Magnetic resonance images of 91 children with different causes of short stature: pituitary size reflects growth hormone secretion

Abstract

In order to validate an association between pituitary size and severity of growth hormone deficiency (GHD) we evaluated the magnetic resonance images (MRI) of 107 children with different causes of short stature. Ninety-one MRIs were evaluable (64 male, 27 female; age: 9.1 +/- 3.9 years). The levels of insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3), and tests of GH stimulation and spontaneous secretion, led to the following subgroups: severe isolated GHD (SIGHD) (GH < 7 ng/ml) (n = 21); partial, isolated GHD (GH 7-10 ng/ml) (n = 22); multiple pituitary hormone deficiency (MPHD) (n = 13); neurosecretory dysfunction (n = 10); non-classifiable diagnosis (NC) (n = 13); idiopathic short stature (n = 9); and intra-uterine growth retardation (n = 3). Pituitary height (PHT) was measured and hypoplasia was assumed when PHT was < -2 SDS. An ectopic posterior pituitary with missing stalk and a hypoplastic anterior pituitary was present in 12 (57%) SIGHD cases, 12 (92%) MPHD cases and 1 patient from the NC group. An isolated hypoplastic anterior pituitary was observed in 15%-33% of the other groups. PHT (mm; mean, SD) in MPHD (1.7 +/- 0.5) was lower than in SIGHD (2.7 +/- 1.0, P < 0.05), with PHT of both groups being lower than in all the other groups (3.8 +/- 0.9, P < 0.0001). PHT SDS correlates with IGF-I SDS (r = 0.48, P < 0.0001), IGFBP-3 SDS (r = 0.46, P < 0.0001) and the highest peaks in tests of GH stimulation and GH spontaneous secretion (r = 0.36, P < 0.0001). In contrast to all the other groups, no correlation with age was observed in MPHD and SIGHD. Breech delivery was recorded in up to 26% of patients in all seven groups. Surprisingly, only 1 out of 23 patients with an ectopic posterior pituitary was born by breech delivery, suggesting that ectopia of the posterior lobe is not necessarily related to breech delivery.

Conclusion: PHT is significantly correlated with GH secretion in several types of short stature. Patients with ectopic posterior pituitary, missing stalk and hypoplastic anterior pituitary either suffer from SIGHD or MPHD, and this anatomical defect is not necessarily related to breech delivery.