- Blood (about 1½ tablespoons) will be drawn. You must fast, have nothing to eat or drink but water for 12 hours before these visits. These samples will be sent to the University of Houston for analysis. Any remaining blood samples will be stored for future testing on biomarkers. We will also request your recent blood results from your doctor in order to compare those results with the blood samples we collect from you. You will not be informed of any findings from the blood tests.