Growth Hormone and Craniofacial Changes: Preliminary Data From Studies in Turner's Syndrome

Normal craniofacial and dental growth and development is dependent on growth hormone (GH) and insulin-like growth factor I (IGF-I). Deficiencies of either during childhood cause diminished growth of the maxilla and (to a greater degree) the mandible. Dental development/eruption also is compromised. Conversely, excessive GH/insulin-like growth factor I causes overgrowth, with the mandible again more affected than the maxilla. Replacement therapy in deficiency conditions generally normalizes craniofacial growth. Systemic GH also has been used in other disorders for which overt deficiency of GH has not been demonstrated. One such condition, Turner's syndrome, is now widely treated with GH. Although systemic GH in Turner's syndrome has been shown to positively affect stature, the effects on craniofacial growth and dental development/eruption are largely unknown. To explore these issues, standardized lateral radiographs of seven untreated patients with Turner's syndrome were analyzed and revealed hypoplasias of the cranial base, maxilla, and mandible. Dental development/eruption of patients with Turner's syndrome was found to be significantly advanced (by 0.63 years), relative to control subjects, in a separate study. Annual radiocephalometric measurements of 19 patients with Turner's syndrome treated with GH were compared with nonaffected control subjects over 1 year of treatment. Compared with age-matched historic control subjects, all maxillary—and most mandibular—growth measures were within 2 standard deviations of control. However, in our patients with Turner's syndrome, we found two measures of mandibular growth that deviated by more than 3 standard deviations from control. These data, although preliminary and only encompassing a short period, indicate that mandibular growth may be more affected than is maxillary growth by GH treatment and should be monitored over long-term-therapy.