Specific types of bodily trauma, such as testicular trauma and head/neck/spinal cord trauma can cause a significant decline in testosterone secretion and in overall testosterone levels.  This injury-related reduction in testosterone has been witnessed both clinically in well developed research studies, and within real-world patients.  This article will outline and explain many of the facts regarding hypogonadism (low testosterone) as a result of blunt bodily trauma, as well as explore some related topics.

Low Testosterone Caused By Testicular Trauma

Although well placed within the center of the body, the testes are located in the scrotum, which hangs outside of the body.  This means that unlike other important organs, testicles do not have the protection of muscles and bones.  Such exposure makes it easier for them to be struck (hit, kicked, or crushed), which often occurs during contact sports.  In most cases, the testes (made of a spongy material) can absorb the shock of an injury without serious damage.  However, due to the many nerves running throughout this region, trauma to the testes can cause extreme pain that is generally accompanied by bruising and/or swelling.

Several types of trauma to the testes can disrupt the delicate system comprised of the hypothalamus, pituitary gland, and testicles, appropriately named the hypothalamic–pituitary–testicular axis, or HPTA which produces and monitors the body’s level of testosterone (among other things).  When testicular trauma occurs, the last part of this axis malfunctions, thereby disrupting testosterone production.  Such malfunctions generally involve the following conditions:

• Testicular rupture is a rare type of testicular trauma that occurs when the testicles are squeezed against the hard surface of the pelvic girdle, or when they receive a direct blow which causes blood to leak into the scrotum.  Severe cases of testicular rupture require a surgical repair of the rupture in order to save the testicle.
• Testicular torsion is when a structure called the spermatic cord, that secures the testicle at one end gets twisted, thereby cutting off the blood flow and nourishment to the testicle.  Symptoms of testicular torsion include sudden and severe pain, swelling, tenderness, and enlargement of the affected testicle. This emergency surgery requiring disorder occurs most often in young males between the ages of 12 and 18, and can result from strenuous activity or from no apparent cause.
• Testicular cancer is a very specific form of cancer in which abnormal testicle cells develop, divide, and grow at an uncontrolled rate.  The symptoms of testicular cancer include a pulling sensation or the feeling of unusual heaviness in the scrotum; the development of a lump, or an increase in the size of one or both testicles; often transient (may come and go) pain or discomfort in a testicle or the scrotum; or an ache in the lower abdomen or groin area.
• Epididymitis, or inflammation of the epidiymis – the coiled tube that lies on and behind each testicle, and connects the testicles with the vas deferens (the tubes that carry sperm).  The epidiymis serves in the transport, storage, and maturation of sperm cells produced in the testicles, and epididymitis is typically caused by an infection or by the sexually transmitted disease chlamydia.  Symptoms of this condition include scrotal swelling and pain. 

Low Testosterone Caused By Head and Spinal Cord Trauma

Two parts of the hypothalamic–pituitary–testicular axis, the hypothalamus and the pituitary gland are in the head, which makes trauma to the head (accidents and injuries), as well as disruptions in blood flow poses potential threats to HPTA.  Neurons carry messages between the pituitary gland and the hypothalamus to signal the production of hormones.  Both structures are located at the base of the brain, and are connected by a bunch of neurons called the infundibulum.  Working together, these two sections of the brain effectively regulate all the hormones which circulate throughout the bloodstream, controlling functions as varied as statural growth (the natural height in an upright position) and hair pigmentation.

The hypothalamus is the part of the brain that lies below the thalamus, forming the major portion of the ventral region of the diencephalon, and which produces hormones that control a variety of autonomic (automatic) activities within the body among which are:

• Certain metabolic processes
• Body temperature
• Hunger
• Moods
• Specific glands, includes the pituitary gland
• Sex drive
• Sleep
• Thirst 

The pituitary gland (part of the endocrine system) regulates hormones, i.e., chemical messengers that control the functions of many of the other glands.  Since it is so central, it is often referred to as the body’s master gland.  Within the pituitary gland’s control are several homeostatic (brain preferred set points such as heart rate, respiration, adrenal gland secretion rates, etc.) and specialized functions, such as bone growth.  The pituitary gland also controls the activity of the ovaries, testes, and thyroid.

Thus, if the brain is injured by a head trauma, heart attack, or stroke, the hypothalamus and pituitary glands may be damaged, causing a significant drop in testosterone. There are numerous studies that conclusively prove the correlation (direct link) between head trauma and low testosterone, but only a couple studies (one brain injury, and one spinal cord injury) are summarized here for validity purposes.

