Definition of high blood pressure: We will use the guidelines for blood pressure measurement that have been adapted from the Update on the Task Force Report (1987) on High Blood Pressure in Children and Adolescents [22]. Hypertension will be defined as >95th percentile blood pressure for age, height percentile (rounded to the nearest of 5th, 10th, 25th, 50th, 75th, 90th, or 95th percentile of height above the patients actual height) and gender. Each blood pressure measurement will be the mean of 3 right arm readings, taken with an mercury sphygmomanometer at least three minutes apart with the patient sitting upright and relaxed. For the purposes of the study, to be defined as hypertensive, a patient will need to have mean systolic or diastolic blood pressure >95th percentile on three consecutive occasions, on separate days over at least a 1 week period. Patients with previously confirmed hypertension will be reconfirmed during the screening period.