Background
Reliable biomarkers of androgen activity in humans are lacking. The
Conclusions
We identified potential new protein biomarkers of testosterone action. Further investigations to elucidate their clinical potential are warranted. Funding: The work was supported by ReproUnion2.0 (grant no. 20201846), which is funded by the Interreg V EU program.
Methods
Blood samples from 30 healthy GnRH antagonist treated males were collected at three time points: (1) before GnRH antagonist administration; (2) 3 weeks later, just before testosterone undecanoate injection, and (3) after additional 2 weeks. Subsequently, they were analyzed by mass spectrometry to identify potential protein biomarkers of testosterone activity. Levels of proteins most significantly associated with testosterone fluctuations were further tested in a cohort of 75 hypo- and eugonadal males suffering from infertility. Associations between levels of those markers and cardiometabolic parameters, bone mineral density as well as androgen receptor (AR) CAG repeat lengths, were explored.
Results
Using receiver operating characteristic analysis, 4-hydroxyphenylpyruvate dioxygenase (4HPPD), insulin-like growth factor-binding protein 6 (IGFBP6), and fructose-bisphosphate aldolase (ALDOB), as well as a Multi Marker Algorithm, based on levels of 4HPPD and IGFBP6, were shown to be best predictors of low (<8 nmol/l) vs normal (>12 nmol/l) testosterone. They were also more strongly associated with metabolic syndrome and diabetes than testosterone levels. Levels of ALDOB and 4HPPD also showed association with AR CAG repeat lengths. Conclusions: We identified potential new protein biomarkers of testosterone action. Further investigations to elucidate their clinical potential are warranted. Funding: The work was supported by ReproUnion2.0 (grant no. 20201846), which is funded by the Interreg V EU program.