Smukowska-Gorynia A, et al. - In patients with pulmonary arterial hypertension (PAH) and inoperable chronic thromboembolic pulmonary hypertension (CTEPH), researchers assessed the prognostic impact of neopterin (NP) as well as its association with disease severity. They analyzed blood concentration of NP in these patients vs healthy controls and in relation to clinical parameters and outcome. They found that patients with PAH and inoperable CTEPH had increased NP concentration. They also observed adverse clinical outcomes related to elevated NP concentration in these subjects. NP showed a positive correlation with NT-proBNP, red blood cell distribution width, and right atrium area and inverse correlation with 6-min walking test and peak oxygen consumption.