When diagnosing a hormonal imbalance as the main reason for a man's infertility, a complete evaluation of his testosterone levels is needed. Testosterone is made primarily in the man’s testicles and a small amount in his adrenal gland. If there is a problem with the testicle, the testosterone may be low.
Many more men with infertility have low testosterone than men with normal fertility. However, the majority of men with infertility still have normal testosterone levels because the testicles can sustain testosterone production better than they can sustain sperm production when there is a problem. Luteinizing Hormone (LH) is a hormone that is produced by the pituitary gland, which stimulates the testicles to produce testosterone.
Follicle Stimulating Hormone
Follicle Stimulating Hormone (FSH) is the hormone that is produced by the pituitary gland, which stimulates the testicles to produce sperm. The pituitary gland is a grape size structure that hangs from the mid-portion of the brain in the center just behind the eyes. When the testicles receive this hormone, they make sperm which then releases a signal back to the pituitary telling it to stop releasing so much FSH. This signal is called inhibin. If there is a problem with the testicle, there won’t be normal or in some cases any sperm production and there will be less inhibin signal released and as a result, the pituitary gland will release higher than normal amounts of FSH.
Therefore, a higher than normal FSH is a signal that low or even no sperm counts are due to a problem with the testicle working as opposed to a blockage. There can, on the other hand, be a problem with a lack of stimulation. In this situation, the pituitary or the hypothalamus, which is a part of the brain above the pituitary that controls it, is not releasing adequate levels of hormones such as FSH. So the testicles are simply not getting enough stimulation to make sperm. In this case, if the pituitary can be stimulated to release more FSH or if an injection of FSH is given to the patient, the testicles will usually produce more sperm. If the FSH is already high, injecting more FSH is not likely to help. Usually in this situation, the pituitary is not releasing enough LH to stimulate adequate testosterone production from the testicles either. HCG injections can mimic LH and stimulate the testicles to produce more testosterone which also then stimulates sperm production.
A known cause of low FSH and LH production is Kallmann syndrome in which a man is born without a part of his pituitary gland. Because the part of the nose that receives the sense of smell is right underneath the pituitary, it doesn’t form in this condition and these men have no sense of smell. The treatment for these men is every other day or twice a week injections of HCG and FSH. Sperm production will improve over a time period of a few months to over a year. The sperm counts tend to remain low but the pregnancy rates are usually very good anyway. Some men have low FSH and LH but still have the ability to produce higher levels to better stimulate their sperm production. For these men, oral clomiphene citrate, also known as clomid, will trick the pituitary gland into producing more of its own FSH and LH signal. Clomid has a very low side effect profile and it can be taken over a long period of time if necessary. If a man has an elevated FSH, clomid will not help his condition since the FSH signal is already amplified and is not working because the testicle itself is abnormal and unable to respond.
Prolactin
Prolactin is a hormone which is produced at low levels by the pituitary gland. If there is a tumor of the pituitary gland, there may be an excess secretion of prolactin which will suppress the signals to the testicles to produce testosterone and sperm. A high prolactin level is an indication to look for a pituitary tumor with an MRI of the brain. Sometimes pituitary tumors do not secrete prolactin but cause the FSH and testosterone to be low. This hormonal pattern can be a tip off to check an MRI of the brain.
Estrogen
Excessive estrogen can prevent the pituitary from releasing the normal stimulation to the testicle for sperm and testosterone production. High estrogen or estradiol can be detected on blood testing. Estrogen levels may be higher in obese men, and weight loss can improve this cause of low testosterone and infertility. Medications can be used to decrease the production of estrogen that occurs in the fat of these men which usually increased testosterone levels and may improve fertility.
Testosterone is mostly produced in the testicle. The amount of testosterone in the testicle is about 100 times more concentrated than the amount in the blood stream. Only one percent of the concentration that the sperm are exposed to is flowing though the circulation to reach the pituitary gland. When the pituitary received that much lower concentration it then stops sending the signal to the testicle to make more testosterone. This signal is called Luteinizing Hormone (LH).
If a man is given testosterone, whether it's injected or through a topical gel or patch, the concentration that gets into his blood is about the same as the concentration that the pituitary is used to receiving but only one percent of that the sperm needs. Nonetheless the pituitary is tricked into stopping the signal to simulate the testicle and additionally it is tricked into stopping the signal to stimulate the sperm production. As a result, very little LH and very little FSH is released. Without normal levels of LH, very little testosterone is produced inside the testicles and sperm production which relies on FSH as well as high testicular levels of testosterone 100 times higher level of testosterone is shut down. Testosterone supplements shut down sperm production they do not improve it. Thyroid abnormalities—either too much or too little can result in impaired fertility as well and this may be screened for with blood testing.
