title: A seasonal variation of calcitropic hormones, bone turnover and bone mineral density in early and mid-puberty girls - a cross-sectional study.
abstract: The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11.4 (sd 0.4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (P < 0.01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r -0.325, P < 0.001). Moreover, the BMD in the femur (P = 0.047) and to a lesser extent in vertebrae (P = 0.057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7.0-7.6 % difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.
authors.affiliation: Calcium Research Unit, Department of Applied Chemistry and Microbiology, University of Helsinki, Helsinki, Finland. heli.viljakainen@helsinki.fi
authors.forename: Heli T
authors.initials: HT
authors.lastname: Viljakainen
authors.forename: Anette
authors.initials: A
authors.lastname: Palssa
authors.forename: Merja
authors.initials: M
authors.lastname: Kärkkäinen
authors.forename: Jette
authors.initials: J
authors.lastname: Jakobsen
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Cashman
authors.forename: Christian
authors.initials: C
authors.lastname: Mølgaard
authors.forename: Christel
authors.initials: C
authors.lastname: Lamberg-Allardt
mesh_terms: D000293:Adolescent; D000596:Amino Acids / Q000652:urine; D015415:Biomarkers / Q000097:blood / Q000652:urine; D015519:Bone Density / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology; D001842:Bone and Bones / Q000378:metabolism*; D002136:Calcium, Dietary / Q000008:administration & dosage; D003430:Cross-Sectional Studies; D004032:Diet; D005260:Female; D005269:Femur / Q000378:metabolism; D006801:Humans; D008159:Lumbar Vertebrae / Q000378:metabolism; D015675:Osteocalcin / Q000097:blood; D010281:Parathyroid Hormone / Q000097:blood*; D011627:Puberty / Q000502:physiology*; D012621:Seasons; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D015675:Osteocalcin; D014807:Vitamin D; C015484:pyridinoline; C036020:deoxypyridinoline; C104450:25-hydroxyvitamin D