Testosterone is a hormone well known for its role in libido and sexual function, but the effects reach further. It is also essential for maintaining bone and muscle mass, the growth and healing of cells, and nervous system maintenance of opioid receptors, and dopamine and norepinephrine activity.
These functions are key to the body’s management of pain. In result, when testosterone levels are low, chronic pain is often present. In this article we will examine the actions of testosterone in relation to the management of pain and lay out guidelines to test hormone levels and treat deficiencies.
Why is Testosterone Necessary
Testosterone is important in both males and females, although it is commonly believed to be more important in males. It has the following equally critical functions in the body of both genders:
- Pain control via its involvement in opioid activity.
- It facilitates the binding of opioid receptors.
- Maintains the barrier between blood and the brain.
- Transports and activates norepinephrine and dopamine.
- It assists in healing tissues.
- Helps maintain muscle, creates a tolerance to exercise, and prevent osteoporosis.
As you can see testosterone plays important roles throughout the body. When levels are low, symptoms may include:
- chronic pain
- low energy
- lack of motivation
- easily fractured bones
- increased inflammation
- impaired healing of pain
Testosterone is necessary for libido in females too, not only men. Females however, carry a lower serum concentration of the hormone.
Physiologic Production of Testosterone
The gonadotropin releasing hormone (GnRH) is produced by the hypothalamus. This is what causes the production of follicle stimulating hormone (FSH) and luteinizing hormone (LH) by the pituitary. These two hormones further assist in the testosterone production by the gonads and the adrenal. Testosterone was thought to be produced in the testicles exclusively. However, it can be produced in the ovary and the adrenal too.
In peripheral tissue, testosterone converts into dihydrotestosterone and estradiol. Estrogens have an effect on depression and bone formation in result of the activity they cause in the central nervous system (CNS). Chronic pain has been found to use neuroplasticity to cause anatomical changes to the CNS. In order to treat deficiencies of testosterone, hormonal therapy is emerging to treat the CNS changes caused by chronic pain.
Mechanism of Testosterone Depletion
Two reasons can cause testosterone depletion. The first includes severe pain causing a pituitary insufficiency. In this case, stress is exerted on the hypothalamus and the pituitary over time, and this will cause the gonads and adrenals to produce less testosterone. Other hormones like the thyroid, cortisol, and pregnenolone, can show serum deficiencies as well.
Opioid administration is not only the second, but also the most common cause of testosterone deficiency. Intrathecal and oral opioids can allow testosterone deficiency to be observed. Opioid suppression of the GnRH in the hypothalamus can cause low testosterone serum levels. Testosterone production in the gonads or in the adrenal can be impaired by opioids. Testosterone replacement is required by both the cases, and it is not known whether the suppression of testosterone is dose-related, opioid specific, or if it has a relation to the opioid serum levels.
Testing for Testosterone Deficiency
When it comes to analyzing testosterone levels, a morning serum testosterone level should be ordered, which reports the patient’s level and what the normal range should be. Laboratories may, however, not have the same units of measure. The fraction responsible for libido and sexual function is the free bioavailable or the unbound component found in the otherwise protein bound and unbound components.
The total serum testosterone levels may present a more critical reason for the pain management because the protein bound testosterone may need to enter the body compartments, such as the CNS, pain site or the spinal cord in order for it to perform any of its functions. The pain practitioners should take into consideration the low total serum testosterone or the free unbound testosterone levels in order to get to define a deficiency that will require a replacement. Patients who are on opioid treatment and complain of weakness, lack of libido, and lethargy, should be tested for a deficiency.