Blood plasma provides advantages in identifying the presence of certain peptide hormones such as rHGH or rIGF-1. There are existing population based reference guides for clinical hematological tests. It reduces the possibility of manipulation of samples. Blood analysis requires the handling of blood which exposes technicians to blood born viruses making the practice much more hazardous than urine analysis. It requires preparation and the refrigerated transport of the sample.
Reference ranges for various peptide hormones are yet to be established.
The concentrations of certain compounds, in particular anabolic steroids, are much greater in urine than in blood. Autologous blood doping or the administration of EPO or ones own blood, cannot be reliably detected. Concentrations of drugs with low molecular weights are lower in blood than in urine by a factor of 100 - 1000. Additional complications arise about blood testing of minors, who make up a sizable portion of competitive athletes. They propose that this fair competitor would need to consider six issues when weighing the cost and benefit of blood testing.