Small Print:Blood film, serology, CXR, bone scan, bronchoscopic biopsy or nodal aspiration.
FBC, ESR/CRP, blood film: WCC and ESR/CRP raised in acute inflammation and infection. Anaemia of chronic disease may be seen, and blood film will reveal sickle cell.
Autoantibodies: Rheumatoid factor is positive in most cases of RA (if negative, consider measuring anti-CCP), but is also positive in many autoimmune diseases and chronic infections; antinuclear factor is positive in 98% of cases of SLE but a similar result is obtained in 30% of cases of RA and also in many other diseases.
Urinalysis: May reveal proteinuria or haematuria if there is renal involvement in connective tissue disease.
U&E: To check for renal failure via renal involvement in multisystem connective tissue disease.
HLA-B27: A high prevalence in spondoarthritides.
Serology: May be useful to diagnose viral, or atypical systemic, infections. ASO titres, if rising, suggest recent streptococcal infection (e.g. in rheumatic fever).
Joint X-rays: Hand X-rays may show characteristic features helping to distinguish between RA and psoriatic arthritis; pelvic and lumbar spine X-rays may show the typical changes of ankylosing spondylitis (if negative, and clinical suspicion high, a bone scan may be helpful); X-rays of affected joints may confirm clinical diagnosis of OA.
CXR: May reveal lung malignancy.
Synovial fluid analysis: Helps distinguish inflammatory from infective and crystal arthropathies.
Bronchoscopic biopsy or nodal aspiration: For sarcoidosis.
The connective tissue diseases can all affect almost every organ system. Take a full history so as not to miss a clue or complication.
Check the skin as this may contribute to the diagnosis (e.g. scaly rash in psoriasis, butterfly rash in SLE, thickening of skin in sclerosis).
Don’t overvalue autoimmune blood tests. Most diagnoses of arthritis are clinical, blood tests simply providing confirmatory or prognostic information.
Suspect Reiter’s syndrome in a young male with an inflammatory oligoarthritis of the lower limbs.
An insidious onset of symmetrical polyarthritis in the 30–50 age range, with early morning stiffness, pain and swelling of hands and feet, suggests RA.
Pain in the wrists and ankles of a middle-aged or elderly smoker with clubbing and chest symptoms strongly suggests hypertrophic pulmonary osteoarthropathy caused by underlying lung cancer.
Don’t overlook the patient’s occupation as this may be relevant in certain cases – for example, in vets and farm workers, brucellosis and Weil’s disease are possible infective causes.
The experts behind Pulse Reference are Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse’s editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.
This website is for clinical guidance only and cannot give definitive diagnostic information. Practitioners should work within the limits of their individual professional practice, seek guidance when necessary and refer appropriately.
The AI platform ChatGPT has assisted in the creation of some of the content published as part of Pulse Reference. Dr Hopcroft and Dr Freeman have then thoroughly reviewed the content to ensure its timeliness and reliability.