1. ¹Department of Endocrinology, Centre of Excellence on Neurodegenerative Diseases, University of Milan, Milan, Italy
2. ²Department of Experimental Pathology, Immunology Section, University of Bologna, Bologna, Italy
3. ³Institute of General Pathology, Laboratory of Clinical Pathology, University of Milan, Milan, Italy

Correspondence: P Magni, Istituto di Endocrinologia, via G. Balzaretti, 9, 20133 Milano, Italy. E-mail: paolo.magni@unimi.it

Guarantor: P Magni.

Contributors: PM and MMC were responsible for the study concept and writing of the manuscript. MR and ED were responsible of the biochemical studies and the literature search. FL was responsible for the clinical management. ER and MM were responsible for the critical revision of the manuscript.

Received 12 November 2003; Revised 3 March 2004; Accepted 5 April 2004; Published online 26 May 2004.

Abstract

Objective: To evaluate plasma total, free (FL) and protein-bound (BL) leptin in children with Down's syndrome (DS) and different degrees of adiposity and its relationship with thyroid stimulating hormone (TSH), free thyroxine (FT₄), and free triiodothyronine (FT₃).

Subjects: A total of 24 prepubertal clinically euthyroid DS children.

Methods: Plasma leptin, TSH, FT₄, and FT₃ concentrations were determined by immunometric/radioimmunologic assays. FL and BL were evaluated by fast protein liquid chromatography.

Results: In DS children, leptin circulates in two fractions, corresponding to BL and FL. The amount of BL and FL is negatively and positively correlated to body mass index (BMI), respectively. Plasma leptin concentrations correlate with BMI, but not with TSH, FT₄, and FT₃.

Conclusions: In prepubertal DS children, leptin circulates as both BL and FL, correlates with adiposity and its concentration appears independent of thyroid function.

Sponsorship: MIUR, Università degli Studi di Milano, Banca Popolare di Milano Foundation.