Does falling testosterone with age among men underlie the increase in ischaemic heart disease

Testosterone: Relationships with Metabolic Disorders in Men-An Observational Study from SPECT-China

BACKGROUND

The strength of associations between total testosterone (TT) and metabolic parameters may vary in different nature of population structure; however, no study has ever given this information in Chinese population, especially those without metabolic syndrome (MS). We aimed to analyze the association magnitudes between TT and multiple metabolic parameters in general Chinese men.

METHODS

4309 men were recruited from SPECT-China study in 2014-2015, which was performed in 22 sites in East China. TT, weight status, and various metabolic parameters were measured. Linear and logistic regressions were used to analyze the associations.

RESULTS

Men in lower TT quartiles had worse metabolic parameters including body mass index, triglycerides, HbA1c, and HOMA-IR (all P for trend < 0.001). Body mass index (B -0.32, 95%CI -0.35 to -0.29) and obesity (OR 0.40, 95%CI 0.35-0.45) had the largest association magnitude per one SD increment in TT, while blood pressure and hypertension (OR 0.90, 95%CI 0.84-0.98) had the smallest. These associations also persisted in individuals without metabolic syndrome.

CONCLUSIONS

Obesity indices had closer relationships with TT than most other metabolic measures with blood pressure the least close. These associations remained robust after adjustment for adiposity and in subjects without metabolic syndrome.

Endogenous androgen exposures and ischemic heart disease, a separate sample Mendelian randomization study

BACKGROUND

Evolutionary biology suggests growth and reproduction trade-off against longevity. Correspondingly estrogen supplementation failed to increase lifespan. Testosterone supplementation is widely used by older men, although regulators have warned of its cardiovascular risk. No large trial of testosterone exists. We examined how genetic determinants of up-regulation (follicle-stimulating hormone (FSH)) and down-regulation (anti-Müllerian hormone (AMH) and testicular dysgenesis syndrome (TDS)) of mainly the male reproductive system are associated with ischemic heart disease (IHD).

METHODS

Separate sample instrumental variable analysis with genetic instruments, i.e., Mendelian randomization, was used to obtain unconfounded estimates using large case-control studies of coronary artery disease/myocardial infarction (CAD/MI) with extensive genotyping, i.e., CARDIoGRAMplusC4D (64,374 CAD/MI cases, 130,681controls), or CARDIoGRAMplusC4D 1000 Genomes (60,801 cases, 123,504 controls).

RESULTS

Genetically predicted FSH was positively associated with CAD/MI (odds ratio (OR) 1.08, 95% confidence interval (CI) 1.03 to 1.13 per mIU/mL FSH). Genetically predicted AMH and TDS were inversely associated with CAD/MI (OR 0.93, 95% CI 0.87 to 0.998 per ng/mL log AMH and OR 0.89, 95% CI 0.81 to 0.98 per log OR higher risk of TDS).

CONCLUSIONS

As expected from evolutionary biology, genetically predicted FSH, related to higher androgens in men and women, was positively associated with IHD, while genetically predicted AMH and TDS, related to lower androgens in men, were inversely associated with IHD. Androgens might be a modifiable causal factor underlying men's greater vulnerability to IHD, with corresponding implications for use of testosterone supplementation as well as for prevention and treatment of IHD.