ESPE Abstracts

Objective: Children who are small for gestational age (SGA) and do not exhibit compensatory growth by the age of 4 years have been shown to benefit in their final height from growth hormone (GH) therapy. The GH-IGF1 axis stimulates physical growth, regulates metabolism and cardiovascular functions. Only one case of a child with GH deficiency presenting with atrioventricular (AV) block during GH therapy has been reported to date. Here, we describe the occurrence of third-degree AV block in an SGA child during GH therapy.

Method: A 10.5-year-old boy was referred due to delayed growth. He was born at 39 weeks with a birth weight of 2200 grams (-3.70 SD) and a birth length of 46 cm (-3.3 SD). His family history was unremarkable. Clinical examination revealed a height of 126 cm (-2.35 SD), a weight of 25 kg (-2 SD), and Tanner stage I. The rest of the clinical examination was normal. His weight and height had been below the third percentile since birth. Cardiological examination, basic hormonal and laboratory tests including celiac antibodies, pituitary MRI, and karyotype were normal. Renal ultrasound revealed a single left kidney. GH stimulation test with glucagon showed a peak GH secretion of 10.5 ng/ml. His bone age was delayed by 3 years. Since he was born SGA and had inadequate growth until at least 4 years old, hGH therapy was initiated at a dose of 0.03 mg/kg/week, resulting in a good growth rate (10-12 cm/year).

Results: After 21 months of GH therapy, a routine cardiological examination, while asymptomatic, revealed third-degree AV block, leading to discontinuation of GH therapy. No treatment for the AV block was initiated. Throughout the GH therapy, IGF-1 levels were normal, and no infection was reported. Six months after stopping the hGH therapy, a cardiological re-evaluation with Holter monitoring was performed, which showed no evidence of third-degree atrioventricular block. After extensive literature review and since this side effect is not well documented, we continued hGH treatment. He is now receiving hGH therapy and regular cardiological evaluations once every three months.

Conclusion: This case suggests that SGA children should be evaluated cardiologically both before and during hGH therapy treatment. The development of AV block in our patient, though rare, highlights the importance of continuous monitoring to detect potential cardiovascular issues. While the AV block is not necessarily caused by hGH therapy, clinicians should remain aware of this risk.