source: Pulmonary Hypertension Association

Sickle cell disease (SCD), a type of anemia (shortage of red blood cells), is characterized by abnormally shaped red blood cells. Sickle cells (named for the sickle, or oblong, slender shape of the malformed blood cells) have decreased flexibility, meaning they break easily. This results in a number of life-long complications.

PH is an increasingly recognized complication of SCD. Studies show that approximately 30% of screened adult patients with SCD develop mild PH in adulthood. In 10% of patients, the PH is more severe. Recent autopsy studies also suggest that up to 75% of sickle cell patients show changes in the lung tissue at the time of death, indicating the existence of pulmonary arterial hypertension (PAH).

One possible reason sickle cell patients seem to be at risk for developing PH is that increased breakdown of red blood cells within the blood vessels causes inflammation and a decrease of nitric oxide (a substance that causes relaxation of the blood vessels). This causes constriction of the small arteries of the lungs which may lead to PH.