Fertility starts in the brain with GnRH
The reproductive process for men is one of the primary functions of the endocrine system. A man’s reproductive health starts in the brain. The hypothalamus sends signals to the pituitary gland through gonadotropin-releasing hormones (GnRH). GnRH helps produce follicle stimulating hormones (FSH) and luteinizing hormones (LH). GnRH levels are low in childhood and increase during puberty. While creating incorrect levels are rare, low levels can impact sperm production and testosterone.
LH and testosterone
The anterior pituitary gland produces LH and FSH, then transfers both hormones through the bloodstream to the testes. Inside each testicle is a network of cells and capillaries that help produce sperm and testosterone. When both hormones arrive at the testes, the goal is to help get these processes going. Luteinizing hormone instructs the leydig cells to produce testosterone. So without LH, male fertility is impossible. More importantly, the testes need a precise balance of LH to avoid infertility.
Testosterone and the LH feedback loop
LH activates testosterone, an androgen present in men. Testosterone plays a role in sperm production and has other functions in male development. These functions include:
- Development of the penis and testes
- Prostate function
- Sexual libido, sexual function, and virility
- Muscle mass and bone density
- Physical changes that happen during puberty, like deepening of the voice, height, and facial hair
Testosterone levels, like LH, needs to be balanced. Too little testosterone can create hypogonadism, while too much testosterone limits LH. Both conditions send feedback to the brain to develop more or reduce LH.
FSH and sperm production
While LH and testosterone affect sperm generation, FSH is critical for the production and formation of sperm. Working together with testosterone, FSH also controls the hormone cycle or the turnover to sperm production. An FSH imbalance is a sign that can signal low testosterone and low sperm production. Low FSH can also reduce sperm quality, making pregnancy more difficult.
It’s all about balance
These 4 hormones need to work together in a healthy balance for the best fertility possible. Too much or too little of each can cause reproductive failure. A typical example of this is men who take exogenous testosterone for physical performance without medical advice. The result is often a drop in LH and FSH, leading to infertility. A hormone imbalance can show low sex drive, fatigue, weight loss, and reduced muscle mass. Most of all, men trying to get pregnant may have subfertility or infertility.
There is hope through treatment
With a clear idea of current hormone levels, an endocrinologist can provide a treatment plan. Men with hypogonadism, for instance, can benefit from testosterone replacement therapy. Medication like clomiphene citrate is often used as an off-label treatment to increase FSH and LH. Some studies show promise, but more research is needed. Lifestyle changes like decreasing smoking and alcohol, adding a healthy diet, and avoiding harsh environments can help. If these fail, techniques like IUI or IVF can increase the chances of pregnancy with a partner. Talk to a doctor if there are any concerns about these hormones and possible treatment options.
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