Testosterone is a sex hormone which is found in large quantities in males and helps in maintaining bone health, sex drive and sperm production. But as men age, they experience a significant reduction in testosterone levels, which leads to the loss of body hair, muscle bulk and increase in body fat. However, this is not all that happens when testosterone levels decrease, as many studies have shown the relationship between testosterone deficiency and elevated risk of cardiovascular diseases.

In medical terms, testosterone deficiency is called Hypogonadism. It is related with reduced insulin, an increased fat mass, cholesterol and low HDL-cholesterol, elevated triglycerides and impaired glucose tolerance, all of which lead to the risks of developing cardiovascular diseases. The testosterone levels in men are at their peak in their 30s, which gradually decrease at a rate of rate of 1% to 2% annually [1].

A Massachusetts Male Aging Study (MMAS) has indicated that the incidence of hypogonadism is rapidly increasing within the aging population of the US. The study shows estimates, which indicate that around 2.4 million men, who are aged between 40 and 69, are diagnosed with hypogonadism in the United States. The study also shares that every year about 481,000 new cases of hypogonadism are reported within the same age group of American men [2].

Coronary risk factors and Testosterone

Previously, it was believed that the differences in risk factor profiles of men and women were the reason behind the higher incidence of coronary disease in men. It was believed that this was due to the behaviors of men like excessive smoking and intake of highly fat saturated diets, which made them more prone to developing these diseases. But with time, several logistic regression analysis were conducted which proved that such differences in behavioral profiles do not account for the higher risk of coronary disease in men.

Studies have also shown that the risk of developing coronary diseases is approximately three times higher in men as compared to women [3]. Also, men are prone to developing these diseases 10 years before than women. It has been found that this happens due to the low level of sex hormones (testosterones) present in men, as they play a vital role in the aetiology of cardiovascular disease.

Another well-recognized risk factor is the metabolic syndrome which leads to coronary morbidity and mortality and atherosclerosis. The syndrome has several components including hyperglycaemia, insulin resistance, dyslipidaemia, type 2 diabetes, and hypertension. These components are independently related with frank hypogonadism and hypotestosteronaemia.

Furthermore, it has been found that the absolute serum testosterone level is inversely proportional to the number of components of the metabolic syndrome, but if all of the syndrome’s components are present, then the risk of frank hypogonadism increases tenfold [4].

Testosterone Levels of Men With Coronary Heart Disease

There is a large amount of literature available which indicates that men without coronary artery disease (CAD) have higher testosterone levels than men who have been diagnosed with CAD. Several studies have been conducted that compare men with and without CAD, and most of them have concluded that men with CAD have significantly lower testosterone levels, both total and bioavailable.

However, some earlier studies suggest otherwise and there is inconsistency in the findings. Analysts say that this inconsistency in the earlier reports is because of the variability in study design, in the measures of testosterone quoted, in the definitions of ‘cardiovascular disease’ and ‘hypogonadism’ used, and in the assays applied.

Heart Failure and Testosterone

In the Western world, the leading cause of heart failure is the presence of coronary heart disease. Heart failure is mostly caused by a catabolic state which takes place due to the maladaptive neurohormonal activation, vasodilator incapacity and activation of inflammatory cytokines. It has been observed that testosterone imposes a particular type of effect due to which it resists all of these implications. In another study, it has been observed that intravenous administration of testosterone increases cardiac output in men, and hence it concludes that the levels of serum testosterone, positively correlate with heart failure and cardiac output in men.

Moreover, research has also been conducted on the effects of chronic testosterone supplementation. In a small scale clinical trial, improvements in the rate of heart failure were observed in symptom scores and exercise capacity after providing testosterone therapy to men for 12 weeks. A large scale clinical trial was conducted afterwards, in which a decline in electrocardiographic Q-T dispersion and improvements in maximal strength, insulin resistance, symptom scores, VO2 max, and exercise capacity were observed [5].

These studies showed quite positive results. However, more evidence is required to completely understand the mechanisms of testosterone which lead to heart failure. Moreover, the long-term effects of supplementation also need to be researched properly to get a clear picture.

Key Findings of Other Research Studies

From the above discussion, it can be concluded that men with hypogonadism are mostly diagnosed with coronary artery disease (CAD) and cardiovascular disease (CVD). To reinforce the conclusion on this topic, following are some of the key findings of other research studies on the same topic:

  • The low levels of testosterone have a negative impact on various cardiovascular risk factors such as endothelial dysfunction, central adiposity, dyslipidaemia, diabetes, and insulin resistance.
  • Experiments and studies on the isolated cells of animals show that those mechanisms that imitate the atherosclerotic process are readily adapted by testosterone in the body.
  • Men with mid-upper normal range of endogenous testosterone levels have less chances of having cardiovascular events and mortality than those men who have either higher range or lower range endogenous testosterone levels.
  • Men with mid-normal range levels of testosterone after going through testosterone replacement have shown improved mortality and reduction in cardiac ischaemia, functional exercise capacity and several cardiovascular risk factors.
  • In the case where patients were given a high dose of testosterone or were undertreated, have been found to be more prone to developing cardiovascular diseases.