In September of 2013 ER Rosario, et al of Casa Colina Hospital for Rehabilitative Medicine, Pomona, California published a study in the Journal of Head Trauma Rehabilitation entitled, ‘Hypothalamic-pituitary dysfunction following traumatic brain injury affects functional improvement during acute inpatient rehabilitation’.  The objective of this study was to evaluate the occurrence of hypothalamic-pituitary dysfunction following a traumatic brain injury, and to determine its effect on functional improvement in acute inpatient rehabilitation.  However, among their analysis these researchers added an additional measure, that of hypogonadism.  Specifically, ER Rosario, et al found that following traumatic brain injury, 70% of men were identified as having hypothalamic-pituitary dysfunction, while 66% were observed to be hypogonadic, along with 46% who possessed low levels of free T4, and 26% with low levels of insulin growth factor-1.  This study demonstrated a significant correlation (relationship) between its intended hypothalamic-pituitary dysfunction and low testosterone levels in men who have experienced traumatic brain injuries.

TS Huang, et al of the Department of Internal Medicine, National Taiwan University Hospital, Republic of China published an April 1993 study in the Journal of Metabolism entitled, ‘Pituitary-testicular and pituitary-thyroid axes in spinal cord-injured males’.  TS Huang, et al studied, for evaluation, the pituitary-testicular and pituitary-thyroid axes of thirty spinal cord-injured (SCI) males whose hypothalamuses and pituitary glands could no longer deliver efficient messages to the testes.  Using combined thyrotropin-releasing hormone (TRH) and luteinizing hormone-releasing hormone (LHRH) tests, in conjunction with electroejaculated semen analyses these researchers were able to compare the experimental group’s results to those of thirty age-matched normal male volunteers who represented the control group.  Their findings included several skewed and underperforming hormonal secretion levels including:  11 subjects with elevated serum prolactin levels; eight subjects with elevated serum testosterone levels; four subjects with low serum triiodothyronine (T3) levels; and one subject with elevated serum follicle-stimulating hormone (FSH) level.  Compared to the control/normal group, there were significantly elevated luteinizing hormone (LH) responses to LHRH in spinal cord-injured subjects, exaggerated and/or prolonged LH responses, elevated FSH responses, and several subjects with exaggerated thyrotropin (TSH) and prolactin responses to TRH levels.  These abnormal hormones resulted in a variety of primary and secondary problems among which were impaired sperm motility (observed in 56 electroejaculated semen samples from 16 SCI subjects), and a significant correlation between LH and diminished total sperm count.  These findings conclusively demonstrated spinal cord injury’s direct correlation to low testosterone production, low testosterone levels, and ultimately the aforementioned resulting hypogonadic symptoms. 

Resolving Secondary Hypogonadism with Infertility

Generally speaking secondary hypogonadism (also known as hypogonadotropic hypogonadism or gonadotropin deficiency) simultaneously causes both low testosterone levels, and the more difficult to treat low testosterone with infertility (diminished semen production, reduced sperm count, and poor sperm motility more clearly known as mobility) condition.

According to the Mayo Clinic, treating male hypogonadism involves replacing the male hormones synthetically, i.e., testosterone replacement therapy which is typically provided via testosterone preparation injections, gels, or patches.  According to the National Institute of Health, physicians treating secondary hypogonadism in females often prescribe estrogen or progesterone pills.  However, if the problem is determined to be specifically caused by the hypothalamus, physicians sometimes prescribe pills containing the gonadotropin-releasing hormone.

Frankly, the most important predictor of treatment success occurs prior to determining the appropriate course of action.  The physician must first accurately diagnose the problem, and identify the source of the condition.  A good endocrinologist will be able to recognize when to use a specific medical therapy to stimulate spermatogenesis, and when to refer the patient out for assisted reproductive technology.  Gonadotropin injections are often used to stimulate the sperm production, and are also a good way to improve sperm count when low testosterone is the problem.  Another valid and effective option for patients who have experienced head trauma and fear that they may have low testosterone, or have been clinically diagnosed is Human Chorionic Gonadotropin (HCG) therapy.  HCG injections mimic the release of LH, thereby stimulating natural testosterone production.

Usually, when infertility is presents, it is standard practice to first check sperm count, and if determined to be low it must be accurately measured to determine how low it is in relation to testosterone levels.  When considering these measures together, a ratio is provided, monitored, and adjusted as necessary (during treatment) to effectively resolve the problem of secondary hypogonadism.

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