Comparison of the efficacy of GH therapy in short children with decreased nocturnal GH secretion and either normal or subnormal results of GH stimulating tests
Maciej Hilczer1,2, Joanna Smyczynska1,2, Renata Stawerska1,2 & Andrzej Lewinski2,3
Indications to GH therapy in children with short stature are still a matter of discussion.
We compared first-year response to GH therapy in 80 children (62 boys, 18 girls), age 12.7±2.4 years (mean±S.D.) with different disorders of GH secretion. In all the patients nocturnal GH secretion assessed during 3 h after falling asleep was decreased (<10 ng/ml). In 40 children GH deficiency (GHD) was diagnosed on the ground of decreased GH secretion (<10 ng/ml) in 2 standard stimulating tests (with clonidine and glucagon). In other 40 age-matched children the results of GH stimulating tests were normal but IGF1 secretion was decreased and neurosecretory dysfunction of GH secretion (NSD) was diagnosed. All the children were treated with GH in a dose of 0.21±0.02 mg/kg per week. Patients height velocity (HV), IGF1 secretion and its bioavailability (IGF1/IGFBP-3 molar ratio) were assessed before and after 1 year of GH therapy.
Before treatment height SDS was −2.97±0.72 in GHD and −2.99±0.64 in NSD, HV was 3.5±0.8 cm/year and 3.6±0.9 cm/year, IGF1 SDS for age and sex was −1.98±1.07 and −2.30±1.02, IGF1/IGFBP-3 molar ratio was 0.20±0.09 and 0.18±0.06, respectively. After 1 year of GH therapy, HV increased to 9.9±2.1 cm/year in GHD and 9.6±1.8 cm/year in NSD group, IGF1 SDS for age and sex was 0.65±0.86 and 0.47±0.93, IGF1/IGFBP-3 molar ratio was 0.43±0.13 and 0.41±0.15, respectively. There were no significant differences in any of the analysed auxological parameters and in IGF1 secretion between the children with GHD and NSD, both before and after 1 year of GH administration. An increase of all the analysed indices in both groups was similar and significant (P<0.001).
The response to GH therapy in children with decreased nocturnal GH secretion and either subnormal or normal results of GH stimulating tests was similar. It seems that in children with decreased nocturnal GH secretion and decreased IGF1 concentration the indications to GH therapy should not depend on the results of GH stimulating tests only, however, further observation up to final height is necessary to confirm this preliminary conclusion.