Normal sperm production and sexual function are dependent on normal hormonal balance. Measuring blood levels of FSH, LH, testosterone and prolactin may be carried out in some men to identify further information.

For example the measurement of FSH and LH can help identify the underlying cause of azoospermia. Those patients who have azoospermia due to an obstruction in the vas deferens have normal FSH levels, whereas those patients who are not making sperm have raised FSL levels. Low levels of FSH and LH may indicate that the pituitary gland is not producing enough hormones.Besides this, an over-production of the hormone prolactin, or a deficient thyroid gland can disrupt the hormone balance and thereby have an effect on fertility. However, hormonal causes of male fertility problems rarely occur.