Pilot clinical trial of arginine treatment in sickle cell pulmonary hypertension. Baseline measurements were made of estimated pulmonary artery systolic pressure by Doppler echocardiography in 10 adults with sickle cell disease. After treatment with oral arginine (0.1 mg/kg 3 times a day for 5 days), measurements were repeated and had decreased by a mean of 15% (P = .002).⁸