Testosterone is the primary male hormone responsible for regulating sex differentiation, producing male sex characteristics, spermatogenesis, and fertility (Nassar & Leslie, 2021). Testosterone generally peaks during adolescence and early adulthood. After which, levels gradually decline by approximately 1% a year after age 30 or 40 (Mayo Clinic, 2020). Some of the characteristics regulated by testosterone include male hair patterns, vocal changes/deepening, anabolic effects such as growth spurts, and skeletal muscle growth, even stimulating erythropoiesis resulting in higher hematocrit counts as compared to females (Nassar & Leslie, 2021). In puberty, the hypothalamus secretes gonadotropin releasing hormones (GnRH), which travels down the hypothalamohypophyseal portal system to the anterior pituitary, which secretes luteinizing hormones (LH) and follicle-stimulating hormones (FSH) (Nassar & Leslie, 2021). LH acts on the Leydig cells to increase testosterone production while FSH helps to control the production of sperm. Testosterone limits its secretion through a negative feedback loop which means that high levels feed back to the hypothalamus to suppress secretion of GnRH and to the anterior pituitary, to make it less responsive to the GnRH stimuli (Nassar & Leslie, 2021).
Based on Darren’s lab results, it looks like his testosterone level is lower than normal, which could potentially be due to aging, or an array of other causes to include trauma, medications, chemotherapy, and genetic disorders, among others, causing primary or secondary hypogonadism (Cleveland Clinic, 2018). Hypogonadism can be either primary, wherein there is not enough testosterone in the body as a result of a problem with the sex gland or the testicles, or secondary, wherein the problem lies with the hypothalamus or pituitary glands which are responsible for sending signals to the gonads (Nassar & Leslie, 2021). Low testosterone is manifested by decreased libido, erectile dysfunction, depressed mood, fatigue, irritability, increased body fat, muscle loss, gynecomastia, osteoporosis, as well as hot flashes, and among these, his symptoms of lack of energy, weight gain, and decreased erections are included (Cleveland Clinic, 2018). To determine the cause of hypogonadism, Nassar & Leslie (2021) mention that it is prudent for providers to not only to get a good H&P, but also to order labs such as total serum testosterone between 8AM and 10AM. They added that if levels are low, a repeat draw should be done along with FSH and LH levels. They further stated that low testosterone in the setting of normal FSH and LH indicates secondary hypogonadism, whereas low testosterone with elevated FSH and LH indicates primary hypogonadism. With secondary hypogonadism, the next steps would be to get prolactin, T4, 8AM cortisol, iron, and ferritin levels, as well to get a brain MRI to determine underlying cause. For primary hypogonadism, it is probably a good idea to order a karyotype to determine genetic cause (Nassir & Leslie, 2021).
In sorting through his current medications, the other possibility I noted that may contribute to one of his concerns is that Niacin deficiency can also cause extreme tiredness (NIH Office of Dietary Supplements, 2021), so maybe her vitamin B3 levels may need to be checked and diet reviewed to ensure she is taking enough, but if not, then maybe it is worth checking her lipid levels as well to see if uptitrating the dosage may be appropriate. On another note, antihypertensives such as thiazide diuretics have been reported to have an occasional side effect of erectile dysfunction because such medications can cause decreased blood flow to the penis. Therefore, if Darren is concerned about ED, he should bring this up to his provider to see if there is an appropriate substitute for lisinopril/HCTZ (Solan, 2017).
Testosterone replacement therapy (TRT) is used to treat low testosterone levels which can be given in several ways such as IM injections, testosterone patches, testosterone gels, and pellets (Cleveland Clinic, 2018). Based on the information provided, Darren will be a good candidate for TRT. However, it is important that even though his PSA levels are normal now, it should be monitored frequently as TRT can increase PSA levels and additionally undergo periodic prostate cancer screening to ensure that there is no other reason for the elevation of PSA (Cleveland Clinic, 2018). Those who should not take TRT are those who already have enlarged prostate causing symptoms, lump on their prostate that has not been evaluated yet, PSA level above 4, breast cancer, elevated Hct level as TRT can increase Hct levels making a person prone to thrombosis, severe CHF as TRT can cause mild fluid retention, and untreated OSA (Cleveland Clinic, 2018).
References:
Cleveland Clinic (2018). Low testosterone (male hypogonadism). Retrieved August 16, 2021 from https://my.clevelandclinic.org/health/diseases/15603-low-testosterone-male-hypogonadism
Mayo Clinic (2020). Testosterone therapy: potential benefits and risks as you age. Retrieved August 16, 2021 from https://www.mayoclinic.org/healthy-lifestyle/sexual-health/in-depth/testosterone-therapy/art-20045728
National Institutes of Health, Office of Dietary Supplements (2021). Niacin. Retrieved August 16, 2021 from https://ods.od.nih.gov/factsheets/Niacin-Consumer/
Nassar, G., & Leslie, S. (2021). Physiology, Testosterone. In: StatPearls. Treasure Island, FL.: StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526128/
Solan, M. (2017). Blood pressure drugs and ed: what you need to know. Harvard Health Publishing. Retrieved August 16, 2021 from https://www.health.harvard.edu/mens-health/blood-pressure-drugs-and-ed-what-you-need-to-know
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