Factors associated with plasma ghrelin level in Japanese general population

Objective Ghrelin is a novel gastric peptide identified in 1999 as a 'hunger hormone'. Plasma ghrelin level is decreased in human obesity. Factors associated with ghrelin have been mainly investigated in western countries where the prevalence of obesity is high. The aim of this study is to examine factors associated with plasma ghrelin in a Japanese general population where obesity is not so common. Methods Fasting ghrelin levels were measured by ELISA in 638 subjects in 2005-2007. We measured body mass index (BMI), waist circumference and blood pressure. Blood was drawn in the morning after a 12-h fast for determinations of ghrelin, lipid, glucose (FPG), insulin, estimated glomerular filtration rate (eGFR) and uric acid levels. Univariate and multiple stepwise regression analyses were performed to find out factors associated with ghrelin. Results In our population, the mean BMI was 23 center dot 8 kg/m2, indicating a nonobese population. Results of univariate analysis showed that age (P < 0 center dot 001), BMI (P < 0 center dot 001), waist (P < 0 center dot 001), triglycerides (P < 0 center dot 01), FPG (P < 0 center dot 01), insulin (P < 0 center dot 001) and uric acid (P < 0 center dot 05) were inversely associated with ghrelin. High-density lipoprotein (HDL) cholesterol (P < 0 center dot 001) and eGFR (P < 0 center dot 05) were positively associated with ghrelin. Men had lower ghrelin levels than women (P < 0 center dot 001). Results of the multiple stepwise regression analysis revealed that age (P < 0 center dot 001; inversely), female gender (P < 0 center dot 001), insulin (P < 0 center dot 001; inversely), HDL cholesterol (P = 0 center dot 005), BMI (P = 0 center dot 01; inversely) and uric acid (P = 0 center dot 045; inversely) were significantly and independently associated with ghrelin. Conclusions The present study demonstrated that age and gender affected plasma ghrelin levels more than BMI. This may well be because of the low prevalence of overweight in our population.