The relationship of abdominal fat mass assessed by helical or conventional computed tomography to serum leptin concentration.

Abstract

In the present study, we focused on the relationship of intra-abdominal visceral fat (VF) or subcutaneous fat (SF) mass to serum leptin levels, and also on the relationship of leptin to serum lipid and lipoprotein concentration. Subjects with obesity (26 men, 26 women) were recruited for this study. We obtained helical CT scans with a tube current of 150 mA, voltage of 120 kV and 2:1 pitch (table speed in relation to slice thickness), starting at the upper edge of the liver and continuing to the pelvis. The intra-abdominal visceral fat (VF) volume was measured by drawing a line within the muscle wall surrounding the abdominal cavity. The abdominal SF volume was calculated by subtracting the VF volume from the total abdominal fat volume. By comparison, the abdominal VF and SF areas were determined at the umbilical level by the established slice-by-slice CT scanning technique. We found: 1) abdominal SF mass, either as volume or area, was a more important determinant of serum leptin than was VF mass; 2) among TC, TG, HDL-C and LDL-C, only TG had a positive correlation to serum leptin levels in men, whereas in women no lipid parameters had any relationship with leptin; and 3) VF mass had a positive correlation to serum TC and TG in men, whereas SF did not. The present study provides considerable evidence on the relationship between abdominal fat mass and serum leptin, and shows that the relationships between serum leptin and serum lipids and lipoproteins are not straightforward. We also suggest that fat area measured by conventional CT is a better indicator than its corresponding volume assessed by helical CT, based on the present results showing its closer association to serum lipids.