Screening for pulmonary hypertension (pHTN) has not yet become routine in sickle cell disease (SCD), despite clinical evidence of its high prevalence and associated mortality. Our objectives are to identify clinical conditions and laboratory findings predictive of/or associated with pHTN. One hundred twenty-five adult outpatients with Hb SS, SC, SOArab, Sbeta(0), or Sbeta(+) thalassemia, who underwent echocardiography and/or right heart catheterization due to cardiorespiratory symptoms, were studied. pHTN was identified in 36% (28/77) of SS/Sbeta(0) and in 25% (12/48) of SC/SOArab/Sbeta(+) patients studied. In SS/Sbeta(0) patients, pHTN was associated with low hemoglobin, low GFR, increasing age, no history of treatment with hydroxyurea and a history of leg ulcers, with trends for associations with higher total bilirubin, LDH levels, systolic systemic blood pressure, history of avascular necrosis, seizures, and cerebrovascular events. Twelve (40%) of the SS/Sbeta(0) patients with pHTN had >or= 1+ proteinuria. (P<0.039). The presence of proteinuria correlated with lower GFR and had a high positive predictive value (0.60) for pHTN in subjects with SS/Sbeta(0). The data also provided evidence that pHTN in this population is associated with right heart failure, with echocardiographic evidence of right ventricle enlargement and pericardial effusion. This study confirmed that even relatively mild elevations in pulmonary pressure are associated with high prospective mortality (hazard ratio: 15.9). We concluded that pHTN has a high prevalence in all Hb S related syndromes and is associated with increased mortality in SS/Sbeta(0). Kidney dysfunction, as indicated by proteinuria or decreased GFR, also represents sufficient reason to screen for pHTN.