How is giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) diagnosed?
The diagnosis of GCA is based on the presence of previously noted symptoms and/or the finding of abnormal blood flow in the arms, legs, or aorta; tenderness of the scalp or temples; visual abnormalities; and a high ESR. The ESR (erythrocyte sedimentation rate) is a blood test that simply measures the rate at which red blood and other cells settle towards the bottom of a tube. A rapid or high rate usually correlates with ongoing inflammation. While the test is good, it is not perfect, and the diagnosis of GCA may sometimes be made even when this test is normal.
Once the diagnosis has been made, treatment should be started as soon as possible.
If the diagnosis is suspected, but less convincing features are present, a temporal artery biopsy may confirm the diagnosis. The biopsy is taken from a part of the artery located in the hairline, in front of the ear. The biopsy is helpful in most cases, but in some individuals it may be negative or normal, even though the disease is present.
PMR is diagnosed after:
- Careful evaluation of a person’s medical history with an emphasis on the presence of pain, aching and stiffness in the shoulder, pelvic, and hip regions
- A complete physical exam. During the exam, the presence of common PMR features and those of other possible illnesses are evaluated.
- Excluding the possibility of other illnesses. Blood test results may show distinct abnormalities typical of other diseases that would suggest different diagnoses.
- Evaluating the results of blood tests. A high erythrocyte sedimentation rate (ESR) is common among patients with PMR.
- Quick recovery and disappearance of symptoms after treatment with low-dose corticosteroids.