Erythrocyte Glutamine Level Relation to Pulmonary Hypertension Risk in Beta Thalassemia Major Children

Inclusion Criteria: * Established diagnosis of Thalassemia. * PH risk documented by doppler echocardiography, defined as tricuspid regurge velocity (TRV) equal to or greater than 2.5 m/s Exclusion Criteria: * Acute crisis or hospitalization within 1 month of enrollment * Hepatic dysfunction (SGPT greater than 3X normal) * Renal dysfunction (Creatinine greater than 2X normal) * Patients on sildenafil (Viagra), calcium channel blockers or other drugs for the control of PH.