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Polymyalgic Syndrome/Systemic Inflammatory Disease
- A doctor is often faced with the challenge of investigating a patient with the effects of chronic systemic inflammation without obvious cause. There are a multitude of potential causes however many will be associated with specific symptoms and signs that will dictate a sequence of investigations which lead to a diagnosis.
- The following outline is intended as a guide to investigation in those patients without specific symptoms and signs. It should be emphasized that in up to 25% of patients demonstrating chronic systemic inflammation no diagnosis is made.
- The major pro-inflammatory cytokines (IL-1, TNF, IL-6) can produce polymyalgic symptoms so the diagnosis of polymyalgia rheumatica should be made with caution and only after careful consideration of other potential causes.
- The list below is to be used as a prompt for the consideration of possible diagnoses and how they might be investigated.
Definition
Symptoms of diffuse, often ill-defined muscle and joint pain and stiffness or non-specific malaise associated with raised acute phase proteins and the anaemia of chronic inflammation (usually normochromic normocytic but may be microcytic).
Clinical Assessment
Clinical assessment with frequent reviews should be the main guide to investigation.
Differential Diagnosis
- Infections (e.g., bronchiectasis, bacterial endocarditis, abdominal abscess).
- Malignancy (especially renal cell carcinoma and lymphoma).
- Connective tissue disease/primary necrotizing vasculitis (consider systemic onset rheumatoid arthritis, polymyalgia rheumatica, giant cell arteritis, granulomatosis with polyangiitis (GPA, formerly called Wegener's granulomatosis) and other small vessel vasculitides).
- Metabolic disorder (thyroid disease, hypopituitarism, adrenal insufficiency).
- Toxin/drug (consider all drugs the patient is on and minimize their use as far as possible).
Investigations
- CBC + diff.
- CRP or ESR.
- Na, K, creatinine, urate, Ca, PO4, alb, bili, ALP, AST, ALT.
- CK, thyroid function tests.
- Urinalysis including microscopy.
- Blood cultures (x3 sets with 10 mL of blood per bottle).
- Urine culture, including TB if unexplained pyuria.
- Chest X-ray (if evidence of chronic lung disease consider chronic pulmonary sepsis and further imaging).
- CT abdomen and pelvis (renal cell Ca, lymphoma, abscess, signs of infection).
- Serology - ANA, ANCA, rheumatoid factor, anti-cyclic citrullinated peptide (anti-CCP) antibodies. Serum protein electrophoresis, immunoglobulins, and serum free light chain analysis.
- Tests for TB.
- Temporal artery biopsy.
- Bone marrow examination for leukaemia, myelodysplasia, and TB culture.
Note: Older persons are often affected by what appears to be an age related “low grade pro-inflammatory state”. It is unclear whether this “pro-inflammatory state” is primarily an age related process or secondary to accumulated morbidities, e.g., cardiovascular disease. Not infrequently acute phase proteins such as CRP will be 4-5 times the upper limit of the reference range compared to a younger age group. Also women suffering from abdominal obesity may have an elevated CRP (usually <15-20 mg/L) with no other explanation.
Topic Code: 3737