서론 저신장은 하나의 질환이기보다는 다양한 원인으로 발생하는 현상으로 신장이 같은 연령, 같은 성별의 평균 신장보다 3백 분위수 미만일 경우 또는 -2.0 SD (표준편차)보다 작은 경우 를 말한다[1,2]. 임상에서는 저신장증의 원인을 찾기 위해 가 족력, 성장환경, 영양상태, 선천성대사이상질환 유무 등을 알 아보고, 성장호르몬 관련 검사, 갑상샘호르몬검사, 유전자검 사 등의 진단적 검사를 시행한다. 그 중 성장호르몬은 뇌하수 체에서 박동성으로 분비되기 때문에 한번 측정한 검사결과는 의미가 없으며 24시간 동안 일정 간격으로 채혈하여 그 농도 를 검사하거나 2가지 이상의 약물을 통한 유발검사를 시행한 다[3,4]. 그러나 성장호르몬자극검사의 번거로운 과정과 자연 적인 생체 내의 성장호르몬 분비를 반영하지 못한다는 점 등으 로 인하여, 일중 변동이 거의 없고 내인성 성장호르몬 분비상 태를 잘 반영하는 인슐린양 성장인자 I (insuline like growth factor-I,

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... F-I)과 인슐린양 성장인자 결합단백-3 (insulin like growth factor binding protein-3, IGFBP-3)이 성장호르 몬 결핍증의 진단에 유용한 선별검사로 이용되고 있다[5,6]. 하지만 이 두 검사에 대한 민감도와 특이도가 보고자마다 달라 Background: Serum insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) levels are known markers of growth hormone (GH) secretion. The clinical utility of serum IGF-I and IGFBP-3 testing, however, remains controversial. The aims of this study were to evaluate the usefulness of IGF-I and IGFBP-3 as indicators of GH secretion through the GH stimulation test and to investigate whether a decrease in serum IGF-I levels in children with short stature, regardless of the cause, can be used as a screening test for short stature. Methods: A total of 262 children presented with short stature, precocious puberty, or premature thelarche and were grouped into 7 tiers based on the 2007 growth chart. Serum IGF-I and IGFBP-3 levels and GH stimulation were analyzed using an immunoradiometric assay, and the data from 68 children who were below the 3rd percentile for height were used to evaluate the usefulness of IGF-I and IGFBP-3 as markers of GH status. Results: GH deficiency was confirmed by the GH stimulation test in 25 of the 68 children, and 15 (15/25, 60%) and 4 (4/25, 16%) of them showed a decrease in IGF-I and IGFBP-3 levels, respectively. The sensitivity and specificity for predicting GH secretion were 60% and 16%, respectively, for IGF-1 and 41.9% and 97.7%, respectively, for IGFBP-3. Decreased serum IGF-I levels were more frequently observed in children below the 25th percentile than in those in the 25th to 95th percentiles. Conclusions: IGF-I and IGFBP-3 levels have been used as a screening tool for GH secretion in children with short stature, but based on the results of the GH stimulation test in the current study, the levels of IGF-I and IGFBP-3 might not be useful as markers of GH secretion. Evaluating serum IGF-I levels alone is not a sufficient screening test for children with a short stature. (J Lab Med Qual Assur 2014;36:48-53)