To Örebro University

Introduction: The diagnosis of growth hormone (GH) deficiency (GHD) is complicated by the low specificity of GH testing, especially in children before and during early pubertal stages. Sex steroid priming reduces false positive results in pre- and early pubertal children. However, only a small number of studies have assessed its efficacy in improving the diagnostic accuracy of GHD investigations.

Aim: To evaluate the effect of sex steroid priming in GH testing on the prevalence of divergent results of spontaneous nocturnal secretion and arginine-insulin-tolerance test (AITT).

Methods and Materials: This is a retrospective chart review of all 196 children investigated for GHD from January 1, 1993 until February 28, 2023 at the Department of Paediatrics, Örebro University Hospital, Örebro, Sweden. Of them 173 (89%) children had undergone both overnight GH sampling and AITT and 28 of 173 children (16%) had received estrogen priming prior to their tests. A GH peak concentration of ≥ 7.0 μg/L or more was considered normal for both tests.

Results: Children receiving priming (36% girls) had a median age of 12.1 years (6.2–15.0) vs. 8.4 years (1.5 – 15.9) in children not primed (43% girls). Of the 173 children that had undergone both tests, 31 (18%) tested positive (<7.0 μg/L) on both tests, 22 (13%) tested positive on overnight sampling only, and 13 (8%) tested positive on AITT only. Of the 28 children who had received priming ,only one child had divergent results, with a positive result solely from AITT. Amongst non-primed children, 34 of 145 had divergent results with 21 (14.6%) testing positive on AITT, and 13 (9%) exhibiting a positive result on the spontaneous GH test. The frequency of divergent tests was significantly lower (p = 0.016) amongst primed children (3.6%) compared to non-primed children (23.6%).

Conclusion: Our results show that sex steroid priming prio rto GHD testing with overnight sampling and AITT decreases the frequency of divergent results between the two tests and thus suggest that sex steroid priming decreases the risk of false positive results.