Probably so, medical experts say. But whether that means athletes like her should be barred from competitions is a fraught question.
The Court of Arbitration for Sport in Zurich has ruled that women with very high testosterone levels — far above the normal range — cannot compete against other women in races from 400 meters to one mile unless they take drugs to suppress production of the hormone.
The ruling prevents Caster Semenya, 28, an elite runner and Olympic champion from South Africa, from competing in those races because her testosterone levels are naturally very high. She had challenged attempts to disqualify her from racing as a woman.
The science underpinning that decision is complicated, raising difficult questions about biology, fairness and gender identity.
It’s a hormone, an androgen, that has a variety of effects on the body. Women and men produce testosterone, but women don’t make nearly as much.
In men, high levels of testosterone are made by the testes. Much lower levels are produced in the adrenal glands, which rest above the kidneys.
Women also make testosterone in their adrenal glands, and in their ovaries. But testes produce much more: Testosterone levels in men are 295 to 1,150 nanograms per deciliter of blood, while the levels in the women are 12 to 61 nanograms per deciliter of blood.
Testosterone “builds muscle,” said Dr. Benjamin D. Levine, who studies sex differences in athletic performance at the University of Texas Southwestern Medical Center. “It builds skeletal muscle, it builds cardiac muscle. It increases the number of red blood cells.”
The effects are seen whether the hormone is naturally present or introduced with drugs. In one of the most infamous examples, women who represented East Germany at the Olympic Games in the ’70s and ’80s achieved astounding success after they were unknowingly doped with anabolic steroids including testosterone.
