A 24-hour comparison of serum growth hormone concentrations in patients with heart failure versus healthy controls

Study Objective. To compare endogenous serum growth hormone concentrations over a 24-hour period in patients with chronic heart failure (CHF) and matched controls. Design. Prospective, 24-hour, endogenous concentration comparison. Setting. Hospital research center. Patients. Eight evaluable patients with nonischemic dilated cardiomyopathy and 10 healthy control subjects, matched for age and sex. Intervention. Over a 24-hour period, blood was drawn from the study participants every 20 minutes for determination of growth hormone. Measurements and Main Results. For each patient, the area under the concentration-time curve from time 0-24 hours (AUC(0-24)), maximum concentration (Cm,,), and minimum concentration (C-nadir) of growth hormone were determined. The AUC(0-24) and C-max were 74% (p<0.05) and 62% (p<0.05) lower in patients with CHF than in controls, respectively The C-nadir for all participants was 0 mug/L. Variability in growth hormone concentrations over the 24 hours was considerable for all study participants. Conclusions. Growth hormone concentrations are suppressed over a 24-hour period in patients with CHF versus healthy controls. Variability in levels throughout the day suggests that a single point evaluation cannot be used to determine deficiency or abundance of growth hormone.