The investigators will test our hypothesis and accomplish our objectives by pursuing three Specific Aims:~To investigate the interrelationship between macrophage migration inhibitory factor (MIF) and free T4 in patients with PAH with a working hypothesis that an increased release of MIF into the pulmonary vasculature during cardiopulmonary exercise changes the normal balance between plasma MIF and T4.
The investigators will investigate the interrelationship of macrophage migration inhibitory factor (MIF) and free T4 in patients with PAH.