Evaluation of growth hormone stimulation testing in children

Abstract

Objective: To evaluate the use and interpretation of growth hormone (GH) stimulation tests used across the UK for diagnosing GH deficiency.

Background: Previous studies show poor consensus on the use of GH stimulation tests. Sex steroid priming and retesting in the transition period are areas not previously surveyed.

Design: Data were collected from tertiary paediatric endocrinologists, paediatricians with a specialist interest in endocrinology and biochemists across the UK over 6 months through distributing electronic surveys.

Results: At least three different GH stimulation tests were used by 33% of departments. Glucagon and insulin doses varied most, and sampling frequency varied most using insulin. All laboratories use a recommended chemiluminescence immunoassay with an acceptable coefficient of variability. The GH peak for diagnosing GH deficiency varied from 6 to 8 μg/l. A wide range of clinical scenarios prompted retesting in the transition period, suggesting nonstandardized current practice. Seventy-five per cent of departments use sex steroid priming, but follow criteria variously combining bone age, chronological age and pubertal stage, together with variations in steroid type and dose.

Conclusions: Although a contentious diagnostic test, GH stimulation tests remain the gold standard for diagnosing GH deficiency. Our data suggest that together with variation in indication, protocol and interpretation, there is considerable variation in current practices pertaining to priming and retesting in transition. Given the current financial climate and the need for careful resource management, this study emphasizes the considerable need for consensus in the investigation, diagnosis and long-term follow-up of these children, at least nationally if not internationally.