Morbidity of sickle cell trait at high altitude.

A Caucasian with sickle cell trait (54% A, 43% S hemoglobin) had symptoms and signs of chronic hemolytic anemia as well as splenic infarction while living at very high altitude (in excess of 2,800 m). Trips from sea level back to high altitude repeatedly precipitated pulmonary infarctions. All symptoms and evidence of hemolysis resolved at low altitude.