Growth hormone stimulation testing in a tertiary paediatric hospital: a review of practice

Eimear O; Eirin Carolan; Colm Costigan; Nuala Murphy

doi:10.1530/endoabs.111.P71

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Endocrine Abstracts (2025) 111 P71 | DOI: 10.1530/endoabs.111.P71

BSPED2025 Poster Presentations Pituitary and Growth (10 abstracts)

Growth hormone stimulation testing in a tertiary paediatric hospital: a review of practice

Eimear O’Connell ¹ , Eirin Carolan ¹ , Colm Costigan ¹ & Nuala Murphy ^1,2

Author affiliations

¹Department of Paediatric Endocrinology, Children’s Health Ireland at Temple Street, Dublin, Ireland; ²School of Medicine, University College Dublin, Dublin, Ireland

Background: Growth hormone deficiency (GHD) is an uncommon yet significant cause of short stature in children. There is no gold standard test for diagnosis of GHD, however growth hormone stimulation testing (GHST) remains a key diagnostic tool. Current international consensus recommends that failure to reach a peak GH of >/= 7ng/ml in two separate GHSTs is needed to confirm GHD in order to limit false positive results.

Aims: This study aimed to review the use of GHSTs in children with suspected GHD in a tertiary paediatric endocrinology unit and investigate the rate of false positive results of a single GHST based on subsequent clinical diagnosis of GHD.

Methods: This was a retrospective observational study of children who underwent GHST between January 2022 and December 2023 at Children’s Health Ireland (CHI), Temple Street. Data were retrieved from the endocrine nurse database, clinic letters, radiology, and laboratory systems. Age, sex, medical history, auxological measurements, IGF-I, IGF-BP3, GHST results and bone age determination were recorded. Peak GH values on GHSTs and subsequent diagnosis or exclusion of GHD were recorded for each child and the false positive rate of a single GHST was calculated. The sensitivity and specificity of IGF-I and IGF-BP3 as diagnostic markers were calculated.

Results: Out of 73 children (75% male) tested, 46% were diagnosed with GHD following one (n = 12) or two (n = 22) GHSTs. Eleven of the 12 children diagnosed following one test had a very poor GH response (<3ng/ml) and a known structural pituitary anomaly. The false positive rate of a single GHST was 33% using a threshold of <7ng/ml and 23% using a threshold of <5.5ng/ml. The majority of false positive results occurred in peripubertal boys. IGF-I was found to have a sensitivity of 54% and specificity of 47%, while IGF-BP3 demonstrated high specificity of 100% but very low sensitivity of 12.5%.

Conclusion: This study highlights the importance of clinical judgement in the diagnosis of GHD. Due to high false positive rates of a single GHST, two tests should be conducted where possible, in particular for suspected Idiopathic-isolated GHD. Sex hormone priming should be considered for all peripubertal children.