Testosterone is necessary for normal sperm development. It activates genes in Sertoli cells, which promote differentiation of spermatogonia. It regulates acute HPA (hypothalamic–pituitary–adrenal axis) response under dominance challenge.[22] Androgen including testosterone enhances muscle growth. Testosterone also regulates the population of thromboxane A2 receptors on megakaryocytes and platelets and hence platelet aggregation in humans.[23][24]
There is an increased incidence of hypogonadism in men with rheumatoid arthritis. Tengstrand et al (2002) studied hormonal levels in 104 men with rheumatoid arthritis and 99 age-matched healthy men. They divided their subjects into 3 age groups: 30–49, 40–59, 60–69. Mean non-sex hormone binding globulin-bound testosterone (bioavailable testosterone) was lower in men with rheumatoid arthritis for each of the three groups. LH was also found to be lower in the patients with rheumatoid arthritis suggesting a hypothalamic-pituitary cause of the reduced bioavailable testosterone. Of the 104 men with rheumatoid arthritis, 33 had hypogonadism compared to 7 of the 99 healthy controls.

Cardiovascular disease, and its underlying pathological process atherosclerosis, is an important cause of morbidity and mortality in the developed and developing world. Coronary heart disease in particular is the commonest cause of death worldwide (AHA 2002; MacKay and Mensah 2004). As well as increasing with age, this disease is more common in the male versus female population internationally, which has led to interest in the potential role of sex hormones in modulating risk of development of atherosclerosis. Concerns about the potential adverse effects of testosterone treatment on cardiovascular disease have previously contributed to caution in prescribing testosterone to those who have, or who are at risk of, cardiovascular disease. Contrary to fears of the potential adverse effects of testosterone on cardiovascular disease, there are over forty epidemiological studies which have examined the relationship of testosterone levels to the presence or development of coronary heart disease, and none have shown a positive correlation. Many of these studies have found the presence of coronary heart disease to be associated with low testosterone levels (Reviews: Jones, Jones et al 2003; Jones et al 2005).
Growth of spermatogenic tissue in testicles, male fertility, penis or clitoris enlargement, increased libido and frequency of erection or clitoral engorgement occurs. Growth of jaw, brow, chin, and nose and remodeling of facial bone contours, in conjunction with human growth hormone occurs.[21] Completion of bone maturation and termination of growth. This occurs indirectly via estradiol metabolites and hence more gradually in men than women. Increased muscle strength and mass, shoulders become broader and rib cage expands, deepening of voice, growth of the Adam's apple. Enlargement of sebaceous glands. This might cause acne, subcutaneous fat in face decreases. Pubic hair extends to thighs and up toward umbilicus, development of facial hair (sideburns, beard, moustache), loss of scalp hair (androgenetic alopecia), increase in chest hair, periareolar hair, perianal hair, leg hair, armpit hair.
In this study, an ethical approval No. 20171008 was obtained from Ethical Committee of Qassim province, Ministry of Health, Saudi Arabia. At the beginning, a written informed consent was taken from a 30-year-old man for participation in this study. The patient came to the King Saud Hospital, Unaizah, Qassim, Saudi Arabia, with abdominal pain. He looked pale and hazy, hence, immediately admitted. A battery of lab tests was ordered by the attending physician. Moreover, abdominal ultrasound imaging was performed. The results of the tests showed high levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), indicating liver injury. Other serum parameters, such as total proteins, albumin, and iron, in addition to the levels of kidney and heart enzymes were all found to be in the normal range. A complete blood count showed normal levels of red blood cells, white blood cells, and platelets. The ultrasound images of the man’s abdomen were all found to be normal as well [Figure 2]. The patient, a sportsman, described that he was taking a testosterone commercial booster product called the Universal Nutrition Animal Stak for the purpose of enhancing his testosterone profile to achieve a better performance and body composition. The attending physician decided to admit the man for 1 week. Some medications were prescribed, and the patient was discharged later after having fully recovered.
Some of these signs and symptoms can be caused by various underlying factors, including medication side effects, obstructive sleep apnea, thyroid problems, diabetes and depression. It's also possible that these conditions may be the cause of low testosterone levels, and treatment of these problems may cause testosterone levels to rise. A blood test is the only way to diagnose a low testosterone level.