DEAR DR. DONOHUE: My granddaughter is very thin. She weighs 100 pounds and is 54 inches tall. She has no eating disorder. She eats everything. When she was 15½, she had her first period. Two months later, she had her second one. But now she hasn’t had one for 10 months. She will be 17 shortly. I told my daughter to take her to the doctor for a shot or pills. The doctor said to wait for a year and then bring her in. He doesn’t think there is a problem. He says she’s thin, and that’s why she doesn’t have regular periods. Please advise. – N.B.

About 95 percent of girls have their first menstrual period between the ages of 12 and 14.5. Not having a period by age 15, 16 at the latest, is considered abnormal. In the first two years of menstruation, a young girl doesn’t release an egg with every period, and her cycles aren’t as regular as they eventually will be. Your granddaughter’s story might not be as abnormal as it sounds.

A girl must have a minimum amount of body fat to have normal periods. Seventeen percent of her weight has to be fat to initiate periods, and 22 percent of her weight has to be fat to maintain normal periods. Your granddaughter’s body mass index, BMI, an indication of body fat, puts her as being normal. Did you make a mistake about her height? Did you mean she was 64 inches (5 feet 4 inches) and not 54 inches? If she is 64 inches tall, she is underweight, and perhaps correcting that would promote normal periods. Even though she’s a good eater, she needs to put on more pounds by adding calorie-dense foods to her daily diet. One or two milkshakes a day could increase her weight to the level that supports menstrual periods.

Your granddaughter should first work on the weight issue. If correcting that doesn’t initiate more-frequent periods, it would be appropriate for a doctor to search for the many other causes of this condition, including having too little estrogen. One indication that estrogen production isn’t up to par is no evidence of breast development and no pubic hair. Proper advice cannot be given until the cause of her period cessation is discovered.

DEAR DR. DONOHUE: Is it better to take fluids before or after meals but not during meals? What is the importance of vitamin B-12? Should the vitamin be given in shots? Does everyone live with the aches and pain that I do? What can you take for dry skin? – R.M.

I drink fluids before, during and after meals. If that’s wrong, my body has learned to live with it. Vitamin B-12 takes part in the production of red blood cells, and it protects the integrity of nerves. A person can take it orally. Only those with pernicious anemia need B-12 shots. I don’t know how many and how great are your aches and pains, but medicine should be able to control most pain. Moisturizers hydrate dry skin. After a shower or bath, leave a little dampness on your skin by patting it with a towel. Then apply a moisturizer. Petroleum jelly works well and is cheap.

DEAR DR. DONOHUE: My husband has had four bypasses inserted in heart surgery, a hip replacement and two cataract surgeries, all in the past five years. He goes to Colorado to hunt elk and has done so for years. Last year, he has been getting short of breath when he does any work, but he doesn’t let it stop him. He still hunts with his three sons, his son-in-law and their friends. They take him up in the mountains. He has trouble breathing. The trip home took 36 straight hours with a heavy cigarette smoker in the car. He ended up in the hospital for two days. The other day, they took three tubes of blood from him, and he passed out. He never could give blood. Could this be due to his blood thinner? He is 82. – D.P.

Your husband is one gutsy guy. I admire him.

The blood-thinning medicine didn’t make him pass out. It’s more likely to have been a psychological thing. His hunting at high elevations and his marathon car trip should be better planned. How high is this spot? Medicines can help him to adapt to it. His breathlessness could be a sign of heart failure from overdoing it. The cigarette smoker ought to smoke only when the car stops, when he gets out. Your husband has to discuss these matters with his doctor.

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

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