DEAR DR. DONOHUE: I take blood thinners because I have atrial fibrillation. The one I take is Coumadin. I have to have my blood checked frequently, and it’s most annoying. Is it important that I stay on this medicine? – T.J.

Atrial fibrillation is in first place among contenders for the title of most prevalent heartbeat disturbance. Often it results from high blood pressure, heart valve disorders or an insufficient blood supply to the heart muscle. It can, however, arise on its own.

The heart’s natural pacemaker initiates a heartbeat by discharging a tiny pulse of electricity to all four heart chambers. In atrial fibrillation, the heart has lost its metronomic uniformity, and the heartbeat becomes completely irregular. The upper heart chambers – the atria – not only beat erratically, but they also lose the ability to contract and shoot blood to the lower heart chambers – the ventricles. The ventricles also beat out of sync, but they can still contract and deliver blood to the lungs and the body.

The fibrillating atria look like mounds of quivering gelatin. One consequence of this is a pooling of blood in the atria. Pooled blood is stagnant, and stagnant blood forms clots. That’s one of the most significant dangers of atrial fibrillation.

Bits of the atrial clots can break loose from the main clot and be carried in the circulation to the brain. There they can occlude brain arteries. The result is a stroke.

If a normal heartbeat cannot be restored, then the risk for a stroke is great. For that reason most people with fibrillating hearts must take a blood thinner, and Coumadin is the most popular blood thinner. While on Coumadin, patients have to have their blood checked often to make sure their blood is thin enough but not too thin. I know you’ll agree that this is a small price to pay for stroke protection.

DEAR DR. DONOHUE: I am a sexually active young woman, and I have a trichomonas infection. The doctor said I could take one large dose of medicine or a seven-day treatment with smaller doses each day. I chose the one-time dose. Did I make the right choice? – C.K.

DEAR DR. DONOHUE: I have had a vaginal discharge for three weeks. The doctor has me on treatment for trichomonas. Should my husband be treated, too? – J.C.

Trichomonas (TRICK-oh-MOAN-us) is a single-celled organism that is sexually transmitted. In women, it often leads to a yellow-green, frothy vaginal discharge. Itching and painful urination are usually part of the infection.

The medicine for trichomonas, metronidazole, can be taken in one single large dose, or the dose can be spread over seven days. Either way, the rate of cure is just about the same. Either choice is a good choice.

Men infected with trichomonas seldom have symptoms. They need to be treated along with their partners. If they aren’t, they can reinfect the woman after she has completed her treatment.

DEAR DR. DONOHUE: Does cracking knuckles lead to arthritis later in life? My son constantly cracks his, and it drives me crazy. Nothing I say makes him stop. Perhaps if you said something, he would. – T.T.

I would love to provide you with proof that knuckle-cracking leads to arthritis in the future. I can’t. There is no good evidence of that. Knuckle-cracking gives me the shivers too.

The noise comes from a bubble that forms in joint fluid when a person manipulates the joint. The cracking sound is the bubble bursting.

Son of T.T., do your mother and me a favor. Stop cracking your knuckles. You’re driving both of us crazy.

DEAR DR. DONOHUE: Why do you give lab results in two sets of numbers? – G.H.

Canada follows the International System’s units of blood values. Americans do not. I use both so the answer will be understood on both sides of the border.

DEAR DR. DONOHUE: My mother and two aunts on her side were diagnosed with Alzheimer’s disease. How early should a person start taking medicine to ward off this disease? – E.K.

DEAR DR. DONOHUE: I am a 52-year-old male. My mother’s father and her aunt both died from Alzheimer’s. My father is alive, but he has it. What signs should I look for in myself? What are my chances of getting it? Are there any tests I can take to determine my chances? – H.B.

Right from the start, be aware that medical science does not have all the answers to questions about Alzheimer’s disease, so take my answer to be tentative at best.

The age when a relative develops Alzheimer’s is an indication of how likely it is that a family carries genes that contain the seeds of Alzheimer’s disease. When it makes an appearance at a young age – the 40s – then the influence of genetic factors on its transmission is high. When it comes on later in life, the gene connection is not so clear. Exact predictions cannot be made. As an extreme example, say a mother or father shows signs of Alzheimer’s at age 85. The chances that her or his children will also have Alzheimer’s are slight.

There is no test for Alzheimer’s. Doctors had hoped that testing for a gene called ApoE would predict a person’s susceptibility to Alzheimer’s, but that has not panned out.

Early signs of Alzheimer’s include an inability to learn new information, an inability to recognize familiar faces and a change in personality. An easygoing person changes into a gruff, irascible person. Significant memory lapses are common.

No medicine prevents Alzheimer’s. Memantine, a drug available in Europe, shows a flicker of success. A low-fat, low-calorie diet might delay its onset.

The Alzheimer’s pamphlet contains more information for the many questions left unanswered. Readers can obtain a copy by writing: Dr. Donohue – No. 903, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 U.S./$6.50 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

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.

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