title: Selective reduction in cortical bone mineral density in turner syndrome independent of ovarian hormone deficiency.
abstract: Women with Turner syndrome (TS) are at risk for osteoporosis from ovarian failure and possibly from haploinsufficiency for bone-related X-chromosome genes. To establish whether cortical or trabecular bone is predominantly affected, and to control for the ovarian failure, we studied forearm bone mineral density (BMD) in 41 women with TS ages 18-45 yr and in 35 age-matched women with karyotypically normal premature ovarian failure (POF). We measured BMD at the 1/3 distal radius (D-Rad(1/3); predominantly cortical bone) and at the ultradistal radius (UD-Rad; predominantly trabecular bone) by dual x-ray absorptiometry. Women with TS had lower cortical BMD compared with POF (D-Rad(1/3) Z-score = -1.5 +/- 0.8 for TS and 0.08 +/- 0.7 for POF; P < 0.0001). In contrast, the primarily trabecular UD-Rad BMD was normal in TS and not significantly different from POF (Z-score = -0.62 +/- 1.1 for TS and -0.34 +/- 1.0 for POF; P = 0.26). The difference in cortical BMD remained after adjustment for height, age of puberty, lifetime estrogen exposure, and serum 25-hydroxyvitamin D (P = 0.0013). Cortical BMD was independent of serum IGF-I and -II, PTH, and testosterone in TS. We conclude that there is a selective deficiency in forearm cortical bone in TS that appears independent of ovarian hormone exposure and is probably related to X-chromosome gene(s) haploinsufficiency.
authors.affiliation: Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA. bakalov@mail.nih.gov
authors.forename: Vladimir K
authors.initials: VK
authors.lastname: Bakalov
authors.forename: Lauren
authors.initials: L
authors.lastname: Axelrod
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Baron
authors.forename: Lori
authors.initials: L
authors.lastname: Hanton
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Nelson
authors.forename: James C
authors.initials: JC
authors.lastname: Reynolds
authors.forename: Suvimol
authors.initials: S
authors.lastname: Hill
authors.forename: James
authors.initials: J
authors.lastname: Troendle
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Bondy
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density; D004967:Estrogens / Q000172:deficiency*; D005260:Female; D006801:Humans; D016649:Primary Ovarian Insufficiency / Q000378:metabolism; D011884:Radius / Q000378:metabolism*; D014424:Turner Syndrome / Q000378:metabolism*
chemical_list: D004967:Estrogens