Blood test and immunology
Routine biochemistry, haematology and thyroid function tests are required in all patients, as well as a number of otheressential blood tests. HIV testing is mandatory.
Thyroid disease is commonly seen in PH and should always be considered, especially if abrupt changes in the clinical course occur).
Systemic sclerosis is the most important connective tissue disease (CTD) to exclude because this condition has a high prevalence of PH. However, autoantibody testing should be performed only if collagen vascular disease is suspected on clinical grounds:
- Anti-Scl-70 antibodies for progressive systemic sclerosis of diffuse type
- Anti-centromere antibodies are typically positive in limited scleroderma as are other anti-nuclear antibodies including dsDNA, anti-Ro, U3-RNP, B23, Th/To and U1-RNP.
- In the diffuse variety of scleroderma, U3-RNP is typically positive.
- In individuals with systemic lupus erythematosus, anti-cardiolipin antibodies may be found.
- Anti-dsDNA and anti-SM for systemic lupus erythematosus
- Rheumatoid factor and anti CCP for rheumatoid arthritis
- However, antinuclear antibodies are nonspecific since they are present in up to 40% of patients with PAH, usually in low titre (1:80) .
Up to 2% of individuals with liver disease will manifest PAH and therefore liver function tests and hepatitis serology should be examined if clinical abnormalities are noted. The presence of liver cirrhosis is suggested by:
- hematologic abnormalities (macrocytosis, thrombocytopenia),
- electrophoresis (hypalbuminemia, hypergammaglobulinemia)
- morphologic changes on ultrasound or computed tomography.
Screening for possible chronic hepatitis (hepatitis S antigen, anti-HBc-IgM, anti-hepatitis C antibodies) may be indicated. Overall liver function can be assessed by determining factor V levels which reflects liver function even in anticoagulated patients. Elevated bilirubin levels greater than 36 µmol/l in presence of PH are indicative of severe cardiac cirrhosis and associated with poor survival after lung transplantation.
Genetic testing has still no management implication in the present clinical management, however may provide useful information in the future and should therefore be considered to be done within clinical trials or registries.