DEAR DR. DONOHUE: My husband has Paget’s disease. He is in constant pain, but nothing helps. I have never seen anything in your column about Paget’s. Would you please provide some information on it? – J.B.

ANSWER: Every day, bones undergo constant remodeling. Today’s bones are not the same as yesterday’s. Cells called osteoclasts are the bone demolition crew. They nibble at and dispose of old bone. Osteoblasts, the bone construction crew, immediately lay down new bone. As long as demolition and reconstruction are balanced, all is well.

In Paget’s disease, demolition outpaces reconstruction. In a race to keep up, the construction cells hastily lay down new bone that is structurally inferior to normal bone. That makes the new bone fragile – easily broken. Furthermore, the new bone is haphazardly constructed. It’s deformed. The expanding deformity creates painful muscles and joints. Pain is a hallmark Paget’s disease symptom. Involvement of the skull can lead to headaches and hearing loss.

The bones most often affected are pelvic bones, backbones, the skull, the femur (the thigh bone) and the tibia (one of the lower leg bones).

What causes Paget’s is still an unanswered question, even after more than 100 years since the British doctor James Paget first described it.

Pain relief is a primary goal of treatment, and it should be obtainable for most patients. Only recently have medicines that arrest the process become available. Some names are Fosamax, Actonel and Aredia. Perhaps it is just too soon for those medicines to have taken hold for your husband.

Have your husband contact the Paget Foundation at 1-800-23-PAGET. He’ll find a source of information and help that is unsurpassed among medical foundations. Its Web site is www.paget.org.

DEAR DR. DONOHUE: I am in my upper teens and am getting gray hair. A few strands appeared when I was younger. Now it is really noticeable. Is there anything I can do to keep my hair black without dyeing it? – N.N.

ANSWER: Melanin, the same pigment that imparts color to skin, gives hair its color. Related pigments also contribute to hair color. Around age 34 in whites and 10 years later in blacks, the pigments begin to disappear, and hair starts to turn gray.

When the process occurs before age 20 in whites or 30 in blacks, it’s premature graying, and most often it is an inherited trait. However, there are some illnesses that can be implicated in it.

Pernicious anemia and thyroid disorders are two examples. Malnutrition is another condition that fosters early graying. Some rare genetic illnesses can also cause it.

You have no symptoms or signs other than the gray hair, so background illnesses are unlikely in your case. If there are no treatable, associated illnesses, the only option is to resort to coloring the hair. Patchy spots of gray can be due to vitiligo.

If you part the gray hairs and expose the scalp, you’ll know vitiligo is the cause if the exposed scalp is unpigmented.

DEAR DR. DONOHUE: I am a 73-year-old male, and a CT scan has revealed a fungus in my lungs. My doctor described it as calcified granulomas and said it is common in the Midwest. Can this get progressively worse and affect my breathing? Can it be cured? – D.L.

ANSWER: My hunch is your doctor indicated histoplasmosis, a common fungal infection of the Midwest, the Southeast and mid-Atlantic states. The fungus lives in soil and in places enriched with bird droppings. Infection occurs when a person breathes in air that carries fungal spores.

Most infections are mild or completely lacking in symptoms. However, the body encases fungal spores in heaps of calcified cells called granulomas.

They can be seen in chest X-rays or scans. More likely than not, your encounter with histoplasmosis is a thing of the past that will not come back to bother you in any way.

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.