Endocrine Abstracts

Leptin is an adipocytokine with a role in appetite, energy expenditure and reproductive regulation. In normal, non-obese individuals, leptin levels are higher in females, independent of differences in body fat between the genders. High levels of leptin that were disproportionate to body mass index (BMI) have been reported in craniopharyngioma patients, thus we hypothesised that surgical resection and hypothalamic damage conferred leptin resistance on craniopharyngioma patients, and hence that gender and circadian variation of leptin levels would be lost in this group.

Fifteen patients (8 male) with craniopharyngioma were identified from the local pituitary database and consented to participate in the study. Patients were advised to eat their midday meal as normal and to avoid snacking in the afternoon prior to sampling. Height and weight were measured for calculation of BMI, (range 26–61 kg/m²). Venous blood samples were taken between 5 and 6pm and repeated the following morning after a ten-hour fast. Samples were centrifuged and stored at −80  °C. The samples were assessed using a radioimmunoassay (Mediagnost, Germany). Local ethics committee approval was obtained for the study.

Fasting morning leptin levels were significantly higher in female patients (mean±S.E.M.: 55.51 ng/ml ±8.23) than in male patients (20.06±7.1 ng/ml, P<0.01, t-test). Evening leptin measurements were also higher in female patients (37.98±6.27 ng/ml) than in male patients (17.5±5.3 ng/ml, P<0.05). Morning leptin levels were higher than evening levels in the overall group (31.69±7.2 vs 26.0±5.3 ng/ml, P=0.02 paired t-test).

In this group of patients with craniopharyngioma and hypothalamic obesity, the normal pattern of leptin secretion was preserved.