Can Bone Age Determination Provide Criteria for Growth Hormone Treatment in Adopted Girls with Early Puberty?

Abstract

In treatment of idiopathic central precocious puberty, GnRH analogues (GnRHa) have been accepted as the treatment of choice. Since growth velocity may be impaired with GnRHa treatment growth hormone (GH) treatment has been added in clinical trials. Recently, a study followed adopted girls with early or precocious puberty on GnRHa or combined GnRHa and GH treatment to final height. It was found that final height was significantly higher in the combined treatment group, although the difference was small. It was seen that patients that were extremely short at arrival and short at start of treatment seemed to be candidates for combined treatment.

We have now analysed the data in order to define criteria for the subgroup in need of combined GnRHa-GH treatment in order to achieve normal final height, i.e. above -2 SDS. Bone ages of 46 patients at start of treatment, randomized to either GnRHa treatment or GnRHa treatment combined with GH, were examined blindly by the same radiologist and the PAH calculated. The methods according to Greulich-Pyle / Bayley-Pinneau (GP/BP) and Tanner-Whitehouse (TW2) were used. Predictions versus final height data were analysed. The accuracy of FH prediction was greatest for GnRHa treated group using the GP/BP method. The GP/BP method gave useful cut off limits for when combined treatment was necessary to possibly achieve normal height. If pre-treatment GP/PAH was > 157cm, the patients attained normal height with GnRHa treatment only. Ten out of 13 (77%) such girls could be correctly identified. Using TW2 with a cut off of 164 cm, 9 out of 13 could be selected. Using a multi regression equation of best fit the number of correctly selected cases for GnRHa treatment only, could not be further increased in this group.

We conclude that bone age determination and adult height prediction with the Greulich-Pyle/Bayley-Pinneau method, provides useful criteria for selecting the subgroup of adopted girls with early puberty where combined treatment with GnRHa and GH is not necessary to reach normal final height.