Is My Joint Pain Caused by Rheumatoid Arthritis (RA) or Another Autoimmune Disorder?
Polymyalgia rheumatica (PMR) can become quite severe if not diagnosed and treated immediately, resulting in severe immobility and disability. Once diagnosed, PMR responds well to medications.
There is no specific test to confirm PMR, however, a doctor can use information from the patient’s physical examination, laboratory tests, and diagnostic imaging to arrive at an accurate diagnosis.
Physical Examination and Medical History
A physical examination and medical history can be useful in identifying the signs of PMR. The common findings may include:
- Severe pain and/or swelling in both shoulders are seen in most cases
- Pain in the neck and hip (seen in 50% to 70% of cases1)
- Morning stiffness in affected joints lasting over an hour
- Tenderness in the hip, shoulder, and upper arm muscles
- Fever
PMR almost always occurs in people over 50 years of age.2 Since giant cell arteritis is commonly associated with PMR, a history of headaches, jaw pain, or any blurriness in vision is relevant.
Blood Tests
The common blood tests to help diagnose PMR include:
- High Erythrocyte sedimentation (ESR)—can often be highly elevated and may exceed 100mm/hour in some cases (normal value—<30mm/hour)3
- C-reactive protein (CRP)
- Anemia
- High liver enzymes
These tests are used to identify specific proteins that are released from the areas of inflammation in PMR.
Medical Imaging Techniques
Ultrasound imaging of the shoulders and hips can identify bursitis, synovitis, and tenosynovitis in the affected areas. Inflammation in PMR can result in:
- Subdeltoid bursitis (shoulder bursitis)
- Trochanteric bursitis (hip bursitis)
- Biceps tenosynovitis (tenosynovitis in the upper arm)
- Glenohumeral synovitis (shoulder joint synovitis)
An ultrasound examination can be useful in diagnosing PMR, though they are seldom needed to make the diagnosis. In most cases, the medical history and blood test reports are the most important factors leading to a PMR diagnosis.
In 2012 the European League Against Rheumatism (EULR) and the American College of Rheumatology (ACR) collaborated to develop a classification criteria to diagnose PMR. The classification uses a points system and is outlined below.4
| Required criteria (must be present) | |
|---|---|
| 50 years or older | |
| Bilateral shoulder aching (right and left sides) | |
| Abnormal C-reactive protein and/or erythrocyte sedimentation rate | |
| Clinical criteria | |
| 2 points | Morning stiffness lasting more than 45 minutes |
| 1 point | Hip pain or restricted range of motion |
| 2 points | Absence of rheumatoid factor (RF) and anti-citrullinated protein antibodies (measured using an anti-CCP antibody test) |
| 2 points | Absence of other joint involvement |
| Ultrasound criteria | |
| 1 point | At least one shoulder with subdeltoid bursitis, biceps tenosynovitis, or glenohumeral synovitis; and at least one hip with synovitis or trochanteric bursitis |
| 1 point | Both shoulders with subdeltoid bursitis, biceps tenosynovitis, or glenohumeral synovitis |
With only clinical criteria, a total of 4 points indicates PMR. With clinical and ultrasound criteria, a total of 5 points indicates PMR.
Differential Diagnosis for PMR
Certain disorders can exhibit symptoms similar to PMR. These conditions must be ruled out before PMR can be diagnosed.
- Late-onset rheumatoid arthritis is commonly seen in people over 60 years,5 and can cause sudden and severe joint pain. However, it is more common in the knees, hands, wrists, and feet. Also, there can be significant bone damage in rheumatoid arthritis.
- Remitting seronegative symmetrical synovitis with pitting edema also affects the older age group and produces symmetrical inflammatory symptoms. However, unlike PMR, this condition is more common in males, and the symptoms are mainly limited to the hands, wrists, and feet.
The results from medical history, blood tests, and diagnostic imaging can help a doctor distinguish PMR from other conditions with similar symptoms.
References
- 1.Chung T-Y, Hunder GG, Ilstrup DM, et al. Polymyalgia rheumatica: a 10-year epidemiologic and clinical study. Ann Intern Med 1982; 97: 672-80 And Salvarani C, Macchioni PL, Tartoni PL, et al. Polymyalgia rheumatica and giant cell arteritis: a 5-year epidemiologic and clinical study in Reggio Emilia, Italy. Clin Exp Rheumatol 1987; 5: 205-15 As cited in - Salvarani C, Macchioni L, Olivieri I, Cantini F, Boiardi L. Diagnosis and Management of Polymyalgia Rheumatica/Giant Cell Arteritis. Biodrugs[serial online]. January 1998;9(1):25-32.
- 2.Mackie SL. Polymyalgia rheumatica: pathogenesis and management. Clinical Medicine [serial online]. August 2013;13(4):398-400.
- 3.Salvarani C, Gabriel S, Hunder GG. Distal extremity swelling with pitting edema in polymyalgia rheumatica: Report of nineteen cases. Arthritis Rheum 1996; 39: 73-80.
- 4.Muratore, F., Salvarani, C., & Macchioni, P. (2018). Contribution of the new 2012 EULAR/ACR classification criteria for the diagnosis of polymyalgia rheumatica. Reumatismo, 70(1), 18-22.
- 5.Turkcapar N, Demir O, Atli T, Kopuk M, Turgay M, Kinikli G, et al. Late onset rheumatoid arthritis: clinical and laboratory comparisons with younger onset patients. Arch Gerontol Geriatr. 2006;42:225–31.
