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Medical mystery: Why did ankle hurt so much?

He was a big guy, nearly 300 pounds, so when his left ankle began hurting, the first thing he thought was how much he was asking of it. He'd had a similar pain in his other ankle in the past, even though he swore he hadn't tripped, fallen, twisted, or hurt either one.

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He was a big guy, nearly 300 pounds, so when his left ankle began hurting, the first thing he thought was how much he was asking of it. He'd had a similar pain in his other ankle in the past, even though he swore he hadn't tripped, fallen, twisted, or hurt either one.

An orthopedist had sent him to physical therapy the first time, but that only made it much worse. The pain was so severe any movement of the joint was agony, never mind trying to walk on it. Eventually, the pain went away, but now it was his left ankle, which had begun hurting two days ago and was getting worse.

He was in his mid-30s and healthy, aside from his weight. He hobbled into my exam room, terribly uncomfortable as he tried desperately not to let his left foot touch the ground. He had no fever or skin rashes. His other joints were completely normal, but the top of his left foot was slightly red and exquisitely tender. He winced whenever I touched it, grabbing the table and gritting his teeth as I moved his ankle around. It was a bit warm to the touch, but there was no bruising or bony deformities. The pulse in both feet was normal, meaning he had good blood flow, and he could feel both a pinprick and light touch, which meant the nerves were intact.

But his pain was completely out of proportion to my findings.

I thought about several kinds of arthritis. Osteoarthritis and rheumatoid arthritis typically involve multiple joints at the same time, usually small joints in the fingers, hands, and toes, though ankles could be affected. Could the joint be infected? I'd expect him to be sicker, possibly with a fever, and the joint to be more than just a little red and slightly swollen. Could he have hurt it without knowing? Possible, though not likely. Could he have a tumor in the bone either causing the pain directly or producing a so-called pathologic fracture (a broken bone from minor trauma is not usually enough to produce a fracture)? Perhaps, but it was an odd location for that.

Another thought came to me, and I ordered a blood test.

The solution:

I ordered a uric acid level, which came back quite high at 12.8 (normal range is 3.6 to 8.3) Although I couldn't be absolutely certain of the diagnosis without needling the joint to obtain fluid for examination, I was confident my patient had gout.

Acute gouty arthritis occurs when uric acid crystals form inside a joint and are then attacked by inflammatory white blood cells. High uric acid levels and cooler temperatures result in the formation of these crystals, whose structure is that of microscopic needles. When white blood cells try to do their job of phagocytosis - literally "eating" the crystals, which they sense as debris in the joint - the crystals puncture the blood cells. That spills powerful enzymes that are supposed to stay safely contained in vacuoles (a kind of bubble) within the blood cells into the joint space, causing severe inflammation.

Gout has been around for thousands of years. Some of the classic risk factors include male gender, age between 30 and 60, obesity, and overindulgence in meat, seafood, and alcohol. The classic location for acute gouty arthritis is the base of the big toe, although other joints can be affected.

The acute attack is treated with powerful anti-inflammatory medications, which is what I gave my patient. But even without treatment, the attack subsides on its own in a few days or weeks. The best way to prevent attacks is with daily medication to lower the uric acid level, which tends to be genetically and hormonally mediated. Estrogen lowers it, which is why women are less susceptible than men. Losing weight doesn't help the uric acid situation, though avoiding the rich foods that precipitate gout can also produce weight loss.

Once my patient's attack resolved, I offered him medication to prevent future attacks. He agreed with enthusiasm.