Patients with hemolytic disorders (e.g. sickle cell anemia or thalassemia) are known to develop pulmonary hypertension. Hemolysis is where red blood cells are destroyed and their contents released into the circulation. It is thought that these red-cell contents cause constriction and thrombosis of the blood vessels in the lungs. Conversely, it is possible that patients with pulmonary hypertension have hemolysis.

In this study we will be drawing blood from a range of patients and normal controls for a panel of blood tests related to hemolysis.

Inclusion Criteria:

One of the following four conditions :

• Pulmonary artery hypertension
• Obstructive sleep apnea with pulmonary hypertension
• Lung transplant candidates without pulmonary hypertension
• Normal Controls

Exclusion Criteria:

• Known hemolytic disorder
• Recent blood loss (<3 months)
• Recent blood transfusion (<3 months)
• Liver disease