胰島素生長因子Ⅰ檢測試劑盒（酶聯(lián)免疫法）產(chǎn)品說明:

【產(chǎn)品名稱】

通用名稱：胰島素生長因子Ⅰ檢測試劑盒（酶聯(lián)免疫法）

英文名稱：IGF-I ELISA

【預(yù)期用途】

用于定量測定人血清和血漿中人胰島素樣生長因子 I (IGF-I) ，僅供科研使用。

【包裝規(guī)格】

96人份/盒

【背景知識(shí)】

胰島素樣生長因子 (IGF)-l 和 -ll 在許多細(xì)胞類型的增殖、分化和特定功能的調(diào)節(jié)中發(fā)揮關(guān)鍵作用 (1-3)。IGF-/ 與 somatomedin c (Sm-C) 相同(4) 分子量為 7649 道爾頓 (5). 它的主要調(diào)節(jié)劑是生長激素 (GH) 和營養(yǎng) (6)，盡管它在特定組織中的合成受多種熱帶激素和其他肽生長因子的影響。與許多其他肽激素相比，IGF 以高親和力與特異性結(jié)合蛋白 (IGFBP) 結(jié)合。目前已知有七類結(jié)合蛋白 (7,8,22)。它們要么以相似的親和力結(jié)合 IGF-I 和 IGF-II，要么表現(xiàn)出對(duì) IGF-II 的偏好 (9,10)。測量 IGF-I 的一個(gè)主要問題是在測定中干擾 iGFBPs。在未經(jīng)處理的血清樣品中直接測定 (11) 會(huì)導(dǎo)致不正確的結(jié)果，因?yàn)橛捎谠跍y定孵育期間 IGF-IIGFBP-3 復(fù)合物的解離極慢，因此只有部分 IGF-1 可用于測量。根據(jù)樣品中 IGF 與 IGFBP 的比例，會(huì)發(fā)生干擾：（參見圖 1 中的示例）

因此，人們開發(fā)了多種方法在實(shí)際測量前將 IGF-I 從其結(jié)合蛋白中分離出來：(a) 酸性條件下的尺寸排阻色譜法，(b) 固相萃取和 (c) 酸-醇萃取(2,12,13) ）。然而，這些方法要么費(fèi)時(shí)費(fèi)力，要么導(dǎo)致不完全，尤其是不可重現(xiàn)的回收。最普遍的方法是酸-醇萃取 (13,14)。然而，由于共沉淀，它僅產(chǎn)生 70-80% 的結(jié)合 IGF-I。因此，在這樣的提取步驟之后測量的絕對(duì)值非常低（15）。提取過程導(dǎo)致樣品的預(yù)稀釋，從而降低了測定的靈敏度。此外，提取僅不足以去除 IGFBP。提取物中殘留的 IGFBP 仍會(huì)干擾檢測。除血清或血漿外，酸-酒精提取在其他樣品（例如細(xì)胞培養(yǎng)基）中完全無效。正是在這里，IGF-1 的測定特別困難，因?yàn)檫@些樣品通常含有大量過量的 IGFBP。

【臨床意義】

除了 GH，還有許多因素影響血清 IGF-I 水平。在營養(yǎng)不良/吸收不良、甲狀腺功能減退、肝病、未經(jīng)治療的糖尿病、慢性炎癥性疾病 (1,6)、惡性腫瘤或多發(fā)性創(chuàng)傷中發(fā)現(xiàn)水平降低。高水平可在性早熟或肥胖中發(fā)現(xiàn)的。對(duì)于 IGF-I 測定的正確解釋至關(guān)重要的是要考慮 IGF-I 水平的年齡依賴性（年齡依賴性參考值見表 2 和圖 4-6） .

