Quantities of both hormones are measured in a unit called a mole. Before starting therapy, Petrillo would have had about 20 nanomoles of testosterone in a litre of her blood (20 billionths of a mole). Since 2015, the International Olympic Committee (IOC) has required female athletes to have less than five nanomoles of testosterone per litre of blood, while most women have fewer than two nanomoles per litre. Petrillo is now consistently well below the two-nanomoles-per-litre level.