Moderate doses of hGH (0.64 mg/d) improve lipids but not cardiovascular function in GH-deficient adults with normal baseline cardiac function.

CONTEXT

Data regarding effects of lower-dose GH on cardiopulmonary function in GH-deficient (GHD) adults are limited.

OBJECTIVES

The objective was to assess effects of lower-dose GH on exercise capacity and echocardiographic parameters in GHD adults.

DESIGN

The study was a 6-month double-blind, placebo-controlled randomized trial.

SETTING

The study was conducted at the General Clinical Research Center.

PARTICIPANTS

Thirty hypopituitary adults with GHD were studied.

INTERVENTION

Subjects were randomized to recombinant human GH or placebo for 6 months, followed by open-label recombinant human GH for 12 months.

MAIN OUTCOME MEASURES

Primary endpoints were exercise duration, maximal oxygen consumption, and left ventricular ejection fraction. Secondary endpoints were echocardiographic indices of systolic and diastolic function, left ventricular mass, lipids, and body composition.

RESULTS

In the 6-month double-blind phase, mean GH dose was 0.64 mg/d. Mean IGF-I sd score increased from -4.5 to -1.0. Exercise duration, maximal oxygen consumption, left ventricular ejection fraction, and other echocardiographic parameters were normal at baseline and did not change. GH decreased total and low-density lipoprotein cholesterol by 7.5% (P = 0.016) and 14.7% (P = 0.002) (P = 0.04 vs. placebo). Mean lean body mass increased by 2.2 kg (P = 0.004), fat mass decreased by 1.7 kg (P = 0.21), and percent body fat decreased by 2.5% (P = 0.018), although between-group changes were not significant.

CONCLUSIONS

Human GH did not improve exercise performance or echocardiographic parameters or decrease fat mass but significantly decreased total and low-density lipoprotein cholesterol, increased IGF-I, and increased lean body mass. These results indicate that responses to human GH are variable and should be assessed at baseline and during treatment.