- Email: [email protected]
Insulin is a more important predictor for leptin than insulin-like growth factor-binding protein 1 and growth hormone
Poster abstracts
147
Insulin is a more important predictor for leptin than insulin-like growth factor-binding protein 1 and growth hormone B. BLilow ~, B. Arhen 2, L. Hagmar 3 and E. M. Erfurth ~ Departments of Internal Medicine 1, Occupational and Environmental Medicine3, University Hospital Lund and The Institute of Medicine 2, Lund University, Maim6, Sweden
Introduction: Leptin is strongly related to fat mass, but it is also regulated by insulin and sex hormones. Previous investigations have shown a negative association between leptin and insulinlike growth factor-binding protein 1 (IGFBP-1). Studies examining the importance of the effects of growth hormone (GH) deficiency on leptin production have been inconclusive, probably because of differences in the matching of patients and controls. Higher IGFBP-1 levels in patients with GH deficiency (GHD) may also have affected these results. Aims: The aim of the present study was to investigate the relationship between leptin and ICFBP-1 in women with hypopituitarism receiving conventional hormone treatment, but with unsubstituted CHD. Patients and Methods: Fasting levels of insulin, IGFBP-1 and leptin were analysed in 33 women, who had hypopituitarism for a median period of 18 years (range, 6-46 years) and in a population-based control group matched for sex, age, smoking habits and education. Patients and controls were compared using the Wilcoxon matched pair, signed rank test. Univariate correlation was assessed using Spearman's rank order correlation test. There was no significant difference in body mass index (BMI) between patients and the control population (P = 0.4), but waist:hip ratio was higher in patients (P = 0.01). The patients with hypopitu-
itarism had significantly lower serum insulin-like growth factor I levels than the control group (median [range]: 62 ggff [21148 ggff] vs 158 ggff [89-265 gg/1]; P < 0.001). Results-There were no significant differences between patients and controls in serum leptin (median [range]: 17.2 ng/ml [4.9-66.7ng/ml] vs 15.7ng/ml [4.2-44.9ng/ml]; P = 0.4) or serum insulin (median [range]: 7mUff [4-32mU/1] vs 9mU/1 [5-46 muff]; P = 0.3). Serum IGFBP-1 was higher in patients than in healthy controls (median [range]: 53.0ggff [5.5100.0 gg/1] vs 31.0 gg/1 [6.3-7t.0 gg/1]; P = 0.002). Serum IGFBP1 was, in the patient group, negatively correlated with serum leptin (r= -0.40, P = 0.02) and with insulin (r= -0.52, P = 0.002). Serum leptin and serum insulin were positively correlated (r = 0.67, P < 0.001). After adjustment for insulin in a multiple linear regression model, the association between leptin and IGFBP-1 disappeared. Conclusions: There was no difference in leptin levels between women with hypopituitarism and a closely matched control group with similar BMI, even though IGFBP-1 was higher in the patient group. Leptin did not correlate with IGFBP1 after adjustment for insulin. Thus, insulin is a more potent predictor for leptin than IGFBP-1 or GHD.
147
Insulin is a more important predictor for leptin than insulin-like growth factor-binding protein 1 and growth hormone B. BLilow ~, B. Arhen 2, L. Hagmar 3 and E. M. Erfurth ~ Departments of Internal Medicine 1, Occupational and Environmental Medicine3, University Hospital Lund and The Institute of Medicine 2, Lund University, Maim6, Sweden
Introduction: Leptin is strongly related to fat mass, but it is also regulated by insulin and sex hormones. Previous investigations have shown a negative association between leptin and insulinlike growth factor-binding protein 1 (IGFBP-1). Studies examining the importance of the effects of growth hormone (GH) deficiency on leptin production have been inconclusive, probably because of differences in the matching of patients and controls. Higher IGFBP-1 levels in patients with GH deficiency (GHD) may also have affected these results. Aims: The aim of the present study was to investigate the relationship between leptin and ICFBP-1 in women with hypopituitarism receiving conventional hormone treatment, but with unsubstituted CHD. Patients and Methods: Fasting levels of insulin, IGFBP-1 and leptin were analysed in 33 women, who had hypopituitarism for a median period of 18 years (range, 6-46 years) and in a population-based control group matched for sex, age, smoking habits and education. Patients and controls were compared using the Wilcoxon matched pair, signed rank test. Univariate correlation was assessed using Spearman's rank order correlation test. There was no significant difference in body mass index (BMI) between patients and the control population (P = 0.4), but waist:hip ratio was higher in patients (P = 0.01). The patients with hypopitu-
itarism had significantly lower serum insulin-like growth factor I levels than the control group (median [range]: 62 ggff [21148 ggff] vs 158 ggff [89-265 gg/1]; P < 0.001). Results-There were no significant differences between patients and controls in serum leptin (median [range]: 17.2 ng/ml [4.9-66.7ng/ml] vs 15.7ng/ml [4.2-44.9ng/ml]; P = 0.4) or serum insulin (median [range]: 7mUff [4-32mU/1] vs 9mU/1 [5-46 muff]; P = 0.3). Serum IGFBP-1 was higher in patients than in healthy controls (median [range]: 53.0ggff [5.5100.0 gg/1] vs 31.0 gg/1 [6.3-7t.0 gg/1]; P = 0.002). Serum IGFBP1 was, in the patient group, negatively correlated with serum leptin (r= -0.40, P = 0.02) and with insulin (r= -0.52, P = 0.002). Serum leptin and serum insulin were positively correlated (r = 0.67, P < 0.001). After adjustment for insulin in a multiple linear regression model, the association between leptin and IGFBP-1 disappeared. Conclusions: There was no difference in leptin levels between women with hypopituitarism and a closely matched control group with similar BMI, even though IGFBP-1 was higher in the patient group. Leptin did not correlate with IGFBP1 after adjustment for insulin. Thus, insulin is a more potent predictor for leptin than IGFBP-1 or GHD.