# The relationship between pituitary size and the response to recombinant human growth hormone therapy in children with isolated growth hormone deficiency

## TL;DR

The study finds that children with smaller pituitary glands respond better to growth hormone therapy for short stature.

## Contribution

This study identifies pituitary size as a novel predictor of growth response to rhGH therapy in children with isolated GHD.

## Key findings

- Smaller pituitary height correlates with better height and IGF1 improvements during rhGH therapy.
- Pituitary volume measured by ellipsoid method shows stronger negative correlations with growth outcomes.
- Good responders to rhGH therapy have significantly lower pituitary volume SDS compared to poor responders.

## Abstract

Growth hormone deficiency (GHD) is one of the major endocrine causes of short stature in childhood. Pituitary size may reflect growth hormone secretory capacity; and children with hypoplastic pituitary exhibit more severe GHD. Given this relationship, pituitary size may also serve as a valuable predictor of the growth response to recombinant human growth hormone (rhGH) therapy. This study aimed to investigate the relationship between pituitary height and volume measured on MRI and the growth response to rhGH therapy in children with GHD.

This retrospective, single-center study included 52 children with isolated GHD. Pretreatment pituitary MRI was evaluated for pituitary height and volumetric assessment. Two different methods were used to estimate pituitary volume: the classical ellipsoid formula and and the cross-sectional area. Pituitary volume SDS values were calculated according to age- and sex. Growth response to therapy was measured using height velocity (HV), HV SDS, ΔHeight SDS (change in height SDS between baseline and the end of the first year of the treatment), and ΔIGF1 SDS (change in IGF1 SDS between baseline and the end of the first year of the treatment).

The median age of the patients at diagnosis was 8.1 years (IQR: 4.4-11.4). At diagnosis, patients showed marked growth failure with a median height SDS of -2.84 (IQR: −3.65 to −2.44). Statistically significant negative correlation was observed between pituitary height and both ΔHeight SDS and ΔIGF1 SDS. Pituitary volume calculated by the ellipsoid method showed statistically significant negative correlations with HV, HV SDS, and ΔHeight SDS at the end of the first year of rhGH therapy (p < 0.05). Pituitary volume calculated by the cross-sectional area method only showed statistically significant negative correlation with HV SDS. When patients were categorized based on their response to rhGH therapy, those in the good-response group (HV SDS > 2) had significantly lower pituitary volume SDS calculated by the ellipsoid method compared to poor responders (p = 0.021).

Our findings indicate that smaller pituitary size is associated with a more favorable growth response to rhGH therapy in children with isolated GHD.