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Fahmida's investigations

Fahmida has widespread musculoskeletal pain but her history doesn't suggest an inflammatory cause. From her history you might suspect she has fibromyalgia.

Investigations are of limited use in ‘ruling in’ fibromyalgia, but may be helpful in excluding other diagnoses. The following investigations might be considered in this case:

  • FBC
  • U&Es
  • LFTs
  • bone profile
  • ESR
  • CRP
  • thyroid function tests
  • HbA1c
  • creatine kinase
  • ferritin
  • 25-hydroxy vitamin D
  • urine dipstick tests for blood, protein and glucose.

The following tests aren't routinely indicated:

  • rheumatoid factor (RF)
  • anti-cyclic citrullinated peptide (anti-CCP) antibodies
  • antinuclear antibody (ANA)
  • anti-neutrophil cytoplasmic antibody (ANCA)
  • immunoglobulins (Igs).

There's no added benefit to checking rheumatoid serology as these tests aren't sensitive or specific enough to rule a diagnosis of inflammatory arthritis in the primary care setting.

Fahmida's test results

Test Results
FBC Hb 109 g/L
MCV 79 fL
WBC 7.2 x 109/L
Platelets 310 x 109/L
U&Es Normal
LFT Normal
Bone profile Normal
ESR 36 mm/hour
CRP  6 mg/L (Normal)
Thyroid function test (TFTs) Normal
HbA1c 39 mmol
Creatine kinase (CK) 198 U/l
Ferritin  11 microg/L 
25-hydroxy vitamin D 10 nmol/L 
Urine dipstick tests for blood/protein/glucose Normal

Fahmida has a mild microcytic anaemia and low ferritin – this would suggest an iron deficiency picture. She also has a low vitamin D level.

Her ESR is slightly raised. This is unlikely to be significant and could be related to her anaemia. Her CRP is normal, which helps to put the raised ESR in context as a likely incidental finding.

Vitamin D and chronic widespread pain

There's no evidence linking chronic widespread pain in the general population to vitamin D deficiency so it shouldn't be tested routinely.

Routine checking of baseline vitamin D levels isn't indicated unless:

  • you suspect the patient may be deficient
  • bone profiles are abnormal
  • there are additional physical signs.

In at risk populations, where vitamin D deficiency is suspected, then it's reasonable to check vitamin D levels and/or consider an empirical trial of vitamin D therapy according to local guidelines.

Read more about groups at risk for vitamin D deficiency.

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Investigations for musculoskeletal pain

Man having an injection in his arm

Investigations can be most useful to maximise the benefit of the patient's first outpatient appointment and to add certainty to a case that you think is non-inflammatory or manageable in primary care.

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