A man's testicles serve as reproductive organs by producing sperm. They also produce testosterone--...
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A man's testicles serve as reproductive organs by producing sperm. They also produce testosterone--the principal male sex hormone. Production of testosterone begins in a part of the brain called the hypothalamus. It produces a hormone called GnRH, which causes another part of the brain, the pituitary gland, to make two additional hormones. These two hormones travel through the bloodstream to the testicles. One called FSH triggers sperm production. The other called LH triggers production of testosterone by cells of the testes. Many men have testosterone deficiency. It can be primary - meaning the testes fail to respond to the brain hormones. Since testosterone levels remain low, the brain keeps producing FSH and LH, and blood levels of these hormones are high. It can also be secondary, meaning the hypothalamus or pituitary doesn't produce enough FSH or LH. So testosterone levels are low, while levels of FSH and LH are low or mistakenly normal. Effects can include reduced energy, mood changes, reduced muscle mass, low sex drive, and erectile dysfunction. There are many possible causes of low testosterone, which is diagnosed with a blood test. Treatment depends on the cause. Options include testosterone replacement therapy via injection, a testosterone patch, and testosterone gel.

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