Do you mean World Athletics's current rules for DSD athletes seeking to compete in the female category? If so, the level of T you're citing is twice the level now allowed.
World Athletics' upper limit for XY DSD athletes with testes competing in women's events isn't 5 nmol/L like you keep saying. The current limit is under 2.5 nmol/ like I said.
The limit has been under 2.5 nmol/L since new rules went into effect at the end of March 2023.
From the document titled, "World Athletics Eligibility Regulations for the Female Classification (Athletes with Differences in Sex Development) (Version 3.0, approved by Council on 23 March 2023, and coming into effect on 31 March 2023)":
A "Relevant Athlete" is an Athlete who meets each of the following three criteria:
1) They have one of the following DSDs: 5α-reductase type 2 deficiency; partial androgen insensitivity syndrome (aka PAIS); 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) deficiency;ovotesticular DSD; or any other genetic disorder involving disordered gonadal steroidogenesis;
and
2) as a result, they have a concentration of testosterone of 2.5 nmol/L or more in their serum;
and
3) they have sufficient androgen sensitivity for that testosterone to have a material androgenising effect.
To be eligible to compete in the female classification at a World Rankings Competition, and/or to have recognised any World Record performance in a competition that is not a World Rankings Competition, a Relevant Athlete must meet each of the following conditions (the "DSD Eligibility Conditions"):
- they must be recognised at law (for example, in a birth certificate or passport) either as female or as intersex;
- they must have continuously maintained the concentration of testosterone in their serum below 2.5 nmol/L for a period of at least 24 months;
and
- they must continue to maintain the concentration of testosterone in their serum below 2.5 nmol/L at all times (i.e., whether they are in competition or out of competition) for so long as they wish to retain eligibility to compete in the female classification at World Rankings Competitions and/or to have recognised any World Record performance in the female classification at a competition that is not a World Rankings Competition.