Background: The occurrence of antidrug antibodies is common
in children treated with recombinant human growth
hormone (rhGH). However, their clinical significance is unclear.
Objective: This study aimed to examine the clinical significance
of anti-GH antibodies by analyzing the phenotype
of patients who tested positive in relation to the quantity of
anti-GH antibodies. Method: In this laboratory-based retrospective
study encompassing a time span of 6 years, all positive
samples were identified, and senders were contacted.
Anti-GH antibodies were measured using a radioprecipitation
assay; positive samples underwent a confirmatory assay.
Results: Out of a total of 104 samples from 66 patients,
positive test results were found in 28 samples from 13 patients.
Clinical data were available from all but one. The
group with positive test results comprised 6 patients with a
normal response to GH provocative tests (group A) and 6
with an insufficient response or with isolated GH deficiency
(IGHD) type 1A (group B). Diagnoses in group A were neurosecretory
dysfunction, bioinactive GH syndrome and constitutional
delay of growth and puberty. Diagnoses in group B
were IGHD type 1A, septo-optic dysplasia, and cerebral midline
defect with multiple pituitary hormone deficiency. Insufficient
growth response to rhGH was absent except in one
sibling pair with IGHD type 1A and a patient with cerebral
midline defect. These patients had the highest concentrations
of anti-GH antibodies. Conclusions: The biological significance
of anti-GH antibodies seems to be limited to patients
with high concentrations of anti-GH antibodies. For all
other patients, we recommend a careful “wait and see” strategy
and monitoring antibody titers