The trial will be a double blinded, placebo control trial of two uric acid lowering agents. The endpoints for this trial will be, endothelial function, systemic vascular resistance, plasma renin activity, MCP-1 and CRP. Upon recruitment and informed consent, children will undergo initial screening. This will include medical history, family history, dietary history, review of systems (questionnaire used and validated in pediatric hypertension clinic) and pediatric quality of life questionnaire. They will have a physical exam, casual and ambulatory blood pressure monitoring (see below) and screening laboratory analysis that will include CBC, electrolytes, BUN, Cr, Uric acid, AST, ALT and urinary micro-albumin to creatinine ratio. Children with serum uric acid less than 5.0mg per dl will be enrolled as controls and only have baseline studies at Screening and Visit 1. Children with serum uric acid equal to or greater than 5.0mg per dl will be randomized (in a one to one to one ratio) to receive placebo, allopurinol or probenecid.