Background: Administration of recombinant GH (rhGH) to GH-deficient children has yielded conflicting results concerning its impact on thyroid function. Data about patients developing subclinical hypothyroidism are scanty, but it is thought to be associated with impairment of metabolic profile and lower growth response.
Objective: To investigate the frequency of SH in children with pituitary dwarfism treated with rhGH, as well as its influence on rhGH therapy effectiveness.
Method: We reviewed the cases of 42 children (29 boys, 13 girls, aged between 4 and 14) with GH deficiency, who were qualified to rhGH therapy and treated for at least 1 year. Clinical and hormonal data (IGF1, TSH, and fT4), as well as radiographic bone assessments were documented at the beginning and after first year of rhGH treatment.
Results: At therapy onset, all patients had the height below the −2.5 S.D. (mean S.D. of −3.2), bone age was delayed, IGF1 concentration was either decreased or close to lower limit of normal range and there was no impairment in thyroid function. After one year of rhGH therapy, SH was the only impairment in thyroid function and it was diagnosed in 6 patients (16.6% of cases). Despite similar IGF1 secretion increase, the improvement of height velocity was significantly lower in children with SH (0.65 cm/month) than in those who remained euthyroid (0.88 cm/month, P<0.05). Furthermore, an increase in IGF1 levels was associated with increasing levels of TSH in SH patients and led in two cases to administration of L-T4 substitution.
Conclusion: The incidence of subclinical hypothyroidism during the initial phase of rhGH treatment in children with pituitary dwarfism and on the growth rate should be taken into account, as it may worsen the growth response and may be worsened by the rhGH therapy.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology