SUN-107 - Serum Androgen Profile of Athletes Entering Elite Competition

In Athletics, the binary sex classification protects female competitors against insuperable male physical advantages arising from male puberty when the sustained 20-30-fold increase in testosterone production creates larger and stronger muscles and bones, higher cardiorespiratory capacity and hemoglobin. Unlike other acceptable genetic advantages for sports as features of athlete’s natural talents, genetic mutations causing XY Disorders of Sex Development (DSD) defeat the binary sex classification if male-bodied athletes compete in elite female events. The most frequent XY DSDs are complete androgen insensitivity syndrome [CAIS; eligible to compete in the female category] and 5α-reductase type 2 deficiency [5ARD; androgen sensitive and ineligible] but their hormonal features among elite athletes are not well described.

Aims: To define serum androgen profiles of individuals participating in elite Track and Field events

Methods: Athletes in elite events (n=1689; male 889, female 800) provided anti-doping serum samples (n=5516, median 3 per person; April 2023 to August 2025 prior to new SRY eligibility regulation) for analysis by liquid chromatography mass spectrometry (LCMS) in 19 WADA-accredited antidoping laboratories, for their serum androgen profile (testosterone [T], dihydrotestosterone [DHT], androstenedione [A4]). Steroid concentrations and ratios in coded samples were analysed by linear mixed model for repeated measures with Bonferroni adjustment for multiple comparisons and data imputation for left-censored (DHT) data.

Results: Athletes were classified into male, female and XY DSD categories (based on clinical diagnosis of 5ARD, CAIS or as unclassified (UNCL] if diagnosis was unknown). The prevalence of 5ARD among XY DSDs was 6.1 [1.5-23.7] times that of CAIS (p < 0.003, Fisher’s test). After excluding samples from pregnant athletes (n= 15) or antidoping rule violations (n=28, from urine samples) the following data were observed with m and f indicating significant difference from male and female, respectively. Data were specified as number of samples (n) and mean ± SEM.
Serum T (nM): men (n=2682, 19.7 ± 0.15)f, women (2820, 1.1 ± 0.02) m, 5ARD (25, 21.6 ± 2.1)f, CAIS (15, 46.3 ± 3.9) f,m and UNCL (16, 17.1 ± 3.3)f
Serum T/DHT ratio: men (n=1903, 14.4 ± 0.3)f, women (1824, 3.9 ± 0.1)m, 5ARD (16, 30.7 ± 4.5) f,m, CAIS (14, 22.6±0.9) f,m and UNCL (13, 36.8±6.9) f,m
Serum T/A4 ratio: men (n=2586, 10.2 ± 0.1)f, women (2666, 0.34±0.0)m, 5ARD (19, 7.6±0.8) f,m, CAIS (14, 12.4±0.6)f,m and UNCL (15, 6.1±1.0) f,m

Conclusions: Most XY DSD individuals entering in elite female Athletic events have 5ARD and are androgen sensitive. Using LCMS measurements (a) CAIS have the highest serum T concentrations, (b) 5ARD and UNCL have similar T/DHT ratio and serum T concentrations to males, (c) serum T/DHT ratio (by LCMS) to characterize 5ARD can be extended from sedentary individuals to elite athletes.

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