Polymyalgia rheumatica, or PMR, is an inflammatory disorder of unknown cause that affects older adults. Establishing the diagnosis requires the presence of typical symptoms plus laboratory tests showing evidence of inflammation, such as elevated C-reactive protein levels. Although PMR responds rapidly to medication, the nature of the disease requires long-term treatment and follow-up.
Polymyalgia Rheumatica
PMR occurs relatively commonly in older adults, particularly those over age 50, women and Caucasians. The typical symptoms of stiffness and muscle aches usually arise quickly, are worse in the mornings or after prolonged inactivity and preferentially involve the upper arms, neck, thighs and hips. No one knows the cause of PMR, but inflammation of the joints and surrounding tissue plays a key role. PMR responds rapidly to treatment with corticosteroids, sometimes after only a single dose, but continued medication and follow-up are often needed for several years.
C-Reactive Protein
C-reactive protein, or CRP, is a simple blood test that reflects the overall level of inflammation in your body. Produced by the liver, CRP levels in the blood begin to rise within a few hours of your body's reaction to infection, heart attack or surgery. Levels remain elevated as long as inflammation persists, making CRP a useful test for tracking the activity of chronic disorders such as inflammatory bowel disease, some types of arthritis, autoimmune diseases and PMR. Your CRP level drops with successful treatment and decreasing inflammation and rapidly increases again during a recurrence. Another test called the erythrocyte sedimentation rate, or ESR, also reflects your level of inflammation and is sometimes used in place of CRP.
Diagnosing Polymyalgia Rheumatica
Key findings suggestive of PMR include at least two weeks of morning stiffness with typical shoulder or pelvic aching in an adult over 50 years of age. Laboratory testing should show evidence of an active inflammatory response, with either an elevated C-reactive protein or ESR level. No active infections, cancer or other serious conditions such as giant cell arteritis, an inflammatory disorder of blood vessels associated with PMR, should be present. Once your health care provider strongly suspects PMR, she will start daily low-dose corticosteroids and watch for your response. Symptomatic improvement usually occurs quickly, often within a few days, and CRP levels return to normal within four weeks, according to the British Society for Rheumatology. If symptoms persist longer than this, PMR might not be the correct diagnosis.
Monitoring PMR Treatment
Once your PMR symptoms have improved, steroid doses are slowly decreased to the lowest level that keeps you comfortable. Aching and stiffness can come back, and steroid use might be needed for one to three years. During this time, your health care provider will perform regular check-ups looking for recurrent symptoms, any signs of complications or side effects of steroids. Laboratory testing should include a CRP or ESR level to monitor for evidence of inflammation. Although either test will do, a study in the August 2000 issue of "Seminars in Arthritis and Rheumatism" reported that ESR was somewhat better at predicting recurrences of PMR symptoms than the more sensitive CRP.
References
- American College of Rheumatology; Polymyalgia Rheumatica; William P. Docken MD
- Lab Tests Online: C-Reactive Protein
- "Rheumatology"; BSR and BHPR Guidelines for the Management of Polymyalgia Rheumatica; Bhaskar Dasgupta, et al.; November 2009
- "Seminars in Arthritis and Rheumatism"; ESR and CRP in the Evaluation of Polymyalgia Rheumatica; Fabrizio Cantine, et al.; August 2000
