Normal pituitary size in two patients with growth hormone gene deletion.

Somatotrope cells account for almost 50% of the volume of the pituitary gland, which is usually hypoplastic in subjects with growth hormone (GH) deficiency. Magnetic resonance imaging (MRI) was used to describe the sellar area of two siblings affected by GH gene deletion and hence absent GH secretion. Pituitary size and shape were normal in both subjects and there were no other abnormal findings in the sellar area. In particular, pituitary height (5.6 and 5.1 mm) and volume (268 and 229 mm3) in the two patients were within the normal range for age and higher than the usually reported values in GH deficient subjects. Our results suggest that the amount of GH secreted from the pituitary may have little influence on the dimensions of the gland.