Thyroid function during the first year of recombinant human growth hormone therapy in short stature children.

Introduction: The relationship between rhGH treatment and thyroid function has been the subject of numerous studies. Some say that rhGH treatment unmasks central hypothyroidism, other say that rhGH induces subclinical primary hypothyroidism.

Aim: To assess the changes in thyroid function in short stature children in the first year of treatment with rhGH and the impact on growth velocity.

Material And Methods: We evaluated 37 patients treated with rhGH, 5 were excluded because developed side effects during treatment. We measured height, height velocity, and height standard deviation gain during treatment and thyroid function during the first year of treatment.

Results: We observed a slight increase in the TSH level and no significant change in the f T4 level after the first 3-6 months of treatment in all the groups; in GH deficiency (GHD) patients, we observed a statistically significant decrease of the f T4 level after the first 3-6 months, without a significant increase of the TSH level. After the first year, thyroid function returned to baseline. There were no differences between height velocities in all the groups, except from the GHD patients.

Conclusions: The slight increase in the TSH level and the decrease of f T4 level might unmask a transient subclinical primary hypothyroidism but these changes do not influence the growth velocity in first year of rhGH treatment.