ESPE Abstracts

Background/Aim: Although there are many well-known components that affect the growth response to recombinant growth hormone (rGH), its effect on total height gain is still not fully predictable. A limited number of studies have been reported revealing up-to-date data on the relationship between immunogenicity and growth-promoting effects of rGH. The study aimed to examine the antibody formation against rGH and its consequences on growth-promoting effect in children with short stature.

Materials and Methods: This was a cross-sectional study including 193 children treated with rGH therapy. The participants were classified into three groups, 111 of whom diagnosed with growth hormone deficiency (GHD), 37 idiopathic short stature (ISS), and 45 short stature due to non-endocrine disorders. The number of the participants based on years of treatment was as follows: 24, 34, 46, 39, 21, 29 children; at onset, first, second, third, 4^th, and ≥5^th years on treatment. The GH antibody (GH-Ab) and total IgE assays were studied from 193 and 97 participants, respectively. The frequency of GH-Ab, and association of rGH immunogenicity with growth response were evaluated in the three groups.

Results: The number of GH-Ab- and total IgE-positive patients were 103 (53.3%) and 25 (25.7%), respectively. The GH-Ab-positive patients were more common in the ISS group (67.5%) (P = 0.013). The number of GH-Ab-positive patients was 15 of 24 (62.5%) patients whose test was studied before treatment. The means of first-year height velocity were found to be lower in the GH-Ab-positive than in the GH-Ab-negative patients in the three groups, (GHD; 8.62±2.97cm/year vs. 10.91±3.63cm/year, ISS; 5.63±0.11cm/year vs. 8.30±1.79cm/year, non-endocrine; 7.75±1.26cm/year vs. 10.12±2.26cm/year; P = 0.003, P = 0.003, and P = 0.001, respectively). Similarly, the means of first-year height velocity were found to be lower in IgE-positive patients (7.01±3.25cm/year vs. 8.93±2.16cm/year; p = 0.032). The first-year height velocity was negatively correlated with GH-Ab and total IgE levels in the non-endocrine group, (r = -0.468, P = 0.039; r=-0.448, P = 0.042, respectively)

Conclusion: This study showed that GH-Ab formation is common in children with short stature, especially those with ISS before and during rGH treatment, and also GH-Ab positivity is associated with lower first-year height velocity. In addition, this indicates that GH-Abs both could play a role in the aetiology of GH-related short stature, and that immunogenicity against rGH could have an impact on first-year height velocity.