Older Men with Higher LH at Greater Risk for Ischemic Heart Disease, Study Finds

   Dysregulation of the hypothalamic-pituitary-gonadal axis may be a risk factor for ischemic heart disease (IHD), according to a study presented at ENDO 2011: the 93rd Annual Meeting & Expo of the Endocrine Society in Boston.

   As known, hypogonadism in men is associated with insulin resistance, elevations in pro-inflammatory cytokines and fibrinogen, and an atherogenic lipid profile. But it was uncertain whether age-related decline in testosterone is associated with IHD events.

   Between 2001 and 2004, Australian researchers clinically assessed 3637 community-dwelling men aged 70 to 88 for cardiovascular risk factors and conducted biochemical assessment of testosterone, sex hormone binding globulin (SHBG), and luteinizing hormone (LH).  Free testosterone was estimated. They followed the subjects until December 2008, using electronic records, to capture IHD events (defined as hospital admission or death). The mean followup was 5.1 years.

   Following data analysis, the researchers found that during the followup, 618 men (17.0%; 95% confidence interval [CI], 15.8% to 18.3%) experienced an event, of which 160 were fatal. Men with higher baseline total or free testosterone levels experienced fewer IHD events (hazard ratio [HR] 0.89; 95% CI, 0.82 to 0.97 and HR 0.86; 95% CI, 0.79 to 0.94 for each standard deviation increase in total and free testosterone, respectively). These associations were maintained after adjustment for age and waist:hip ratio, but did not persist after adjustment for prevalent IHD or other cardiovascular risk factors.

   The investigators found no association between SHBG and IHD events. However, higher LH levels were associated with greater incidence of IHD events in both univariate (HR 1.15; 95% CI, 1.08 to 1.22) and adjusted analyses (HR 1.08; 95% CI, 1.01 to 1.15).

   The association between either elevated LH or lower testosterone and ICD warrants further investigation, the Australian researchers concluded.