title: Biological variation of retinoids in man.
abstract: This investigation was undertaken to assess biological variation, especially the within-subject variations of all-trans retinoic acid, 13-cis retinoic acid and retinol in human serum. Diurnal variation and variation over a week, a month and a year were studied in 11 males (aged 21-54 years) and 17 females (aged 22-63 years), all subjectively healthy. We found no diurnal variation with the exception of all-trans retinoic acid, which had maximal concentrations at noon irrespective of food intake. Seasonal variations were marginal. Both all-trans and 13-cis retinoic acids had fairly high within-subject (13.1%, and 12.6%, respectively) and between-subject coefficients of variation (15.9% and 21.0%, respectively), while the within-subject CV of retinol was less (5.6%, with a between-subject CV of 21.1%). Thus, the indices of individuality were < 1 for all retinoids. The critical differences between two consecutive samples were < 40% for the retinoic acids and < 20% for retinol. Women had higher all-trans retinoic acid concentrations in serum (5.1 nmol/L vs. 4.5 nmol/L), lower 13-cis retinoic acid concentrations (4.5 nmol/L vs. 5.5 nmol/L) and lower retinol concentrations in serum (2.1 micromol/L vs. 2.5 micromol/L) than men. Thus, samples for retinoid determinations should be drawn in the morning and evaluated using separate gender reference intervals.
authors.affiliation: Institute of Laboratory Medicine, Department of Clinical Chemistry, Lund University, Lund, Sweden. maria.berggren_soderlund@klinkem.lu.se
authors.forename: M Berggren
authors.initials: MB
authors.lastname: Söderlund
authors.forename: A
authors.initials: A
authors.lastname: Sjöberg
authors.forename: G
authors.initials: G
authors.lastname: Svärd
authors.forename: G
authors.initials: G
authors.lastname: Fex
authors.forename: P
authors.initials: P
authors.lastname: Nilsson-Ehle
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D005260:Female; D014644:Genetic Variation; D006801:Humans; D015474:Isotretinoin / Q000097:blood; D008297:Male; D008875:Middle Aged; D012176:Retinoids / Q000097:blood*; D012621:Seasons; D012727:Sex Characteristics; D014212:Tretinoin / Q000097:blood; D014801:Vitamin A / Q000097:blood
chemical_list: D012176:Retinoids; D014801:Vitamin A; D014212:Tretinoin; D015474:Isotretinoin