title: Effect of puberty on the relationship between bone markers of turnover and bone mineral density in Turner's syndrome.
abstract: It has been suggested that the appropriate timing of puberty is necessary for normal bone mineral acquisition which may not be achieved amongst patients with Turner's syndrome (TS). The aim of this study was to assess bone mineral density (BMD) and bone turnover in 34 patients with TS (age range 2.2-39.0 years). The areal BMD (aBMD) was determined by dual-energy X-ray absorptiometry, and the volumetric BMD was calculated. Blood and second voided urine samples were taken the morning after an overnight fast for evaluation of the biochemical markers of bone turnover: bone-specific alkaline phosphatase (BAP) and N-telopeptides of type I collagen (NTX), respectively. Both were determined by enzyme-linked immunosorbent assay. The patients were divided into three groups: group 1 (n = 13; prepubertal; age range 2.2-19.0 years), group 2 (n = 10; teenagers; age range 12.4-19.0 years), and group 3 (n = 11; adults; chronological age >20 years). They were also grouped by breast development according to Tanner stage into B1 (n = 12), B2-3 (n = 9), and B4-5 (n = 13). The aBMD was significantly lower in group 1 and was higher at Tanner stages 4 and 5 as compared with patients at Tanner stage 1. The bone turnover markers were significantly higher in group 1 (NTX: p = 0.002; BAP: p = 0.0005) and declined, as puberty progressed. A negative correlation was observed between aBMD and biochemical bone markers at the lumbar spine (NTX: r = -0.54, p = 0.05; BAP: r = -0.44, p = 0.01) and in the whole body (NTX: r = -0.60, p = 0.0008; BAP: r = -0.19, p = 0.002). We conclude that the negative relationships between aBMD and biochemical markers suggest a high bone turnover, mainly in prepubertal patients and that the results observed in relation to aBMD and puberty are imputed to the delayed puberty which occurs amongst TS patients.
authors.affiliation: Department of Endocrinology, Faculty of Medicine, Martagão Gesteira Institute and Clementino Fraga Filho Hospital, Federal University of Rio de Janeiro, Rua Soares Cabral 80/901, Laranjeiras, Rio de Janeiro, RJ 22240-070, Brazil. cgalichio@ig.com.br
authors.forename: Carla T
authors.initials: CT
authors.lastname: Gallicchio
authors.forename: Solange T
authors.initials: ST
authors.lastname: Figueiredo-Alves
authors.forename: Rosângela
authors.initials: R
authors.lastname: Prendin Tórtora
authors.forename: Laura Maria
authors.initials: LM
authors.lastname: Mendonça
authors.forename: Maria Lucia F
authors.initials: ML
authors.lastname: Farias
authors.forename: Marília M
authors.initials: MM
authors.lastname: Guimarães
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000097:blood / Q000652:urine; D015519:Bone Density; D016723:Bone Remodeling; D001842:Bone and Bones / Q000201:enzymology; D002648:Child; D002675:Child, Preschool; D003094:Collagen / Q000652:urine; D024042:Collagen Type I; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism; D010455:Peptides / Q000652:urine; D011627:Puberty; D014424:Turner Syndrome / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000652:urine
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D003094:Collagen; D000469:Alkaline Phosphatase