Endogenous testosterone and mortality risk

The Triglycerides and Glucose Index is not superior to HOMA-IR in predicting testosterone deficiency among adult males

BACKGROUND

Testosterone decline and deficiency in males have aroused increased attention in male health management, which might have a close relationship with insulin resistance (IR).

OBJECTIVES

We utilized a novel and practical IR indicator, the triglyceride-glucose (TyG) index, to investigate the association between the TyG index and serum testosterone in US adult males.

MATERIALS AND METHODS

This was a cross-sectional study based on data from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 and 2015-2016. The TyG index was calculated from fasting plasma glucose and serum triglyceride, and serum testosterone was measured by isotope dilution liquid chromatography tandem mass spectrometry in NHANES.

RESULTS

A total of 2186 male participants aged more than 20 years old were included, and the mean TyG index was 8.72 ± 0.71. Participants with a higher TyG index showed a lower level of total testosterone (β = -45.83, 95% CI: -58.50, -33.15, p < 0.0001) and a higher risk of testosterone deficiency (OR = 1.80, 95% CI: 1.46, 2.21, p < 0.0001) after we adjusted for all potential cofounders. Males in TyG index tertile 3 had a 113% (95% CI: 1.50, 3.02, p < 0.0001) higher risk of testosterone deficiency than those in tertile 1. Subgroup analysis stratified by diabetes condition indicated that the TyG index might be a good predictor of testosterone decline or deficiency in either people with or without diabetes. However, ROC cure analysis indicated that a larger area under the curve was found in the homeostasis model assessment of insulin resistance (HOMA-IR) (0.71, 95% CI: 0.68,0.74) than in the TyG index (0.67, 95% CI: 0.64, 0.70).

CONCLUSIONS

Males with a higher TyG index tended to have a higher risk of testosterone decline or even testosterone deficiency. However, the predictability of the TyG index for testosterone deficiency was not better than that of HOMA-IR. More well-designed studies are still needed to validate this relationship.

Lower testosterone levels are associated with higher risk of death in men

Background and Objectives

Testosterone plays an important role in regulating male development, reproduction and health. Declining levels across the lifespan may reflect, or even contribute to, chronic disease and mortality in men.

Methodology

Relationships between testosterone levels and male mortality were analyzed using data from multiple samples of the cross-sectional National Health and Nutrition Examination Survey (n = 10 225). Target outcomes included known deaths from heart disease, malignant neoplasms, chronic lower respiratory diseases, cerebrovascular diseases, Alzheimer's disease, diabetes mellitus, influenza and pneumonia, kidney diseases, and accidents or unintentional injuries.

Results

Results of discrete-time hazard models revealed that lower levels of testosterone were related to higher mortality for the majority of disease categories in either an age-dependent or age-independent fashion. Analysis of all-cause mortality-which included deaths from any known disease-also revealed greater general risk for those with lower testosterone levels. For most disease categories, the hazard associated with low testosterone was especially evident at older ages when mortality from that particular ailment was already elevated. Notably, testosterone levels were not related to mortality risk for deaths unrelated to chronic disease (i.e. accidents and injuries).

Conclusions and Implications

While the causal direction of relationships between testosterone and mortality risk remains unclear, these results may reflect the decline in testosterone that accompanies many disease states. Accordingly, the relationship between testosterone and male mortality may be indirect; ill individuals are expected to have both lower testosterone and higher mortality risk.

Reproductive axis ageing and fertility in men

Compared to women, increasing male age is not accompanied by such marked changes in reproductive function but changes certainly do happen. These include alterations to the hypothalamo-pituitary-testicular axis, with resultant implications for testosterone production and bioavailability as well as spermatogenesis. There is a decline in sexual function as men age, with a dramatic increase in the prevalence of erectile dysfunction after the age of 40, which is a marker for both clinically evident as well as covert coronary artery disease. Despite a quantitative decline in spermatogenesis and reduced fecundability, the male potential for fertility persists throughout adult life, however there are also increasingly recognised alterations in sperm quality and function with significant implications for offspring health. These changes are relevant to both natural and medically assisted conception.

