title: Prolactin secretion in healthy adults is determined by gender, age and body mass index.
abstract: BACKGROUND
  Prolactin (PRL) secretion is quantifiable as mean, peak and nadir PRL concentrations, degree of irregularity (ApEn, approximate entropy) and spikiness (brief staccato-like fluctuations).
  
  
  OBJECTIVE
  Distinct PRL dynamics reflect relatively distinct (combinations of) subject variables, such as gender, age, and BMI.
  
  
  METHODS
  Clinical Research Unit.
  
  
  METHODS
  Seventy-four healthy adults aged 22-77 yr (41 women and 33 men), with BMI 18.3-39.4 kg/m(2).
  
  
  METHODS
  Immunofluorometric PRL assay of 10-min samples collected for 24 hours.
  
  
  RESULTS
  Mean 24-h PRL concentration correlated jointly with gender (P<0.0001) and BMI (P = 0.01), but not with age (overall R(2) = 0.308, P<0.0001). Nadir PRL concentration correlated with gender only (P = 0.017) and peak PRL with gender (P<0.001) and negatively with age (P<0.003), overall R(2) = 0.325, P<0.0001. Forward-selection multivariate regression of PRL deconvolution results demonstrated that basal (nonpulsatile) PRL secretion tended to be associated with BMI (R(2) = 0.058, P = 0.03), pulsatile secretion with gender (R(2) = 0.152, P = 0.003), and total secretion with gender and BMI (R(2) = 0.204, P<0.0001). Pulse mass was associated with gender (P = 0.001) and with a negative tendency to age (P = 0.038). In male subjects older than 50 yr (but not in women) approximate entropy was increased (0.942±0.301 vs. 1.258±0.267, P = 0.007) compared with younger men, as well as spikiness (0.363±0.122 vs. 0463±2.12, P = 0.031). Cosinor analysis disclosed higher mesor and amplitude in females than in men, but the acrophase was gender-independent. The acrophase was determined by age and BMI (R(2) = 0.186, P = 0.001).
  
  
  CONCLUSIONS
  In healthy adults, selective combinations of gender, age, and BMI specify distinct PRL dynamics, thus requiring balanced representation of these variables in comparative PRL studies.
authors.affiliation: Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands. f.roelfsema@lumc.nl
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Roelfsema
authors.forename: Hanno
authors.initials: H
authors.lastname: Pijl
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Keenan
authors.forename: Johannes D
authors.initials: JD
authors.lastname: Veldhuis
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D015992:Body Mass Index; D005260:Female; D006262:Health; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood; D017697:Premenopause / Q000097:blood; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D012727:Sex Characteristics; D013997:Time Factors; D055815:Young Adult
chemical_list: D011388:Prolactin