Cryptozoospermia is a sperm count of less than 100,000 in the ejaculate. The cause of cryptozoospermia can be obstructive or secretory. Therefore, an analysis of the hormones FSH and Inhibin B could identify the type of cryptozoospermia, as FSH is produced at the pituitary level, while Inhibin B is produced at the testicular level.
Both hormones are involved in sperm formation, but at different levels. For example, if FSH levels are high and Inhibin B levels are low, spermatogenesis will be impaired at the testicular level. In this case, cryptozoospermia would be secretory.
However, if FSH and Inhibin B levels are normal, sperm production is not impaired. In this situations, cryptozoospermia is obstructive.