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Dear Dr. Roach Your recent column featured polymyalgia rheumatica and prednisone. Would you please elaborate on how polymyalgia rheumatica can be linked to giant cell arteritis, and the consequences of not having a proper diagnosis in this regard? I had polymyalgia rheumatica two years ago with giant cell arteritis following almost immediately. This was promptly recognized by my primary doctor, confirmed by biopsy and treated with prednisone. It is hard to think that the painful upper arms and hips of polymyalgia rheumatica could lead to the instant blindness of giant cell arteritis if not diagnosed quickly enough. — G.N.

Answer • Giant cell arteritis, also called temporal arteritis, is a condition associated with polymyalgia rheumatica that is certainly worth talking about. While only 10% to 15% or so of people with polymyalgia rheumatica will develop temporal arteritis, it’s dangerous, sometimes overlooked and has a rare permanent complication that you’ve already alluded to.

Giant cell arteritis is not generally seen in people under 50: It’s most common in people in their 70s. Women are affected more often, and those with a Scandinavian background are particularly at risk.

Fever, fatigue and weight loss are nonspecific symptoms but they are prominent in giant cell arteritis. Headache, especially a new headache, is a big red flag. The other suggestive symptom is “jaw claudication”: a sensation of difficulty chewing after doing so for a while, relieved by rest.

When all the symptoms are present in a person with polymyalgia rheumatica, the diagnosis is easy. Unfortunately, some people have only nonspecific symptoms, and it requires a sharp doctor with a high index of suspicion to consider the diagnosis.

Blood tests usually show significant anemia and profoundly elevated ESR and CRP, which stand for erythrocyte sedimentation rate and C-reactive protein, respectively. Both are measures of inflammation. Only 4% of people will have normal blood results. Since no test is perfect, making the diagnosis requires excellent judgment.

The feared complication is vision loss, which is usually painless and sudden, and can be partial or complete. It may happen in one or both eyes, and happens in 10% to 25% of cases. For this reason, there is urgency in making the definitive diagnosis, by temporal artery biopsy. This must be done quickly when the suspicion is high enough. Ultrasound is being evaluated as a possible replacement for biopsy, but biopsy remains the definitive test.

In cases where there is high suspicion, a person is usually started on high-dose steroids while a biopsy is being planned. The biopsy will remain positive for at least two weeks after starting steroids, and since vision loss can be prevented by steroids, these should be started right away when the diagnosis is likely.

Dear Dr. Roach • After reading your recent column on mercury, I wonder how dangerous mercury amalgam for cavity fillings is. I’d guess that the amount of metallic mercury ingested is insignificantly small and of no consequence to overall health. But is it better to replace that type of filling with newer, less-toxic fillings? — J.G.

Answer • Many studies have looked at potential health harms to dental fillings using mercury-containing amalgam, and the consensus is that they are very safe, and that there is no good reason to remove them.

A toxicologist also wrote to me after the mercury column to remind me that metallic mercury can be absorbed through the skin and thus mercury, such as from a broken thermometer, should never be played with and should be properly disposed of.

Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.