ESPE Abstracts

Background: The precision of adult height prediction by bone age determination in children with idiopathic growth hormone deficiency (IGHD) is unknown.

Patients and Methods: The near adult height (NAH) of patients with IGHD with prepubertal onset of growth hormone treatment (GH) in the KIGS database was compared to adult height prediction based on bone ages (BA) >7 years using the Bailey Pinneau (BP) or Tanner-Whitehouse 2 (TW2) method. The study population included 315 children (baseline: 122 girls and 193 males with mean age 10.4y and 11.3y, respectively) with height prediction based on BP method and 121 children (baseline: 22 girls and 99 boys with mean age 10.6y and 10.8y, respectively) with height prediction based on TW2 method. Multiple linear regression analyses adjusted for age at GH start, mean dose of GH treatment, years of GH treatment, and maximum GH peak in GH stimulation test were calculated.

Results: The difference between NAH and target height (median) was -3.3 cm in girls and -3.0 cm in boys. Adult height prediction did not differ significantly (P=0.36) between BP and TW2. The adult height prediction correlated between BP and TW2 at baseline (r=0.74, P<0.001), at 1 year of GH treatment (r=0.82, P<0.001) and at the last performed BA (r=0.87, P<0.001) on average 6 years after baseline. The mean underestimation of NAH based on the BA method was at baseline 4.0 ±0.5 cm in girls and 4.4 ±0.4 in boys, at 1 year of GH treatment 2.0 ±0.3 cm in girls and 0.5 ±0.3 cm in boys, while at last BA NAH was overestimated in mean by 0.4 ±0.4 cm in girls and 3.7 ±0.3 cm in boys. The mean underestimation of NAH based on the TW2 method was at baseline 1.4 ±1.3 cm in girls and 6.6 ±0.6 cm in boys, at 1 year of GH treatment NAH was overestimated in girls 0.9 ±0.6 cm in girls and underestimated 3.8 ±0.4 cm in boys, while at last BA determination NAH was overestimated in mean by 1.1 ±0.9 cm in girls and 4.5 ±0.5 cm in boys.

Conclusions: Height prediction by BA determinations at onset and in the first year of GH treatment underestimates NAH in prepubertal children with IGHD at onset of treatment. In contrast, height prediction by BA at pubertal age in IGHD children treated with GH for a mean of 6 years overestimated NAH.