Obtaining Testosterone and FSH levels are minimum baseline hormones needed to assess fertility status affording the ability to differentiate between subtypes of subfertility or infertility.  

The hypothalamic-pituitary-gonadal (HPG) axis drives male sexual development and fertility.  GnRH is secreted by the hypothalamus in a pulsatile manner.  It is the distinct frequency and amplitude of these pulses that directly drive LH and FSH secretion from the anterior pituitary. 

FSH 

LH

Testosterone

Inhibin

Estrogen

PDF icon References Assessing Testicular Reserve.pdf