DEAR DR. DONOHUE: I am 36 and have an extremely embarrassing problem that I’ve spoken to my gynecologist and family doctor about. I have to urinate every half-hour, and it’s not just a tinkle. It has happened every day for years and is worse during the night. Family and friends constantly ask, “What’s wrong with you?” Both my doctors prescribed Detrol. It didn’t help. I heard that diabetes might be the cause, so I was checked for that. I don’t have it. What could it be? – S.

ANSWER: The possibilities are many. To find the correct one you have to measure the volume of urine passed each day, and you can do this yourself. Get a container with fluid volumes marked on the sides. You can find one at a drugstore or hardware store. You can urinate directly into the container or into a bedpan that you empty into the container, and measure the volume. Normally people urinate between 1.5 and 2 liters (1,500 to 2,000 ml; 1.6 to 2.1 quarts; 50 to 67 ounces) in 24 hours. A healthy urinary bladder holds 400 to 500 ml (13 to 16 ounces), so people have to empty their bladders three to five times a day. If fluid intake is high, then the trips to the bathroom are more, but not every half-hour.

If your 24-hour urine total is greater than 3 liters (3.2 quarts, 96 ounces), you have polyuria – the production of excessive amounts of urine. Causes include sugar diabetes, polycystic kidney disease, compulsive fluid drinking, high blood calcium or low blood potassium. It can also be diabetes insipidus, urine overproduction due to lack of a hormone called vasopressin.

If your total volume is in the normal range, then the problem is reduced bladder capacity. Bladder infections, interstitial cystitis or, in men, an enlarged prostate gland are possibilities. Bladder muscle spasms also do it, and that’s what Detrol treats.

I favor diabetes insipidus or interstitial cystitis as prime candidates. The first can be diagnosed with blood tests. The second can be diagnosed with a scope examination of your bladder and by symptoms such as bladder pain. You should see a urologist or a nephrologist.

DEAR DR. DONOHUE: My son is 43. Two months ago, he went for a physical and blood work. The blood tests showed he has too much iron in his blood. His doctor said he had two options: to remove blood or to take medication to lower the blood iron. Is this serious? – B.A.

ANSWER: The illness is hemochromatosis (HE-moe-CROW-muh-TOE-siss). It’s a genetic disease, and an affected person has to have two genes for it, one from the mother and one from the father. The illness causes the body to lose its control over iron absorption. Too much gets into the blood and is deposited in the liver, the heart, the pancreas, joints, the skin and many other places. Liver cirrhosis, diabetes and heart failure can result. Early detection of the illness permits removal of the iron and preserves organs. No damage is done. The simplest way to achieve that is to remove blood periodically. Blood is the body’s warehouse for iron.

You and your husband, all your other children and your son’s children should be checked for this illness.

DEAR DR. DONOHUE: I have stomach carcinoid. Due to it, I flush. I have read things on the Internet about it, but I don’t understand it. Can you simplify it for me? – L.D.

ANSWER: Carcinoid is a rare tumor. These tumors can be found in the stomach, the lung, the small intestine, the appendix and the rectum.

Sometimes carcinoid tumors produce the carcinoid syndrome – episodes of flushing, diarrhea or asthma attacks or all three. The attacks come about because some carcinoid tumors secrete chemicals that cause those symptoms. Carcinoid tumors also can lead to heart-valve problems.

Exertion, some foods and alcohol might provoke an attack. A typical attack lasts from 30 seconds to three minutes. The flushing takes place on the head, the neck and upper chest.

Removal of the tumor is the preferred treatment. The medicine Sandostatin (octreotide) can often suppress symptoms if the tumor cannot be removed.

DEAR DR. DONOHUE: Please tell me what ministrokes are, and how to deal with them. My husband, according to our doctor, has had a couple. – J.T.

ANSWER: “Ministrokes” refers to two different circulatory problems of the brain. One is transient ischemic attacks, and the other is blockage of small brain arteries.

Transient ischemic attacks – TIAs – are temporary losses of brain function due to a short interruption of blood flow to a part of the brain. A person might experience weakness of an arm or leg, have difficulty speaking or become numb in a discrete area of the body. The symptoms usually last for less than 15 minutes and can persist as long as 24 hours, but never longer. Ministrokes of this sort are often warnings that a full-blown stroke is in the offing. Doctors frequently put people who have had a ministroke on aspirin to prevent a full-blown stroke.

The other circulatory problem called a ministroke is the blockage of one or more small brain arteries. Such a blockage causes the death of a tiny section of brain.

Sometimes, with one blockage, no symptoms occur. But as more small arteries become clogged, then memory deficits, clumsiness in walking and trouble using the correct word are examples of symptoms that can arise.

Both kinds of ministrokes are indications for an all-out stroke-prevention program. Blood pressure has to be maintained as close to normal as possible. Smoking must stop. Losing weight, when applicable, is important. If the person has diabetes, strict control of blood sugar is mandatory. Lowering cholesterol is important. And staying as active as possible keeps blood circulating to the brain.