success. It corrected sciatica by repairing a back disk.

Recently back pain has returned, and I have weakness in my legs that makes it difficult to walk. Stairs are difficult to navigate. I have had a CT scan and X-rays, and my doctor feels there is no need to see an orthopedic doctor. What do you think? – B.D.

ANSWER: I think there is a great need to see an orthopedic doctor, even though the X-rays and scans are not revealing. They often aren’t. Demand a referral.

DEAR DR. DONOHUE: How long does alcohol stay in your system? When is it safe to drive after drinking two or three beers? – M.L.

ANSWER: On average, it takes 60 to 90 minutes to metabolize one standard drink. A standard drink is 12 ounces of beer, 5 ounces of wine or 1.5 ounces of 80-proof whiskey.

Your second question is nearly impossible to answer. It encompasses too many factors, such as body size, the person’s tolerance for alcohol, how much and what kind of food is in the stomach, and the time span in which the beers were drunk.

It is far safer for a potential drinker (and the public) to completely abstain if he or she is going to drive.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.