DEAR DR. DONOHUE: I have had psoriasis for 10 years. I am 42. My skin stays pretty well controlled, but I have developed stiffness and pain in my back. I thought it was just an ordinary backache. I mentioned it to my dermatologist, and he sent me to a rheumatologist. She says it’s from my psoriasis. How so? I have never heard of that. – R.S.

Everyone is familiar with the skin disorder psoriasis. Few know about psoriatic arthritis, arthritis associated with this skin problem. The psoriasis-associated arthritis affects from 5 percent to 30 percent of those with skin psoriasis. Let me make two points right off. First, people with psoriasis can have other kinds of arthritis, like osteoarthritis and rheumatoid arthritis. Second, the severity of skin psoriasis doesn’t affect the severity of psoriatic arthritis. In other words, minor skin psoriasis can generate major joint arthritis.

Any joint can be the target of psoriatic arthritis. The back is often targeted, as are the fingers, which swell and look like sausages. For a few people, psoriatic arthritis is quite disabling.

Nail involvement is common with joint involvement. The nails have pits that look like they’ve been made by a needle. The nails also often separate from their underlying skin.

NSAIDs – nonsteroidal anti-inflammatory drugs – are used for mild psoriatic arthritis. Naproxen, ibuprofen and indomethacin are such drugs. Methotrexate controls more-severe arthritis. A raft of newer drugs has made an appearance. Enbrel is one example.

DEAR DR. DONOHUE: I cheated on my wife one time. Shortly after, we were both informed that we have HPV, human papillomavirus. My wife has always wanted children. Is this still possible with HPV? – R.S.

Human papillomavirus is a very common infection. The infection causes genital warts in men and women. A handful of the more than 100 strains of HPV cause cervical cancer. Most genital warts resolve on their own.

The infection doesn’t interfere with having children.

The pamphlet on HPV and herpes virus explains these infections in detail. To obtain a copy, write: Dr. Donohue – No. 1202, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I had a bad case of bronchitis, and my doctor put me on Levaquin. My cough stopped. After I finished the medicine, my right heel cord started to hurt. I saw another doctor, who says it came from the Levaquin, and he said my tendon might tear apart. Why is such a drug approved for use? – L.F.

Levaquin belongs to the quinolone drug family of antibiotics. Cipro, Noroxin, Floxin, Avelox and Maxaquin are other members. They’re very useful medicines. All medicines have side effects. The quinolones can cause tendon inflammation in a few people, and the Achilles tendon, the heel cord, is the tendon most often affected. The inflammation can occur during use or after the medicine has been stopped. In an extremely small number of people, the tendon ruptures.

I don’t mean to brush off this side effect as nothing. It happens only to a very small number. Such a side effect has to be tolerated in order to obtain the drug’s benefit – cure of an illness.

DEAR DR. DONOHUE: Is the DNA of identical twins identical, or do they have their own DNA? – P.H.

Identical twins have the same genes as each other and, therefore, the same DNA. Identical twins occur when a single fertilized egg splits into two embryos.

The fact that these twins have the same DNA makes them most useful when it comes to studying genetic (inherited) illnesses.

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

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