Effect of Finasteride, a 5 Alpha-Reductase Inhibitor, on Serum Gonadotropins in Normal Men
 August 1992   
in “
 The Journal of Clinical Endocrinology and Metabolism 
”
 
     
   TLDR  Finasteride doesn't affect hormone levels in normal men.   
  The study investigated the effect of finasteride, a 5 alpha-reductase inhibitor, on serum gonadotropins in normal men. The results showed that finasteride did not significantly affect serum LH or FSH concentrations, indicating that it does not interfere with the hypothalamic-pituitary-testicular axis in normal men.