The blood results in a patient with PAH can point to a number of particular causes.
1. Full blood count. This can show an elevated haemoglobin secondary to hypoxaemia especially in congenital heart disease. It can also be elevated in myeloproliferative disorders which can be a marker of Jak2 positive myeloproliferative disorder. Anaemia can result in elevated cardiac output which can cause elevated pulmonary artery pressures.The platelet count can be low in patients who have splenomegaly in portopulmonary hypertension.
2. Urea and electrolytes. A low sodium level has been implicated as a prognostic marker in PAH. Patients with chronic renal failure can have PH for a number of reasons including left heart dysfunction, anaemia and PAH (Group 5)
3. Liver function. These can be abnormal in patients with portopulmonary hypertension and cirrhosis. These results are important when considering treatments for PAH which might have liver toxicity.
4. Thyroid function: These can be abnormal and there is a strong association between autoimmune thyroid disease and that of idiopathic PAH.
5. Autoimmune screen: There is a strong association of PAH with limited cutaneous sclerosis (anti-centromere positive), mixed connective tissue disease (anti-Ro/La positive) and lupus (anti-double stranded DNA positive). Less commonly are links with rheumatoid arthritis and large vessel vasculitis.
6. Virology screen: There is an association with hepatitis C and PAH, but both hepatitis B and C can cause liver disease and portal hypertension can lead to portopulmonary hypertension.
7. NT-proBNP: This is a surrogate marker of cardiac function and is elevated in PAH.
Links to further reading:
- The Joint Task Force for the Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS). 2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. European Heart Journal (2016) 37, 16
- Monahan K et al. Reproducibility of intracardiac and transpulmonary biomarkers in the evaluation of pulmonary hypertension. Pulmonary circulation 2013;3: 345-9
- Curnock et al. High prevalence of hypothyroidism in patients with primary pulmonary hypertension. Am J Md Sci 1999;318:289