Carbon isotope ratio of endogenous urinary steroids of the Cuban population of athletes studied for doping purposes

The aim of this work was to validate the gas chromatography/combustion/isotope ratio mass spectrometry method in Havana Antidoping Laboratory and verify its implementation with a study of the Cuban population. The method was precise and accurate inside the linear working range; the limit of quantification and the uncertainty were compliant with TD2019IRMS. The study of the Cuban population showed no differences in δ¹³C values between females and males. Only three values of Δδ¹³C showed significant differences between sexes (PD‐T, OHA‐T, and 11‐keto‐Et‐T). The values of δ¹³C between ?17.8‰ and ?21.2‰ (upper and lower limits based on normal distribution) were consistent with other populations where C4 plant derivatives prevail in the diet.