Changes in blood parameters after intramuscular testosterone ester injections - Implications for anti-doping

Area of Science:

• Sports Science
• Anti-Doping Research
• Endocrinology

Background:

• The Athlete Biological Passport (ABP) monitors haematological and steroidal biomarkers to detect doping.
• Testosterone administration affects red blood cell production and iron metabolism, potentially altering ABP profiles.
• Current ABP methods may require enhanced strategies to reliably detect testosterone doping.

Purpose of the Study:

• To evaluate the efficacy of the ABP's haematological module in detecting testosterone ester misuse.
• To identify specific haematological markers that indicate testosterone doping.
• To assess the complementary role of haematological and steroidal data in anti-doping efforts.

Main Methods:

• A randomized, double-blind, placebo-controlled study involving 19 eugonadal men.
• Administration of Sustanon® (testosterone esters) or placebo via intramuscular injection.
• Collection of urine and blood samples at multiple time points for steroidal and haematological analysis.
• Assessment of ABP biomarkers, including reticulocyte percentage (RET%) and steroidal profiles.
• Isotope-ratio mass spectrometry (IRMS) analysis for testosterone and metabolite detection.

Main Results:

• The steroidal profile was flagged in all testosterone-treated subjects.
• The haematological profile was flagged in six out of nine subjects treated with testosterone.
• Reticulocyte percentage (RET%) demonstrated the highest sensitivity and specificity for detecting testosterone misuse among haematological markers.
• Suspicious samples were identified 3-10 days post-injection, correlating with RET% fluctuations.

Conclusions:

• Unexpected changes in reticulocyte percentage (RET%) can serve as a key indicator of testosterone doping.
• Integrating the haematological and steroidal modules of the ABP improves the detection of testosterone misuse.
• Targeted follow-up testing using both ABP modules is recommended for substantiating testosterone doping allegations.