ESPE Abstracts (2014) 82 P-D-2-3-437

Long-Term Effects of GH Replacement Therapy on Thyroid Function in GH Deficiency Children

Andrea Esposito, Iolanda Di Donato, Martina Rezzuto, Sara Alfano, Cristina Moracas, Donatella Capalbo & Mariacarolina Salerno

Pediatric Endocrinology Unit, Department of Translational Medical Sciences, University ‘Federico II’ of Naples, Naples, Italy

Background: Several studies have investigated the effects of GH replacement therapy (GHRT) on thyroid function in children with GH deficiency (GHD) leading to contrasting results. Indeed, GHRT has been reported to affect the peripheral metabolism of thyroid hormones, to alter TSH secretion by pituitary and to unmask secondary hypothyroidism.

Objective and hypotheses: To evaluate long-term effects of GHRT on thyroid function in a large cohort of GHD children.

Method: Sixty-five children (40M) aged 9.47±3.73 years with isolated GHD were studied before and during the first 3 years of GHRT. Clinical parameters (height, weight, BMI, and growth velocity) and serum TSH, FT4, FT3, and IGF1 levels were evaluated at baseline, after 6 months of GHRT and then annually.

Results: At study entry, all GHD children were euthyroid and none became hypothyroid during the follow-up. Six months of GHRT were associated with reduction in FT4 levels and increase in FT3 levels even though they were still normal associated with no differences in TSH concentrations. No further modifications were observed in the following years of therapy.

Table 1.
Baseline6 months1 year2 years3 years
Height (SDS)−2.73±0.82−2.42±0.73a−2.18±0.72−1.77±0.78−1.52±0.85
BMI (SDS)−0.35±1.21−0.51±1.20a−0.44±1.13−0.45±1.16−0.32±1.20
Growth velocity (SDS)−2.57±1.453.30±2.63a3.09±3.162.65±3.211.62±2.81
FT4 (ng/dl)1.20±0.221.14±0.20a1.13±0.221.14±0.211.14±0.21
FT3 (pg/ml)3.79±0.724.01±0.69a4.03±0.713.97±0.663.99±0.69
TSH (μU/ml)2.67±1.282.63±1.482.71±1.452.48±1.152.55±1.28
IGF-1 (SDS)−0.99±1.060.22±1.45a0.81±1.690.93±1.720.58±1.34

Conclusion: In GHD children GHRT was associated with a persistent decrease of FT4 concentrations which however remained within reference ranges. Whether these mild changes may have a clinical impact should be further investigated.

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