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Journal Article 2012; 33(1): 37-41 PubMed PMID: 22467110 Citation  Keywords:  Child, Growth Disorders, Growth Hormone, Human Growth Hormone:deficiency, Humans, Insulin-Like Growth Factor I:secretion, Sleep,.   

OBJECTIVE: Growth hormone (GH) secretion is characterized by a pulsatile, circadian rhythm, with the highest concentrations at night hours. Evaluation of nocturnal GH secretion may be truncated to 6 hours. Growth hormone stimulating tests are the standard method of assessment of GH secretion. In Poland, the assessment of GH peak during 2 hours after falling asleep was introduced as a screening procedure in children, suspected for GH deficiency. The aim of current study was to compare the results of a screening test with GH secretion during 6-hour nocturnal profile and with the results of GH stimulating tests, as well as with IGF-I secretion in children with short stature.

METHODS: In 72 short children, GH concentrations were measured every 30 minutes during first 6 hours after falling asleep and in two GH stimulating tests (the cut-off level of GH peak for all the tests was 10.0 ng/ml). Also, IGF-I concentrations were measured and expressed as IGF-I SDS for age and sex.

RESULTS: The screening test results correlated significantly with both GH peak in 6-hour profile and mean GH concentration, and the area under the curve (AUC) in 6 hour profile (r= 0.94, r=0.90 and r=0.89, respectively, p<0.05) but not with GH peak in stimulating tests (r=0.07, NS). There was no correlation between IGF-I secretion and any of the analyzed parameters of spontaneous and stimulated GH secretion.

CONCLUSIONS: The results of screening test seem to reflect overnight GH secretion in short children, remaining, however, discordant with the results of GH stimulating tests and with IGF-I secretion....

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