How should I prepare for bloodwork?
Most hormone and metabolic panels require an 8-12 hour fast, morning draw (especially testosterone), water-only hydration, and avoiding intense exercise 24-48 hours prior.
Full answer
Most comprehensive panels are best drawn after an 8-12 hour fast (water only) in the morning. Testosterone in particular should be drawn between 7 and 10 AM, when levels are highest. Avoid intense exercise in the 24-48 hours before the draw — muscle markers (CK, AST, ALT), inflammation markers (hs-CRP), and even hemoglobin can transiently shift. Hold biotin supplements for 72 hours when feasible, as biotin interferes with several immunoassays. Take prescribed medications unless your provider gives different instructions. Hydrate well — dehydration concentrates many markers and can produce misleading results.
Educational. Not a substitute for individualized provider review.
- Biomarker panel — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29