Evaluation of the response to growth hormone therapy when the decision of treatment was done based on the relation to the mid parental height

Introduction Midparental height (MPH) can be used as a crude prediction of the child’s adult height. Familial short stature (FSS) is a condition in which the final adult height achieved is less than the third percentile for the patient’s age, sex, and population. Nevertheless, it is consistent with parental height in the absence of nutritional, hormonal, acquired, genetic, and iatrogenic causes. The rationale for treating childhood short stature includes increasing height and alleviating psychosocial disability while maintaining favorable risk/benefit and cost/benefit ratios. Selection among management options may therefore depend on the degree to which each meets these goals. Inappropriately, ascribing a child’s extreme shortness to relatively short parents could thus result in delayed investigations or failure to appreciate the seriousness of a child’s situation. Aim The aim of this study is to evaluate the response to growth hormone (GH) therapy when the decision of treatment was made based on their relation to MPH whether FSS or much shorter than their MPH standard deviation score (SDS). Patients and methods This is a retrospective study; we studied the auxologic data of 21 children with FSS [height SDS (HtSDS) <−2, MPHSDS <−2 SD] and 14 children who were not short [HtSDS >−2, but ≥1 SD shorter than their MPHSDS who were treated with recombinant GH (somatropin/norditropin] 0.03–0.05 mg/kg/day daily for more than 1 year, and the dose was adjusted to keep the insulin-like growth factor-1 (IGF-1) level in the upper quartile of normal for age. Results In the FSS group, after an average of 3.27 years on GH treatment, the HtSDS increased by 0.92 SD, and IGF-1 SD increased by 2.87 SD. Difference between the HtSDS and MPHSDS improved significantly from −0.18 to 0.74 SD. In the other group, after GH therapy the HtSDS increased by 0.5 and IGFSDS increased by 3.24 SD. Difference between the HtSDS and MPHSDS improved significantly from −1.26 to −0.72 SD. However, the HtSDS was still more than 0.5 or more lower than the MPHSDS. In both groups, the HtSDS gain was positively correlated with the duration of GH therapy (r=0.52, P=0.01) and negatively correlated with the age at the start of treatment (r=−0.34, P=0.01) and the pretreatment IGF-1 level (r=−0.37, P=0.04). Conclusion GH therapy improved HtSDS even to exceed MPHSDS in children with FSS. Children with normal stature while far below MPHSDS had their HtSDS improved with GH therapy while did not reach their MPHSDS. The duration and age at the start of GH therapy are important parameters for the favorable outcome. MPHSDS is an important parameter in GH therapy decision.