由于其 GH 依賴性，血清 IGF-1 的測定對(duì)于診斷生長障礙具有重要價(jià)值，特別是對(duì)于 GH 缺乏或肢端肥大癥 (6,16-19,23,24)。與 GH 測定相比，IGF-J 測定最重要的優(yōu)點(diǎn)是其穩(wěn)定的晝夜?jié)舛龋匆淮螠y量就足以提供信息。因此，IGF-1 測定應(yīng)成為實(shí)驗(yàn)室診斷的重中之重。顯然，正常水平排除了 GH-IGF-1 軸的紊亂。低水平，即接近或低于與年齡相關(guān)的第 5 個(gè)百分位的水平，需要進(jìn)一步的診斷步驟。如果排除其他導(dǎo)致低血清 IGF-I 的原因（如營養(yǎng)不良或肝功能受損），則 IGF-I 水平低于正常水平可能是 GH 分泌受損的跡象。區(qū)分健康、身材矮小、非 GH 缺乏的兒童和患有“經(jīng)典的“生長激素缺乏癥”，已發(fā)現(xiàn) 0.1 個(gè)百分位數(shù)是一個(gè)很好的分界點(diǎn)，尤其是從 8 歲開始。然而，必須注意的是，沒有生長激素缺乏癥的身材矮小兒童的分?jǐn)?shù)很可能在 0.1 和 5 個(gè)百分位數(shù)之間(19) 相比之下，肢端肥大癥的特征是病理性升高的 IGF-I 水平，這似乎比 GH 測量值更能反映疾病嚴(yán)重程度 (17,18,20)。

【參考文獻(xiàn)】

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11. Furlanetto RW,Underwood LE,Van Wyk JJ, DErcole AJ.1977 Estimation of somatomedin-C levels in normals and patients with pituitary disease by radioimmunoassay.J. Clin lnvest.60:648-657.

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15. Ranke MB(ed.);: Diagnostics of Endocrine Function in Children and Adolescents,basel,Karger, 2003,pp 166-199

16. Rosenfeld RG,Wilson DM, Lee PDK, Hintz RL.1986 Insulin-like growth factors l and ll in evaluation of growth retardation.J Pediatr. 109:428-433.

17. Clemmons DR, Van-Wyk JJ, Ridgway EC,Kliman B,Kjellberg RN,Underwood LE.1979 evaluation of acromegaly by radioimmunoassay of somatomedin-C.N.Engl J Med.

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18. Zapf J, Walter H, Froesch ER.1981 Radioimmunological determination of insulin-like growth factors land ll in normal subjects and in patients with growth disorders andextrapancreatic tumor hypoglycemia.J Clin Invest.68:1321-1330.

19. Blum WF.1992 Insulin-like growth factors and their binding proteins. In: Ranke MB, ed.Functional Endocrinologic Diagnostics in Children and Adolescence.Mannheim:J+JVerlag; 102-117.

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22. Wilson EM, Oh Y, Rosenfeld RG (1997) Generation and characterization of an IGFBP-7 antibody: ldentification of 31 kD IGFBP-7 in human biological fluids and Hs578T humanbreast cancer conditioned media.J Clin Endocrinol metab Vol 82,4:1301-1303

22. Ranke MB, Schweizer R, Elmlinger MWw, Weber K, Binder G, Schwarze CP, Wollmann HA(2000)Significance of basal IGF-l,IGFBP-3 and IGFBP-2 measurements in thediagnostics of short stature in children. Horm Res 54:60-68

23. Ranke MB, Schweizer R, Elmlinger Mw, Weber K, Binder G, Schwarze CP, Wollmann HA(2001) Relevance of lGF-I, IGFBP-3 and lGFBP-2 measurements during GH treatment of GH-deficient and non-GH-deficient children and adolescents.Horm Res55:155-124

24. Address NIBSC: Blance Lane, South Mimms, Potters Bar, Hertford EN 6 3 QG, Great Britain

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27. Ranke MB,Osterziel KJ, Schweitzer R, Schuett B., Weber K., Robbel P, Vornwald A,Blumenstock G, EImlinger MB (2003)Reference Levels of lnsulin-Like-Growth Factor l inthe Serum of Healthy Adults: Comparison of Four lmmunoassays.Clin Chem Lab MedVol41(10):1329-1334