DEAR DR. DONOHUE: I am writing on behalf of my father. He is almost 92 and is mentally sharp. Five years ago, he was diagnosed with multiple myeloma. He was told he had five more years to live.

Recently he saw a substitute doctor and was told that the diagnosis had changed to monoclonal paraproteinemia. He was given no explanation or treatment. The only information I can find is intended for experts.

Will you please explain this condition? I know we’re talking about a 91-year-old man, but he still deserves a fighting chance. – L.S.

ANSWER: Multiple myeloma is cancer of a bone marrow cell, the plasma cell. The cancerous plasma cells expand in the bone marrow and lead to bone erosions and bone breaks.

They also can spread to distant sites. In addition, blood calcium invariably rises in multiple myeloma. Since plasma cells displace other bone marrow cells, the production of red blood cells falls, and anemia results. Multiple myeloma also leads to kidney failure.

A clone is a group of identical cells. “Monoclonal” means the group of cells arose from a single cell. “Paraproteinemia” encompasses many illnesses with traits similar to multiple myeloma.

Those illnesses include Waldenstrom’s anemia, amyloidosis and monoclonal gammopathy of undetermined significance – MGUS. That’s what I believe your father has.

MGUS is not an uncommon condition. It’s found in up to 2 percent of the population and in an even higher percentage of those over 70 – 7.5 percent. Early on, it looks very much like multiple myeloma.

There are strange plasma cells in the bone marrow, but fewer than the number seen in myeloma. It only rarely becomes cancer. Most patients have no symptoms. Their blood calcium is normal, unlike the high calcium in myeloma. They are not anemic – another divergence from myeloma. No treatment is needed.

It’s too bad your dad and your family were under a cloud for so long. You can come out into the sunshine.

DEAR DR. DONOHUE: I am a 60-year-old woman with osteoporosis. I take a daily calcium supplement. My question concerns the amount of vitamin D I need to take.

I know it helps with the absorption of calcium. How much is enough? My multivitamin provides 100 percent of the daily value. I get it in my yogurt, my cereal and from the sun. I walk for half an hour, two days a week, and ride my bike one day a week. I also play golf twice a month. – M.L.

DEAR DR. DONOHUE: I’m a 70-year-old man who broke his hip three months ago. The doctor did a bone study and said I have osteoporosis. He said I should be taking vitamin D and calcium. How much? – R.M.

ANSWER: Vitamin D experts are busy devising new recommendations for this vitamin. Right now, the current recommendations say that the daily dose for ages 19 to 50 should be 200 IU; for ages 51 to 70, 400 IU; for 71 and older, 600 IU. The new recommendations will up the dose for everyone.

People with osteoporosis should be taking higher doses of the vitamin – 800 to 1,000 IU a day.

You, M.L., are getting plenty of the vitamin. You don’t need any more. The upper daily limit is set at 2,000 IU, but doses far in excess of that limit can be safely taken.

R.M., your calcium intake should be 1,000 to 1,500 mg a day. Did your doctor recommend any other treatment for your osteoporosis? You might want to make an inquiry about that.

DEAR DR. DONOHUE: I have pancreatic cancer. I was prescribed Xeloda. Have you ever heard of that medicine? What do you think about it? – C.F.

ANSWER: Xeloda is an oral chemotherapy drug. Inside tumor cells, it changes into 5 FU, a drug that has a long history of treating cancer. Xeloda can be combined with one or more other chemotherapy drugs.

It’s a good drug. If it’s the one your doctor judges to be best for the kind of pancreatic cancer you have, you can trust the doctor’s choice. The choice of treatment for pancreatic cancer depends on how the cancer cells appear when examined with a microscope, the size of the cancer, the extent of its spread and the health of the person who’s under treatment.

DEAR DR. DONOHUE: I oversee the weight room at our local high school. One of the athletes asked me why his breath had what he called a metallic odor to it after his last repetition on his third set. Can you tell us why this happens? ? J.R.

ANSWER: My apologies to you and to the athlete. I haven’t a clue. I know that I will get an answer from readers and, when I do, I’ll let you know.

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.