Hormone Assays. Serum concentrations of CRP, IGF-I, IGFBP-3, insulin, hGH, C-peptide, and urinary cortisol will be measured using a high-throughput, continuous random access immunoassay analyzer, Immulite 2000. Briefly, after the sample is incubated with an alkaline phosphatase-labeled reagent, the reaction mixture is separated from the bead by spinning the reaction tube at high speed along its vertical axis. The bound label specific to each analyte is then quantified using the dioxetane substrate to produce light. Amount of light emitted is proportional to the amount of analyte in the sample. Losartan, angiotensin II, renin, and aldosterone will be measured by UTMB Clinical Services.