Introduction
Sex differences play a role in the risk of cardiovascular diseases. This is due to the differences in sex hormones between men and women. Testosterone concentrations have an impact on cardiovascular diseases. Low testosterone concentrations result in adverse cardiovascular effects such as inflammation, dyslipidemia, insulin resistance, and atherosclerosis. So, a low testosterone level acts as a cardiovascular risk factor. This article gives insight into the potential and harmful effects of testosterone concentrations on the cardiovascular system.
What Is Testosterone?
Testosterone is a male sex hormone produced by the testes and is transported in the blood. However, only one to two percent of testosterone circulates as free testosterone and exhibits biological activity. This hormone is responsible for the development of primary and secondary sex characteristics. The testosterone hormone is associated with sex drive in men. It also plays a role in increasing muscle mass and bone density. The testosterone hormone levels in men begin to decrease at the age of 40, and this decrease in the testosterone level has been associated with an increase in cardiovascular risk.
What Are the Cardiovascular Effects of Testosterone?
Testosterone has various effects on the blood vessels of the cardiovascular system. It protects cardiac health and the vessels of the heart and decreases the risk of cardiac diseases. Testosterone dilates the arteries, including the coronary arteries of the heart and the aorta, to lower blood pressure. It reduces the risk of atherosclerosis by preventing the accumulation of lipids and fats on the walls of the arteries. It acts as a vasodilator and an endothelium-repairing hormone.
It decreases the production of inflammatory cytokines such as interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha, which are responsible for atherosclerotic events. Testosterone induces vasodilation, reduces the heart rate, improves glycemic control, and has prothrombotic and anti-obesity effects. The decrease in testosterone concentrations is associated with cardiac failure and progressing side effects of heart failure, such as a decrease in muscle mass, decreased exercise ability, fatigue, dyspnea (shortness of breath), and cachexia (muscle wasting disease).
What Happens in Testosterone Deficiency?
Testosterone deficiency is associated with medical conditions such as diabetes, metabolic syndrome, hypertension, dyslipidemia, frailty, renal failure, malignancy, and cardiovascular diseases. This deficiency increases the risk of cardiovascular disease and mortality. Testosterone has vasodilatory action and affects myocardial oxygen consumption and membrane repolarization. Hence, its deficiency causes coronary artery disease. It is also associated with congestive heart failure, dyslipidemia, and metabolic syndrome.
What Are the Effects of Testosterone on Cardiovascular Diseases?
Testosterone has various effects on cardiovascular physiology. It has direct effects on the blood vessels of the cardiovascular system and the heart. It slows the development of atheroma and reverses the deposition of lipids in the artery wall. It has beneficial effects on carotid intima-media thickness and plaque calcification. Testosterone has prothrombotic effects, which increase the risk of myocardial infarction and stroke following a plaque rupture.
Testosterone has beneficial effects on glycemic control by improving insulin sensitivity through non-genomic activation of insulin receptor signaling factors. It is also associated with obesity, in which testosterone reduces abdominal fat through the induction of lipolysis and inhibition of adipogenesis. Testosterone also has anti-inflammatory effects. Inflammation is a major risk factor for cardiovascular diseases and atherosclerosis. Testosterone exhibits an anti-inflammatory effect by suppressing the proinflammatory cytokines and enhancing the anti-inflammatory cytokines.
What Is Testosterone Replacement Therapy?
Testosterone replacement therapy is performed to normalize low levels of testosterone. It is usually performed in patients with hypogonadism, in which testosterone deficiency is present. Research studies are being performed for the administration of testosterone in patients with cardiovascular conditions such as myocardial ischemia, coronary atherosclerosis, heart failure, and cardiac electrophysiology.
What Are the Effects of Testosterone Replacement Therapy?
The effects of testosterone replacement therapy include the following:
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Testosterone therapy reduces low-density lipids (LDL) and total cholesterol concentrations. However, high doses can derange the lipid profile. Triglyceride levels are not affected by testosterone therapy.
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Testosterone therapy improves insulin resistance and glycemic control in diabetic patients.
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Testosterone treatment has favorable effects on coronary and peripheral vasomotion and stiffness of the peripheral arteries. Intracoronary testosterone exerts physiological effects such as epicardial coronary artery dilatation and an increase in the blood flow in coronary artery disease. It also improves myocardial perfusion in areas supplied by unobstructed coronary arteries but not in arteries with significant atherosclerosis.
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A single dose of testosterone improved the cardiac output and reduced systemic vascular resistance, with the effects coinciding with maximal testosterone concentrations. It also has beneficial effects on exercise capacity and oxygen consumption.
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A decrease in testosterone levels increases the risk of cardiovascular diseases. It is shown that testosterone therapy reduces the risk of cardiovascular diseases, including myocardial infarction and stroke. However, the benefit is weighed against the replacement of testosterone.
What Are the Risks Factors Associated With Testosterone Replacement Therapy?
Testosterone therapy also causes various adverse effects. It can cause erythrocytosis, benign prostatic hyperplasia, fluid retention, hepatotoxic and neoplastic effects, gynecomastia, acne, and skin reactions. It also increases the hematocrit and hemoglobin levels and has detrimental effects on lipids. Testosterone therapy is not recommended in patients with prostate cancer, suspected or increased risk of prostate cancer, low levels of hematocrit values, and uncontrolled heart failure. The current guidelines have recommended avoiding testosterone therapy in patients with a recent myocardial infarction, advanced or severe cardiac failure, revascularization, and stroke within the last six months. However, some studies suggest that endogenous testosterone has a significant role in the formation of blood clots and heart failure. Studies are being performed to identify the positive and detrimental effects of testosterone on cardiac health.
Conclusion
Testosterone is a male sex hormone that is produced by the testes and is transported in the blood. This hormone is responsible for the development of primary and secondary sex characteristics. It also protects cardiac health and heart vessels and decreases the risk of cardiac diseases. So, physiological testosterone is essential for various functions. As this hormone decreases with age, testosterone replacement therapy is recommended for men with pre-existing cardiac diseases that have been related to an increased risk of myocardial infarction. However, extensive research is required to determine testosterone replacement therapy's harmful and beneficial effects in men.
