Utility of blood investigations for adults with musculoskeletal symptoms

For advice on the investigation of musculoskeletal conditions in children and adolescents, see Utility of investigations for children and adolescents with musculoskeletal symptoms.

Note: For people with musculoskeletal symptoms, only perform blood investigations if they will support a specific diagnosis or change the course of management, as unnecessary investigations can do harm.

Most rheumatological diseases are diagnosed clinically. For people with musculoskeletal symptoms, blood investigations play a limited role in diagnosis because generally they:

  • are not necessary to make a diagnosis
  • infrequently confirm a suspected (rheumatological) diagnosis.

Consider ordering blood investigations where necessary to support the diagnostic process, without unnecessary testing. Always consider if the investigation result will influence your management before requesting it.

For useful information on the diagnostic process and the utility of investigations in people with diffuse, nonspecific symptoms and no signs of an inflammatory rheumatological diagnosis, see Fatigue guidelines: Diagnostic process.

If indicated by the person’s presentation, the following blood investigations may be useful to support a rheumatological diagnosis:

  • full blood count
  • erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) concentration
  • serum creatine kinase concentration
  • thyroid function tests
  • serum electrolytes (including calcium) and creatinine concentrations
  • serum ferritin concentration
  • blood glucose concentration
  • liver biochemistry.

Avoid repeating the following investigations if they were previously normal because they are commonly re-ordered without assisting diagnosis: serum iron concentration, vitamin B12 and vitamin D concentrations, and thyroid function tests.

A common clinical dilemma is a person presenting with arthralgia, myalgia and a positive antinuclear antibody (ANA) result. An inflammatory connective tissue disease such as systemic lupus erythematosus (SLE) is an unlikely diagnosis if there are no extra-articular features presentAustralian Rheumatology Association (ARA), 2018.

Do not pursue further blood investigations if a diagnosis cannot be found despite the blood investigations listed above; rather, monitor the person clinically for any changes in their condition. Reassure them that a nonprogressive course suggests a benign underlying cause.