Investigations
1st investigations to order
full blood count
Test
There may be anaemia of chronic disease or iron-deficiency anaemia.
There may be a reactive thrombocytosis.
There may be peripheral fragmentation of red blood cells (associated with systemic disease), but this is rare except when occurring in scleroderma renal crisis.
Result
may be diminished red blood cells or thrombocytosis
serum creatinine
Test
Baseline renal function determination serves as future reference, as some of these patients are at risk of scleroderma renal crisis (worsening diffuse systemic sclerosis).
Result
normal or elevated
serum antinuclear antibody
Test
Negative test does not rule out disease, and a positive test is non-specific.
Centromere and nucleolar patterns, if present, may be suggestive of disease.
Result
may be positive
serum extractable nuclear antigens
Test
Scl 70 or topoisomerase associated with diffuse systemic sclerosis.
Uncommon in other diseases.
May occur in some patients with systemic lupus erythematosus.
RNA polymerase III may be present.
Result
may be positive
serum erythrocyte sedimentation rate (ESR)
Test
ESR may be elevated and is associated with a worse prognosis.
Result
may be elevated
echocardiogram
Test
Pulmonary artery (PA) pressure is increased.
Often gives false positives (overestimating the PA pressure) or false negatives (underestimating the PA pressure).
Result
may demonstrate right heart enlargement
pulmonary function tests (PFTs)
Test
PFTs are done at initial evaluation of the patient.
Low diffuse capacity for carbon monoxide (DLCO) is suggestive of pulmonary arterial hypertension (PAH) and may occur quite early in PAH.
Combination of diminished DLCO and forced vital capacity (FVC) precedes interstitial lung disease.
Result
may show diminished carbon monoxide diffusion or FVC
Investigations to consider
peripheral blood smear
Test
If there is suspected scleroderma renal crisis, or increasing hypertension, there may also be intravascular haemolysis.
Result
red blood cells can appear fragmented
anti-centromere antibody
Test
Presence of anti-centromere antibody is associated with a favourable prognosis.[19]
Result
may be positive
high-resolution CT chest
Test
Performed to establish baseline imaging. Test is repeated if there is a decline in pulmonary function or there are new symptoms that could indicate development of interstitial lung disease.
Result
normal or non-specific interstitial pneumonia
oesophageal manometry
Test
In general, manometry is not diagnostic.
Result
may demonstrate poorly coordinated peristalsis, diminished strength of contractions
Use of this content is subject to our disclaimer