Higher levels of fasting growth hormone were predictive of increased risk for cardiovascular morbidity and mortality, according to data from the Malmö Diet and Cancer Study.
“Both pathological excess and deficiency of growth hormone (GH) are associated with cardiovascular mortality,” researchers wrote in the Journal of the American College of Cardiology. “The goal of this study was to test whether fasting levels of GH measured with a high-sensitivity assay predict cardiovascular morbidity and mortality at the population level.”
Among the 4,323 participants (mean age, 58 years; 59% women) who were examined from 1991 to 1994, there were 397 coronary artery disease events, 251 strokes, 107 congestive heart failure events, 645 deaths from any cause and 186 cardiovascular (CV) deaths, according to the study results.
Results revealed an independent association between higher fasting levels of GH, as measured by the novel high-sensitivity assay, and increased risk for coronary artery disease (HR=1.11; 95% CI, 1.01-1.23), stroke (HR=1.18; 95% CI, 1.04-1.34), congestive heart failure (HR=1.25; 95% CI, 1.03-1.52), all-cause mortality (HR=1.17; 95% CI, 1.08-1.26) and CV mortality (HR=1.43; 95% CI, 1.24-1.66).
The researchers also noted that adding fasting GH levels to a prediction model that included conventional CV risk factors significantly reclassified risk. Category-free net reclassification improvement was 0.542 (95% CI, 0.205-0.840) in CV mortality, they wrote.
Median follow-up was 16.2 years.
“We demonstrate that higher fasting values of [GH as measured by high-sensitivity assay] are associated with cardiovascular morbidity, all-cause mortality, and, in particular, cardiovascular mortality,” the researchers wrote.
“Further research is needed to elucidate the mechanisms of this association in the general population and its potential implications in the subgroups of patients with a disturbance in GH secretion.”
The researchers acknowledged, however, that their findings are limited by the observational nature of the study. They noted, for instance, that GH secretion is difficult to measure and may vary according to time of day or nutrition.
In an accompanying editorial comment, James A. de Lemos, MD, and Rebecca Vigen, MD, MSCS, both from the University of Texas Southwestern Medical Center in Dallas, highlighted how anabolic hormone use is becoming more common.
Unfortunately, they wrote, this increased use is sometimes actually be abuse, with hormones like testosterone and GH being used by athletes as performance-enhancing substances or by those with borderline hormone deficiencies for cosmetic purposes.
“Despite high rates of unapproved GH use for performance enhancement and anti-aging, there are limited efficacy data to support improvements in physical status,” Drs. de Lemos and Vigen wrote.
They applauded the researchers’ study but noted that the results should be interpreted with caution.
“This interesting study by Hallengren et al should be considered hypothesis-generating and should prompt additional study of the effects of GH on the cardiovascular system,” Drs. de Lemos and Vigen wrote.
“The current situation with testosterone, where cardiovascular safety concerns are now emerging after the ‘genie’ was released, should serve as a cautionary tale. Additionally, patients who are using GH for indications beyond those that are U.S. Food and Drug Administration-approved should be informed of the uncertainty regarding benefits of the potential harm,” they concluded.