Hypogonadism is a condition in which the testicles are not working the way they should.
In an adult, the testicles have two main functions: to make testosterone (the male hormone) and sperm. These activities are controlled by a part of the brain called the pituitary. The pituitary sends signals (called gonadotropins) to the testicles that, under normal conditions, cause the testicles to produce sperm and testosterone.
The pituitary signals can change based on the feedback signals that the brain receives from the testicle. Hypogonadism can therefore be divided into two main categories: 1) a problem with the signals from the brain to the testicles, or; 2) a problem within the testicle itself. These categories are important because they may influence the way that hypogonadism is treated, and play a role in the results.
Testicular failure (primary hypogonadism)
Testicular failure occurs when the brain is signaling the testicle to make testosterone and sperm, but the testicles are not responding correctly. As a result, the brain increases the amount of the gonadotropins signals, which causes a higher-than-normal level of these signals in the blood. For this reason, this condition is also referred to as hypergonadotropic hypogonadism.
This is the most common category of hypogonadism. Causes of primary hypogonadism include:
- congenital (the person is born with the condition): certain conditions, including Klinefelter’s syndrome, cryptorchidism, varicocele, and Myotonic Dystrophy; mutation in the FSH/LH receptor genes; chromosomal abnormalities (46, XX Male syndrome, 47, XYY syndrome, Noonan Syndrome, Y-Linked microdeletions)
- acquired: infections; radiation; environmental toxins; alkylating agents; ketoconazole; glucocorticoids; testosterone and/or anabolic steroid abuse; testicular torsion (twisting of the spermatic cord inside the testicle); autoimmune damage; chronic systemic illness
- idiopathic: the exact cause is not known.
Secondary hypogonadism (also called hypogonadotropic hypogonadism) occurs when the brain fails to signal the testicles properly. In men who have secondary hypogonadism, the testosterone levels may be very low, and sperm are usually missing from the semen. Some boys are born with this condition. In most cases, it is discovered when a boy fails to go through puberty.
Causes of secondary hypogonadism include:
- congenital (the person is born with the condition): certain conditions, including Kallman’s syndrome, Prader Willi syndrome; idiopathic (cause unknown)
- acquired: hyperprolactinemia; diabetes mellitus; obesity; steroid treatment; critical illness; chronic opiate use; anorexia nervosa; idiopathic (cause unknown)
- damage to pituitary: benign (non-cancerous) tumors and cysts; malignancy (cancer); infections; trauma (including surgery in certain areas of the brain); radiation; pituitary bleeding
What are the symptoms of hypogonadism?
Low testosterone: Hypogonadism may be diagnosed when a man has symptoms of low testosterone, including low energy, fatigue, and a lower sexual drive.
Patients with secondary hypogonadism are usually diagnosed during their teen years because they have not started puberty. These patients may not develop the body type, muscle build, or hair pattern seen in adult males. Some men will also have a poor sense of smell.
Infertility: Hypogonadism may be diagnosed when a man has a problem with fertility (cannot father a child) and is found to have no sperm or only a very low number of sperm in the semen.
How is hypogonadism treated?
Hypogonadism can be treated by giving the patient testosterone, or by increasing the signals from the brain that cause the testicle to produce testosterone and sperm. The best treatment for hypogonadism depends upon the type of hypogonadism and the patient’s goals.
Testosterone replacement: The symptoms of low testosterone can be treated with testosterone replacement.
There are many factors a man needs to consider before starting replacement testosterone therapy. Not all men with low testosterone will have symptoms that are severe enough to need medication.
Like any medication, testosterone replacement has side effects. The most important side effect is that testosterone replacement causes a decrease in sperm production in most men. Age is an important consideration; testosterone naturally declines as men age, and we don’t yet know what a “normal” testosterone level for older men is.
Fertility: Some men who have hypogonadism will want to father children. In patients with secondary hypogonadism, the testicle can usually be stimulated to make testosterone and sperm by injecting drugs that imitate the gonadotropin signals from the brain. Because it takes almost three months for mature sperm to reach the semen, men will need to continue these drugs for many months in order to have the best chance at fertility. In many cases, men will be able to cause a pregnancy on their own once their sperm production has increased.
Drugs to increase testicular function do not work in men with testicular failure. Men with testicular failure and low sperm numbers may still be able to cause a pregnancy on their own, or may need to consider assisted reproductive techniques such as intrauterine insemination or in vitro fertilization .
A biopsy (a small sample) of the testicle to retrieve sperm may be recommended in some men with hypogonadism. When sperm are found, they can be used to create a pregnancy using a technique called intercytoplasmic sperm injection.
Sabanegh Jr, Edmund, and Agarwal, Ashok. "Male Infertility." Campbell-Walsh Urology. 10th ed. Philadelphia, PA: Saunders Elsevier, 2012. 616-47. Print.
Snyder, Peter J. "Causes of Primary Hypogonadism in Males." UpToDate. Wolters Kluwer Health, 1 Aug. 2012. Web. 27 Feb. 2013.
Snyder, Peter J. "Causes of Secondary Hypogonadism in Males." UpToDate. Wolters Kluwer Health, 29 Aug. 2012. Web. 27 Feb. 2013.
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