DEAR DR. DONOHUE: What raises blood calcium? I have had a high reading for three years. The doctor mentions it every year, but never says what she or I can do about it. How do I lower it? Will staying away from calcium-rich foods bring it down? What kind of symptoms does it cause? I don’t have any. – C.S.

ANSWER: How high is your calcium? Normal values are 9 to 10.5 mg/dL (2.2 to 2.6 mmol/L). Symptoms don’t appear until the level rises to 11.5 (2.9). Some typical symptoms are fatigue, mental confusion, loss of appetite, constipation, abnormal heartbeats, kidney stones, ulcers and loss of bone calcium. Lower values (high but not terribly high) don’t cause any symptoms. Avoiding calcium-containing foods won’t bring the reading down.

A frequent cause of high blood calcium is an overproduction of parathyroid hormone. Four small glands, located behind the thyroid gland in the lower neck, make that hormone. It draws calcium from bone and increases calcium absorption from the digestive tract. Normally, the glands shut down when blood calcium levels are normal. Not so in hyperparathyroidism, the condition where the glands have run wild.

Hyperparathyroidism doesn’t always require immediate treatment. Around 80 percent of people who have the problem have no symptoms. If a person is older than 50 and has an elevated blood calcium but has no symptoms, the doctor can watch that person without prescribing any treatment. The doctor must be sure that the patient’s bones are not losing too much calcium and that the kidneys are functioning well in spite of the higher-than-normal blood calcium. I would guess that you fall into this category of people with high blood calcium.

Overworking parathyroid glands are not the only cause of high calcium readings. Too much vitamin D and vitamin A, Paget’s bone disease, some cancers, thiazide water pills and lithium can all raise blood calcium. Doctors must be sure that elevations are not due to these causes.

DEAR DR. DONOHUE: Twice my husband’s stool tested positive for blood. We are both quite upset over this. We fear cancer. He has to have a colonoscopy. What are his chances of not having colon cancer when his stool test is positive for blood? – P.K.

ANSWER: His chances of not having cancer are good, but his test results require his doctor to pursue the cancer question until the matter is settled. Colonoscopy will settle it.

The stool blood test is not a terribly reliable cancer test. It can be falsely positive and falsely negative. Colon cancers are not the only things that bleed. Stomach irritation often leaks blood into the digestive tract, and that turns the test positive. A little blood loss from hemorrhoids can do the same thing.

Did your husband take aspirin or an anti-inflammatory drug like Advil or Aleve in the days before his stool tests? They’re another cause of gastrointestinal bleeding.

How about his diet? Many stool blood tests require that the patient eat no red meat, poultry, fish, some raw fruits and some raw vegetables before the test is performed.

Your husband having to have a colonoscopy is a blessing in disguise. Everyone should have this procedure when they turn 50. It’s one of the best colon cancer detection tests there is.

DEAR DR. DONOHUE: When I was 32, right after delivering my fourth child, I had my tubes tied. Guess what? I am now 42 and pregnant. How could this happen? – R.W.

ANSWER: It happens, albeit infrequently. You would think that tying the tubes that bring eggs to the uterus would be a 100 percent reliable way not to have any more children. It’s close to being 100 percent reliable, but it doesn’t quite earn foolproof status. If 1,000 women who have had their tubes tied are followed for 10 years, 18 will have become pregnant in that time.

The method of tying the tubes figures into failure of the procedure. Even if the tubes are cut and their ends are tied, the severed ends can rejoin and a new channel can form that allows passage of eggs into the uterus.

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