A positive antinuclear antibody test may suggest a mixed connective tissue disorder. It is important to exclude the connective tissue disorder scleroderma as it has a high prevalence of pulmonary artery hypertension. Cardiac biomarkers are obtained to rule out myocardial ischemia. Brain-type natriuretic peptide (BNP) and Nterminal prohormone brain natriuretic peptide (NTproBNP) are indicators of right ventricular overload. Brain-type natriuretic peptide 150 pg/mL and NTproBNP >1474 pg/mL correlate positively with an elevated MPAP and PVR. Serological testing can also detect HIV and hepatitis, which are also causes of Pulmonary hypertension.