Reasons for a Low FSH in Males

Follicle-stimulating hormone, or FSH, helps regulate the reproductive processes in both men and women. It affects the growth process, puberty maturation and the development of the body. FSH levels are used to help diagnose a number of factors including fertility. Low levels of FSH in men can be linked with pituitary and hypothalamic disorders.

Lowered FSH in men can be due to a number of reasons. Credit: Digital Vision./Photodisc/Getty Images


Hypogonadism is a common reason for males who show a low FSH level. Insufficient testosterone is produced resulting in underdeveloped testicles and lowered sperm count. Either the pituitary or hypothalamus gland may be at fault. There may also be a tumor present in either the pituitary or hypothalamic gland which can be identified with a radiological examination. The Geneva Foundation for Medical Education and Research states that a combination of CT scan and evaluation of prolactin serum levels can help with tumor diagnosis. If there is no tumor present, hypogonadism may be treated with testosterone replacement therapy by injection or topical application of a cream.

Kallmann Syndrome

Kallmann syndrome can be a reason for registering a low FSH level. This inherited disorder affects men more often than women. The condition includes a failure to go through puberty and may also result in a partial or complete loss of smell. Cigna Health Services states that Kallman syndrome is rare and due to a hormonal imbalance that is caused by hypothalamus failure in the brain.


Hyperprolactinemia can be a reason for low FSH levels in men and may first be preceded by symptoms such as vision difficulties and headaches. Georgia Reproductive Specialists state patients should first undergo radiology tests to rule out a tumor in the pituitary gland. The condition indicates a lowered pituitary response due to too little testosterone production. Both lowered libido and impotence are associated with the condition.

Fertile Eunuch Syndrome

Fertile eunuch syndrome, or FES, can be a reason for low FSH in men. Men with FES also tend to have low levels of luteinizing hormone which is the hormone that signals sperm production in the testicles. Even though men with FES have a low testosterone level, they are still able to produce sperm. Testosterone therapy is used to treat this condition along with human chorionic gonadotropin, or HCG, therapy, with the aim of increasing testosterone.

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