Plasma leptin levels in male patients with idiopathic central diabetes insipidus

Leptin is known to regulate food intake and energy expenditure. Moreover, r ecent studies in rodents have shown that leptin in high doses decreases uri ne osmolality and increases water intake, together with renal sodium and wa ter excretion. Since it is not clear whether leptin is involved in either t he pathogenesis or in resulting metabolic abnormalities in diabetes insipid us, we measured leptin levels in 16 male patients with idiopathic central d iabetes insipidus (DI) in comparison to a group of age- and BMI-matched mal e control subjects (no.=30). We found that plasma leptin concentration did not differ between patients with DI(4.45+/-3.24 mu g/l) and healthy control group (3.69+/-2.81 mu g/l; t test, p=0.41). Urine osmolality, plasma osmol ality and urine volume of the patients with DI was not correlated to leptin . However, leptin was positively associated with body mass index (r=0.67; p =0.005). We conclude that leptin plasma concentrations are unchanged in dia betes insipidus. Furthermore, the lack of correlation between plasma leptin and urine osmolality, plasma osmolality or urine volume suggests that ADH deficiency does not have any impact on the plasma leptin levels. (C) 1999, Editrice Kurtis.