DEAR DR. DONOHUE: Nine months ago, our son, 42, had a deep-vein thrombosis. The clot was in the calf and thigh vein. He was given an anticoagulant and the clot was surgically removed, but surgery was only partly successful. Some of the clot remains in his leg veins. He continues to take Coumadin and is told it may take a year for the clot to dissolve. His calf is often swollen and painful. Can you suggest any additional treatment? – M.T.

ANSWER: For readers unfamiliar with this problem, some definitions are necessary. Thrombophlebitis (THROM-boh-flea-BITE-is) is a clot in a vein. “Thrombo” means “clot,” and “phlebitis” is vein inflammation. The leg is the common site for it to happen.

A person on bed rest after surgery (especially knee and hip surgery), who is sitting for prolonged times during a car or plane trip, taking birth-control pills or suffering trauma is at risk of getting thrombophlebitis.

Clots in the deep veins of the leg, the ones you cannot see, are the dangerous kind. Bits of those clots can break away from the main clot and be carried in the circulation to the lung, where they can plug a lung blood vessel. That’s called a pulmonary embolism, and it can be deadly.

Clots in leg veins cause the overlying skin to turn red and become tender. The leg swells and is painful. Ultrasound examination of the veins establishes the diagnosis.

Anticoagulants are the treatment. They don’t dissolve the clot, but they keep it from growing larger and they prevent the chance of a pulmonary embolus. In time, a canal burrows through the clot, and blood flow is re-established or blood finds alternate routes to leave the leg. It takes months for this to occur. Nothing speeds the process. Time is the medicine of choice.

A large number of people develop what’s called the post-thrombotic syndrome after thrombophlebitis. The leg remains swollen and painful. Compression stockings and frequent leg elevation minimize this complication.

The peripheral vascular disease booklet discusses this illness, its treatment and outlook. Readers can order a copy by writing: Dr. Donohue – No. 109, 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: For all the obvious points you discussed about gout, I am perplexed that you failed to mention the most serious part. The same crystals that invade the joints can invade the kidneys, and this has killed many an unsuspecting sufferer. Shame on you. – J.S.

ANSWER: When kidney failure happens to a gout patient, it usually happens for the same reasons it happens to patients without gout – high blood pressure, for example. However, gout can cause two serious kidney diseases. One is gouty nephropathy. Uric acid crystals, the basis of gout, infiltrate the kidney and kidney blood vessels, and can cause them serious damage.

Gout also can cause a special kind of kidney stone – uric acid stone. Ten percent to 40 percent of gout patients develop such a stone.

If uric acid levels are lowered, these complications can be avoided.