title: Establishment of testicular endocrine function impairment during childhood and puberty in boys with Klinefelter syndrome.
abstract: OBJECTIVE
  To precisely characterize the chronology of testicular endocrine function impairment during childhood and adolescence in patients with Klinefelter syndrome. Design Retrospective chart review. Patients A total of 29 boys with Klinefelter syndrome with up to 12.3 years follow-up.
  
  
  METHODS
  Clinical features and serum hormone levels were analysed during follow-up.
  
  
  RESULTS
  Of the 29 patients, 16 were prepubertal and 13 had already entered puberty at their first visit. Fifteen patients were followed up through late puberty. Before puberty, LH, FSH, testosterone, anti-Müllerian hormone (AMH) and inhibin B were within the expected range in almost all cases. However, levels of the inhibin alpha-subunit precursor Pro-alphaC were in the lowest levels of the normal range in most cases. During puberty, FSH levels increased earlier and more markedly than LH. Inhibin B and AMH declined to abnormally low or undetectable levels in advanced pubertal stages. Although testosterone and Pro-alphaC levels were within the reference ranges in most cases, they were abnormally low for the observed LH values.
  
  
  CONCLUSIONS
  In Klinefelter syndrome, a mild Leydig cell dysfunction is present from early childhood in most cases and persists throughout puberty. Sertoli cell function is normal until mid puberty, when a dramatic impairment is observed.
authors.affiliation: División de Endocrinología and Centro de Investigaciones Endocrinológicas, Hospital de Niños Ricardo Gutiérrez, Buenos Aires, Argentina.
authors.forename: María Gabriela
authors.initials: MG
authors.lastname: Bastida
authors.forename: Rodolfo A
authors.initials: RA
authors.lastname: Rey
authors.forename: Ignacio
authors.initials: I
authors.lastname: Bergadá
authors.forename: Patricia
authors.initials: P
authors.lastname: Bedecarrás
authors.forename: Luz
authors.initials: L
authors.lastname: Andreone
authors.forename: Graciela
authors.initials: G
authors.lastname: del Rey
authors.forename: Adriana
authors.initials: A
authors.lastname: Boywitt
authors.forename: María Gabriela
authors.initials: MG
authors.lastname: Ropelato
authors.forename: Hamilton
authors.initials: H
authors.lastname: Cassinelli
authors.forename: Andrea
authors.initials: A
authors.lastname: Arcari
authors.forename: Stella
authors.initials: S
authors.lastname: Campo
authors.forename: Silvia
authors.initials: S
authors.lastname: Gottlieb
mesh_terms: D000293:Adolescent; D000818:Animals; D054304:Anti-Mullerian Hormone; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007265:Inhibins / Q000097:blood; D059785:Karyotype; D007713:Klinefelter Syndrome / Q000235:genetics* / Q000503:physiopathology*; D007985:Leydig Cells / Q000473:pathology; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D011498:Protein Precursors / Q000097:blood; D011627:Puberty / Q000097:blood*; D013737:Testis / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D013739:Testosterone / Q000097:blood
chemical_list: D011498:Protein Precursors; C422364:inhibin B; C095971:inhibin-alpha subunit precursor; D013739:Testosterone; D007265:Inhibins; D054304:Anti-Mullerian Hormone; D007986:Luteinizing Hormone