Testosterone, hemostasis, and cardiovascular diseases in men

Men have a higher incidence of cardiovascular disease (CVD) than women, and adverse thrombotic events increase with age. Recent experimental cross-sectional, and case-control studies have shown that testosterone may affect the hemostatic/fibrinolytic system in men in several ways. It has been hypothesized that physiological doses of testosterone would have a beneficial effect on tissue factor-induced thrombin generation and the development of CVD. The search for eternal youth has created a market for testosterone treatment in aging men during the last few years. However, whether testosterone supplementation could be useful in the treatment of testosterone-deficient elderly men is still controversial. The present review focuses on the coagulation system and CVD from the perspective of testosterone.

Low testosterone and sex hormone-binding globulin levels and high estradiol levels are independent predictors of type 2 diabetes in men

OBJECTIVE

To study the impact of endogenous sex hormone levels in community-dwelling men on later risk for type 2 diabetes.

DESIGN

Population-based prospective cohort study.

METHODS

For the analyses, 1454 men who participated in the fourth Tromsø study (1994-1995) were used. Cases of diabetes were retrieved and validated until 31.12.05 following a detailed protocol. The prospective association between sex hormones and diabetes was examined using Cox proportional hazard regression analysis, allowing for multivariate adjustments.

RESULTS

There was a significantly lowered multi-adjusted risk for later diabetes with higher normal total testosterone levels, both linearly per s.d. increase (hazard ratio (HR) 0.71, confidence interval (CI) 0.54-0.92) and in the higher quartiles of total testosterone than in the lowest quartiles (HR 0.53, CI 0.33-0.84). A reduced multi-adjusted risk for incident diabetes was also found for men with higher sex hormone-binding globulin (SHBG) levels, both linearly per s.d. increase (HR 0.55, CI 0.39-0.79) and when comparing the third (HR 0.38, CI 0.18-0.81) and the fourth quartile (HR 0.37, CI 0.17-0.82) to the lowest quartile. The associations with total testosterone and SHBG were no longer significant after inclusion of waist circumference to the multivariate models. Estradiol (E(2)) was positively associated with incident diabetes after multivariate adjustments including waist circumference when comparing the second (HR 0.49, CI 0.26-0.93) and the third (HR 0.51, CI 0.27-0.96) quartile to the highest quartile.

CONCLUSION

Men with higher E(2) levels had an increased risk of later diabetes independent of obesity, while men with lower total testosterone and SHBG had an increased risk of diabetes that appeared to be dependent on obesity.

Endogenous sex hormones and the prospective association with cardiovascular disease and mortality in men: the Tromsø Study

OBJECTIVE

To study the impact of endogenous testosterone levels in community-dwelling men on later risk for myocardial infarction (MI) and all-cause, cardiovascular disease (CVD), and ischemic heart disease (IHD) mortality.

DESIGN

Population-based prospective cohort study.

METHODS

For the analyses, we used a cohort of 1568 randomly selected men, with sex-hormone data participating in the fourth Tromsø Study (1994-1995). Defined end points were first-ever MI (fatal or nonfatal), all-cause, CVD, and IHD mortality. A committee performed thorough ascertainment of end points, following a detailed protocol. Complete ascertainment of end points was until 30 September 2007 for all-cause mortality, until 31 December 2005 for CVD/IHD mortality, and until 31 December 2004 for first-ever MI. The prospective association between total and free testosterone and end points were examined using Cox proportional hazard regression, allowing for multivariate adjustment for age and cardiovascular risk factors.

RESULTS

During follow-up, there were 395 deaths from all causes, 130 deaths from CVD and 80 deaths from IHD, while 144 men experienced a first-ever MI. There was a significant increase in all-cause mortality risk for men with free testosterone in the lowest quartile (<158 pmol/l) compared with the higher quartiles after age adjustment hazard ratios (HR 1.24, 95% confidence interval, CI 1.01-1.53) and after multivariate adjustments (HR 1.24, 95% CI 1.01-1.54). Total testosterone was not associated with mortality risk. Likewise, there were no significant changes in risk for first-ever MI across different total or free testosterone levels.

CONCLUSION

Men with free testosterone levels in the lowest quartile had a 24% increased risk of all-cause mortality.

The 118 A > G polymorphism in the human mu-opioid receptor gene may increase morphine requirements in patients with pain caused by malignant disease

BACKGROUND

Dispositions for genes encoding opioid receptors may explain some variability in morphine efficacy. Experimental studies show that morphine and morphine-6-glucuronide are less effective in individuals carrying variant alleles caused by the 118 A > G polymorphism in the mu-opioid receptor gene (OPRM1). The purpose of the study was to investigate whether this and other genetic polymorphisms in OPRM1 influence the efficacy of morphine in cancer pain patients.

METHODS

We screened 207 cancer pain patients on oral morphine treatment for four frequent OPRM1 gene polymorphisms. The polymorphisms were the -172 G > T polymorphism in the 5'untranslated region of exon 1, the 118 A > G polymorphism in exon 1, and the IVS2 + 31 G > A and IVS2 + 691 G > C polymorphisms, both in intron 2. Ninety-nine patients with adequately controlled pain were included in an analysis comparing morphine doses and serum concentrations of morphine and morphine metabolites in the different genotypes for the OPRM1 polymorphisms.

RESULTS

No differences related to the -172 G > T, the IVS2 + 31 G > A and the IVS2 + 691 G > C polymorphisms were observed. Patients homozygous for the variant G allele of the 118 A > G polymorphism (n = 4) needed more morphine to achieve pain control, compared to heterozygous (n = 17) and homozygous wild-type (n = 78) individuals. This difference was not explained by other factors such as duration of morphine treatment, performance status, time since diagnosis, time until death, or adverse symptoms.

CONCLUSION

Patients homozygous for the 118 G allele of the mu-opioid receptor need higher morphine doses to achieve pain control. Thus, genetic variation at the gene encoding the mu-opioid receptor contributes to variability in patients' responses to morphine.

[Air pollution and cardiovascular disease in Trondheim]

BACKGROUND

There is some evidence linking air pollution to cardiovascular morbidity. Our aim was to examine whether there is a correlation between air pollution and cardiovascular morbidity in the city of Trondheim, Norway.

MATERIAL AND METHODS

We compared the mean daily number of admissions for cardiovascular disease to the St. Olav University hospital on days with relatively low and high levels of PM10 (1993-2001), PM2,5, NO, NO2, SO2, O3, toluene and paraxylene (1998-2001). A time series analysis was carried out to see how day-to-day variations in concentrations of air pollutants correlated with the number of hospitalizations for cardiovascular disease.

RESULTS

In the bivariate analysis, the mean daily number of hospitalizations was found to be significantly higher (p < 0.05) on days with NO and NO2 levels above the 80 th percentile (57.6 microg/m3 and 43.1 microg/m3, respectively) than on days with pollutant levels below the 20th percentile (11.3 microg/m3 and 16.9 microg/m3, respectively). Time series analysis did not show any statistically significant correlation between day-to-day variations in air pollution and hospital admissions for cardiovascular disease.

INTERPRETATION

The findings regarding NO2 and NO indicate that exposure to gases and/or ultra-small particles from diesel exhaust may influence cardiovascular morbidity.