title: Developmental variations in plasma leptin, leptin soluble receptor and their molar ratio in healthy infants.
abstract: BACKGROUND
  Leptin and its soluble receptor (sOB-R) are important to regulation of body composition but there are no data on the developmental variations in these plasma variables and their relationship with body composition measurements,
  
  
  METHODS
  Weight, length, and body composition (bone, fat and lean mass) by dual energy absorptiometry, and plasma variables were measured in healthy infants at 2, 4, 8 and 12 months.
  
  
  RESULTS
  15 whites and 29 African Americans (21 males and 23 females) with mean birth weight 3357 +/- 45 (SEM) g and gestation of 39.3 +/- 0.17 weeks were studied. The overall Z score for weight, length and weight for length during the study were 0.00 +/- 0.15, -0.08 +/- 0.11 and 0.12 +/- 0.14 respectively. With increasing age, plasma leptin (1.0 to 18.2, median 5.5 ng/mL) and sOB-R:leptin molar ratio (10.1 to 247.4, median 59.9) were lowered (r = -0.47, p < 0.01; and r = -0.37, p < 0.05 respectively), best predicted by weight Z score and percentage of fat mass, and higher in African American and female. Presence of body composition measurements eliminated the race and gender effect on the plasma variables. Plasma sOB-R (49.5 to 173.9, median 81.3 ng/mL) did not change significantly with age and was correlated and predicted only by body composition measurements.
  
  
  CONCLUSIONS
  In healthy growing infants, plasma leptin but not sOB-R decreases with age. Gender, race and anthropometric measurements are additional physiological determinants predictive of plasma leptin and the receptor:ligand ratio. However, body composition is the only variable that can predict plasma leptin and its soluble receptor and the receptor: ligand ratio; and body composition measurements eliminated the race and gender effect on these plasma variables.
authors.affiliation: The Carman and Ann Adams Department of Pediatrics, Wayne State University and Hutzel Hospital, Wayne State University, Detroit, Michigan, USA. wkoo@wayne.edu
authors.forename: Winston W K
authors.initials: WW
authors.lastname: Koo
authors.forename: Mouhanad
authors.initials: M
authors.lastname: Hammami
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hockman
mesh_terms: D001741:Black or African American; D001823:Body Composition / Q000502:physiology*; D001827:Body Height / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D020738:Leptin / Q000097:blood*; D008297:Male; D011956:Receptors, Cell Surface / Q000097:blood* / Q000378:metabolism; D054411:Receptors, Leptin; D012727:Sex Characteristics; D044465:White People
chemical_list: C515448:LEPR protein, human; D020738:Leptin; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin