Serum free testosterone level in coronary artery disease in candidates for coronary artery bypass graft surgery: A cross-sectional study

Abstract Background Due to the controversy over the effect of serum testosterone levels on coronary artery diseases, this survey explores the serum levels of free testosterone, luteinizing hormone, and follicle-stimulating hormone in candidates for coronary artery bypass graft compared with an age-matched control group and evaluates the associated factors in these participants. Objective To determine the testosterone level in elective coronary artery bypass grafting participants. Materials and Methods In this cross-sectional study, all male patients aged > 40 yr as candidates for elective coronary artery bypass grafting, who were referred to the Afshar Hospital, Yazd, Iran, from March 2018 to March 2019, were included. In total, 100 men were enrolled (50 cases and 50 controls). Their serum levels of free and total testosterone, luteinizing hormone, and follicle-stimulating hormone were measured and the results were compared. Results The findings indicated a significant difference between the two groups in total and free testosterone (both p < 0.001); they were lower in the case group. There was also a significant difference in the total testosterone of the participants with diabetes mellitus compared with no-diabetic individuals (p = 0.007). Free testosterone of diabetic subjects taking insulin was lower compared with those taking no insulin (p = 0.04). There was also an association between the body mass index and free testosterone, left ventricular ejection fraction and total testosterone, and a significant and negative relation between the duration of hospital admissions and free testosterone (p < 0.05). Conclusion This study illustrates that participants with coronary artery disease bear a significantly low testosterone level in comparison with the healthy control group.


Introduction
Over the past decades, the pattern of the most common fatal diseases in adults has changed from communicable to non-communicable diseases, of which cardiovascular diseases (CVDs) appear to be highly important with regard to global mortality as well as disease burden (1). As estimated, in 2016, about 40.5 million worldwide deaths (71%) emerged from non-communicable diseases, 80% of which emanated from cancers, CVDs, chronic respiratory diseases, and diabetes mellitus (DM) (2); however, interestingly, about half of these cases have arisen from CVDs alone (3).
Although several strategies have been suggested to shrink the mortality rate of CVDs resulting in 39% decrease in the age-related mortality, the global deaths from CVDs have increased by 41% over the past two decades (from 1990 to 2013), primarily as a result of population growth (resulting in 55% increase in the mortality rate) and population aging (resulting in 25% increase in the mortality rate) (4). Accordingly, research has been advanced toward the risk factors of CVDs, specifically coronary artery diseases (CADs) as the main cause of mortality of CVDs in order to develop the preventive strategies for CVDs (5,6).
Moreover, studies on the risk factors of myocardial infarction (MI) and CVDs have touched upon the participants' sex as a critical and determinant indicator (7). It has been identified that women experience their first MI about 10 years later than men, while this difference appears to attenuate after menopause (8). A body of evidence also suggests that this difference projects likely as the result of altered immune response during atherosclerosis triggered by sex hormones (9). Androgenic hormones may play a significant role in the onset and progression of CVD in men as testosterone produces vasorelaxation, improves the endothelial function, and has an atheroprotective effect resulting in a lower risk of MI in older men after andropause (10,11). However, results of a meta-analysis suggest the controversy on the effect of testosterone-replacement therapy on older men around the incidence of MI (12).
On the basis of these controversial results, the study of the association of serum levels of free T with CADs appears to be necessary. In Iran, the incidence rate of MI in men seems to be three times higher than in women but the effect of sex hormones on the risk of MI remains yet to be known (13).

Statistical analysis
The results of the numerical variables are presented as mean ± standard deviation (SD) and compared between the groups using t test
As set out in Table III

Discussion
The results of this study suggested the serum level of free and total testosterone in the group candidate for CABG being significantly lower In another study, Malkin and colleagues suggested that testosterone deficiency is a common finding in participants with CAD, being inversely associated with their survival (16); this is consonant with the results of the present study as we too did not notice any patient with an upperlimit total or free testosterone or between midrange and upper-limit free testosterone levels.
Although a number of aforementioned studies

Conclusion
The results of the present study demonstrated