Visceral adipose tissue is associated with circulating high affinity growth hormone-binding protein

Recent data show that body fat distribution, specifically visceral fat accumulation, is associated with the regulation of GH secretion. To our knowledge no studies have been performed with regard to the relationship between plasma high affinity GH-binding protein (GHBP) levels and fat distribution in humans. To address this question, we measured plasma GHBP and insulin-like growth factor I levels as well as visceral, sc abdominal, and hip adipose tissue (AT) areas by using magnetic resonance imaging scanning in 12 patients with GH deficiency (GHD) and in 12 age- and sex-matched healthy subjects. The GHD patients were subsequently treated with GH replacement therapy. Regardless of the GH status of the subjects, body mass index and visceral AT area were positively correlated to plasma GHBP (r = 0.70; P < 0.01 and r = 0.73; P < 0.01, respectively), whereas the sc AT areas at the abdominal level tended to correlate positively with GHBP levels, but did not reach significance (r = 0.44; P = 0.07). The sc AT areas at the hip level were not correlated with plasma GHBP levels. In the GHD patients the pretreatment visceral and abdominal sc AT areas were positively correlated with the change in GHBP levels after GH replacement (r = 0.82; P < 0.01 and r = 0.75; P < 0.01, respectively). The pretreatment sc AT area at the hip level was not associated with the therapy-induced changes in plasma GHBP (r = 0.28; P > 0.10). In summary, this study shows that visceral fat is associated with circulating GHBP levels, suggesting that visceral fat mass may be involved in the regulation of the plasma GHBP level. Further, the amount of abdominal fat in GHD patients may partially determine the plasma GHBP response to GH replacement therapy.