DEAR DR. DONOHUE: Numerous over-the-counter supplements such as DHEA and herbs claim to stimulate testosterone production. As I am one of many 70-plus-year-olds who lift weights to increase strength and muscle mass before we become too old, do you recommend such supplements? If so, which ones? — Anon.

ANSWER: Dehydroepiandrosterone, from this point on called DHEA, is a hormone made by the adrenal glands. It has weak male hormone properties. Some of it is converted into testosterone, the major male hormone.

An aside is necessary here. Many athletes and bodybuilders resort to taking male hormones to increase their strength and muscle size. These drugs are called steroids, an unfortunate choice of a word. “Steroids” include all kinds of hormones — cortisone, prednisone, estrogen and male hormones. For clarity, male hormones should be called either that or anabolic hormones, hormones that build body tissues, especially muscles. DHEA is a weak anabolic hormone.

Let me cite for you a study from the New England Journal of Medicine, a respected medical publication. The authors of this article gave 40 well-trained athletes DHEA for more than one year. After one full year, they found an increase in these athletes’ muscle size or strength.

A study of DHEA in older men demonstrated a slight improvement in the ratio of muscle to body fat. Users had a bit more muscle tissue at the end of the study than they had at the beginning, but not a whole lot.

The safety of long-term DHEA use is lacking. Male hormones promote prostate-gland enlargement, and they can foster the growth of any prostate cancer cells that might be in the gland.

I would steer clear of all male hormone products for muscle growth.

None of this applies to men who are deficient in male hormones. They can take hormone-replacement therapy safely under the direction of their doctors.

As for herbal stimulation of male hormone production, I can’t find credible evidence that it works.

DEAR DR. DONOHUE: I have a fairly large Baker’s cyst at the back of my knee. I first noticed it three years ago. I am an active senior tennis player. The past couple of years it has grown and makes my knee feel tight, but I have no pain. Two different doctors have told me not to worry because if they drain the cyst it likely will recur. What should I do? — H.S.

ANSWER: A Baker’s cyst is a behind-the-knee bulge. Actually, it’s a swollen bursa. Bursas are small disks found between tendons and bones that decrease friction as tendons rub over the bone.

The fluid in a Baker’s cyst comes from the joint. It’s the fluid that irrigates the joint. Usually, an overproduction of joint fluid indicates joint trouble, like arthritis. A one-way street runs between the knee and the Baker’s bursa. Fluid can drain into the bursa, but not out of it. That’s why it grows.

In your position, you can choose to do whatever you wish. Ignoring the bulge is a rational choice. It could rupture, and that’s painful, but that’s the extent of not having it treated now.

Cysts do recur after drainage. Instilling cortisone into them sometimes prevents that from happening.

You should, however, see if there is a problem with your knee that needs attention.

DEAR DR. DONOHUE: Our son is middle-age, and his Achilles’ tendon was injured while playing basketball. Is surgery the only remedy? — L.P.

ANSWER: If his tendon is inflamed, rest, anti-inflammatory medicines and warm soaks are all that’s needed. If the tendon tore, and the tear is large, surgery is the usual treatment. Small tears don’t always require surgery.

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.