Relationships of blood circulating melanocortins to childhood obesity are not well established. We evaluated serum alpha-melanocyte-stimulating hormone (alpha-MSH) in lean children and different study groups of childhood obesity. We examined serum alpha-MSH in 52 otherwise healthy children with childhood obesity (Ob; mean age, 11 years; 32 girls/20 boys), 27 normal-weight children of same age, 7 additional obese patients with reduced melanocortin-4 receptor function (MC4Rmut), and 22 patients with craniopharyngioma (CP). Fasting serum alpha-MSH and leptin were measured by radioimmunoassay. Serum alpha-MSH was also evaluated 1 hour after 500-kcal liquid meal (CP and Ob) and at the end of 1-year lifestyle intervention in 24 Ob patients. The alpha-MSH levels were similar in obese vs lean children but significantly lower in CP (P < .001) and significantly higher (P < .05) in MC4Rmut patients compared with Ob. One hour after liquid meal, alpha-MSH increased in patients with Ob but not with CP. After 1 year, alpha-MSH levels increased significantly in the successful weight reduction Ob subgroup despite unchanged cortisol levels. The alpha-MSH changes correlated to weight status changes (r = 0.67, P = .0003) but not to changes of cortisol, insulin, or homeostasis model assessment of insulin resistance index. Persistently low alpha-MSH levels in CP patients are suspected to be due to pituitary or hypothalamic damage. High peripheral levels in MC4Rmut carriers indicate up-regulation of alpha-MSH. Changes of weight status are associated with changes of peripheral alpha-MSH.
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