Obese adults with primary growth hormone resistance (Laron Syndrome) have normal endothelial function

Objective: Classic Laron Syndrome (LS) is a recessive disease of insulin-like growth factor I (IGF-I) deficiency and primary growth hormone insensitivity, clinically characterized by dwarfism and marked obesity. The aim of the current study was to investigate the impact of long-term IGF-I deficiency on flow-mediated dilation (FMD) in 11 non-IGF-I-treated LS adults with long-term IGF-I deficiency who on stress echocardiography were found to have reduced cardiac dimensions and output, but normal left ventricular (LV) ejection fraction at rest and LV contractile reserve following stress. Design: Following an overnight fast we assessed percent improvement in endothelium-dependent FMD (%FMD) and endothelium-independent nitroglycerin (%NTG)-mediated vasodilation non-invasively in the brachial artery, using high resolution ultrasound in 11 non-treated adult patients with LS without known coronary artery disease, and compared them to 11 age- and sex-matched healthy controls. All subjects underwent symptom-limited exercise testing (Bruce protocol). Results: LS patients had a significantly higher body mass index (29 +/- 16 vs. 25 +/- 2 kg/m(2), p=0.04), lower low-density lipoprotein cholesterol (142 +/- 128 vs. 176 +/- 12 mg/dl, p=0.03) and a smaller mean brachial artery diameter (4.63 +/- 0.72 vs. 5.70 +/- 1.06 mm, p=0.01) compared to controls. However, brachial artery %FMD and %NTG were not significantly different between the LS patients and controls (13.1 +/- 6.2% vs. 15.4 +/- 5.2%, p=0.28 and 22.3 +/- 6.0% vs. 18.9 +/- 6.2%, p=0.30; respectively). Cardiac performance, assessed by exercise duration time and metabolic equivalents (METs), was significantly greater in control subjects than in LS patients (10.3 +/- 12.0 vs. 6.0 +/- 1.4 min, p<0.01 and 10.2 +/- 2.0 vs. 7.2 +/- 1.4 METs, p<0.01; respectively). Conclusions: FMD was found to be within normal limits in non-IGF-I-treated adult patients with LS, despite congenital absence of IGF-I and obesity. (C) 2007 Elsevier Ltd. All rights reserved.