ASSESSMENT OF GROWTH HORMONE PITUITARY RESERVE AND MAGNETIC RESONANCE IMAGING FINDINGS IN SHORT CHILDREN

Abstract

Growth hormone (GH) pituitary reserve and magnetic resonance imaging (MRI) findings were studied in 22 short prepubertal slow growing children (aged 6-11 yrs; males 14). We assessed GH responses to a combined administration of arginine (0.5g/kg) plus GH-releasing hormone (GHRH, 1μg/kg) (Arg+GHRH test) and mean spontaneous nocturnal GH secretion (MGHC, normal = >3 ng/ml). Subjects were divided into 3 groups, comparable in ages, heights and growth rates: group I, 5 GH deficient children, with reduced GH pituitary reserve (Arg+GHRH GH peaks: 20 ng/ml; 58.3±7.9 ng/ml) and low MGHC (1.9±0.3 ng/ml); group III, 8 slow growing children, with normal GH pituitary reserve (Arg+GHRH peak: 51.1±13.2 ng/ml) and normal MGHC (5.4±0.8 ng/ml). MRI examination was performed to measure height, width, lenght and volumes of the pituitary gland. Results. All children showed a normal pituitary anatomy without stalk interruption; mean gland measurements were not significantly different between the 3 groups (height: 2.7±0.5, 3.5±0.3, 3.1±0.3 mm in groups I, II, III, respectively; volumes: 111.6 ± 32, 124.5 ± 15 and 126.3 ± 20 mm3, respectively). These data show that in subjects with normal pituitary anatomy and intact stalk the GH pituitary reserve is not correlated with magnetic resonance imaging findings.