Question: what is the maximum amount of blood that can be drawn?
Answer: No more than 2.5% of total blood volume may be drawn solely for research purposes (no benefit to the subject) within a 24-hour period. This is generally 2 ml/kg. No more than 5% of total blood volume may be drawn solely for research purposes (no benefit to the subject) within a 30-day period. This is generally 4 ml/kg.