Prevalence of anemia and association with mortality in community-dwelling elderly in Thailand

Anemia is one of the most common health problems in the elderly in low and middle income countries. Evidence from studies in high income countries suggests that the presence of anemia may predict mortality. We aimed to estimate the prevalence of anemia and the determine the relationship of hemoglobin, mean corpuscular volume (MCV) and mortality in community dwelling Thai elderly. Data from subjects aged ≥ 60 years from the Fourth Thai National Health Examination Survey were analyzed. Comorbidity and hematologic indexes including MCV were obtained. The Cox proportional hazard model was applied to explore associations with mortality. Data from 8,935 subjects were obtained. The mean age of participants was 69.2 years (SD 6.8). 3446 (38.2%) of subjects had anemia; 1931(56%) of these were classified as mild and normocytic. With a total 51,268 person-year of follow up, 753 participants with anemia died, and the cumulative all-cause mortality was 38.5 per 1,000 person-years. The presence of anemia was associated with an increased risk of mortality with HR of 1.66 (95% CI = 1.50-1.84 , p < 0.001). Among subjects with low MCV, hemoglobin level < 10 g/dl in men and < 9 g/dl in women significantly increased the risk of mortality (HR of 2.71, 95% CI = 1.88-3.91 and HR of 3.14, 95%CI = 2.11-4.67, respectively) Persons with anemia and normal MCV, the association with mortality was evident at hemoglobin levels below 11 g/dl for both males and females. (HR of 1.98, 95% CI = 1.67-2.35). Anemia is a moderate to severe public health significant in the population for community dwelling elderly in Thailand. At the same level of Hemoglobin, low MCV population seem to have lower mortality rate than normal MCV. Systematic screening for anemia should be implemented to identify patients at increased risk of mortality. The future research should be focus on causes of anemia and factors contributing to increased mortality in normal to high MCV would be of interest. If this could lead to identifying modifiable causes, it would be beneficial for improving mortality risk among older people.

Erectile dysfunction predicts mortality in middle-aged and older men independent of their sex steroid status

BACKGROUND

erectile dysfunction is associated with mortality, whereas the association between low testosterone (T) and higher mortality remains controversial. Sexual dysfunction and low T often coexist, but the relative importance of sexual symptoms versus low T in predicting mortality is not known. We studied the interrelationships between sex steroids and sexual symptoms with all-cause mortality in a large prospective cohort of European men.

DESIGN

survival status was assessed in 1,788 community-dwelling men, aged 40-79, who participated in the European Male Ageing Study (EMAS). Sexual symptoms were evaluated via a validated questionnaire (EMAS-SFQ). Sex steroids were measured by mass spectrometry. Cox proportional hazard models were used to study the association between hormones, sexual symptoms and mortality.

RESULTS

about 420 (25.3%) men died during a mean follow-up of 12.6 ± 3.1 years. Total T levels were similar in both groups, but free T was lower in those who died. Men with three sexual symptoms (erectile dysfunction, reduced morning erections and lower libido) had a higher mortality risk compared with men with none of these symptoms (adjusted hazard ratio (HR) and 95% confidence intervals: 1.75 (1.28-2.40, P = 0.001)). Particularly, erectile dysfunction and poor morning erections, but not lower libido, were associated with increased mortality (HR 1.40 (1.13-1.74, P = 0.002), 1.28 (1.04-1.59, P = 0.023) and 1.12 (0.90-1.39, P = 0.312), respectively). Further adjusting for total T, free T or oestradiol did not influence the observed risk.

CONCLUSIONS

sexual symptoms, in particular erectile dysfunction, predict all-cause mortality independently of sex steroids and can be an early warning sign of a poor health status.

Conclusions about testosterone therapy and cardiovascular risk

In this issue of Asian Journal of Andrology (AJA), several experts have reviewed the latest data on the potential and known effects of endogenous and exogenous testosterone (T) on cardiovascular risk. In the review by Meyer and Wittert, low endogenous serum T appears to be associated with higher risk of cardiovascular disease and overall mortality in certain populations such as Klinefelter syndrome and older men, but not in men with congenital hypogonadotropic hypogonadism.1 Whether this association is causal or whether low serum testosterone is a marker of other risk factors for cardiovascular disease such as obesity, diabetes mellitus, or other systemic disease is unknown. In Yeap's review of the relationship between circulating endogenous testosterone and its major metabolites, dihydrotestosterone, and estradiol, he raises the provocative hypotheses that there might be differential effects on cardiovascular and cerebrovascular risk related to endogenous testosterone and dihydrotestosterone concentrations.2 Based on the same epidemiological studies, Yeap postulates that there might be a U-shaped curve for circulating endogenous androgen concentrations such that lower and higher concentrations might confer greater risk of cardiovascular events and all-cause mortality than midrange concentrations. Shores demonstrates in a carefully done review of studies of large prescription databases (including >200 000 men) that testosterone therapy is not associated with overall mortality, myocardial infarction, stroke, or deep venous thrombosis events.3