Question: I am interested in learning about the body effects of pernicious anemia, on the heart, for example. Can you send me some info on this?

- Mrs. L.L.H.Answer: Pernicious anemia results from inadequate absorption of vitamin B-12 through the digestive tract lining. Unlike other ingested vitamins, B-12 doesn't magically slip through into the bloodstream unaided. Your stomach makes a certain "intrinsic factor" to take it by the hand and guide it across the wall of the digestive tract and to the bloodstream and thence to places where it is in high demand. Those demand sites include bone marrow (where B-12 helps make red blood cells) and nerve cells (where it helps preserve neural health).

In pernicious anemia, a lack of intrinsic factor interrupts B-12 absorption. Bone marrow red blood cell production lags, and the patient develops signs of nerve disruption and spinal cord disarray. Some patients begin complaining of leg pains and unsteady walking gait. Digestive tract signs emerge, including a red and sore tongue.

Vitamin B-12 deprivation provides the more general signs expected in any kind of anemia, such as weakness, fatigue and light-head-edness. People with existing heart disease might be short of breath and suffer pains of angina pectoris. That's not surprising, since any red blood cell shortage translates into a shortage of the vital oxygen molecules they carry along with them.

You treat pernicious anemia with periodic B-12 injection, bypassing the inoperative stomach route to the bloodstream.

The vitamin report I'm sending you includes deficiency states. Other readers can order a copy of the report by writing: Dr. Donohue - No. 35, Box 5539, Riverton, NJ 08077. Enclose a long, self-addressed, stamped (52 cents) envelope and $3.

Question: Last year, my ECG showed PVCs and couplets. I now have splinter-looking dark streaks under my left fingernails. Can you comment?

- B.S.

Answer: "PVC" stands for premature ventricular contraction. It's an extra heartbeat that comes a bit earlier than it should. A couplet is a pair of consecutive PVCs. The next beat produces a thud sensation, which is the extra strong contraction needed to pump an inordinate volume of blood.

A PVC, even a couplet, is not serious if the heart is essentially healthy. If the beats are disruptive, the doctor can suppress them with medicine. Most often, no treatment is the best treatment.

The splinter streaks under the nails can be but one sign of heart disease, sometimes indicating heart valve infection. You should report them to your doctor and be re-examined if necessary, especially considering your history of heart irregularity.

Question: You have discussed carpal tunnel syndrome in the past, but I took no heed. Now I have the problem myself. The hand is painful, and my doctor suggests surgery. Is that the usual way out?

- K.N.

Answer: Carpal tunnel syndrome is impingement of the wrist nerve. It is being squeezed inside its passage to the hand.

The impingement causes pain in the thumb and middle and index fingers, especially at night.

If splinting and medicine do not help, then surgery can be done to free the tissue.

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 at P.O. Box 5539, Riverton, NJ 08077.

North America Syndicate Inc.