Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
Horm Metab Res. 2012 Nov;44(12):900-3. doi: 10.1055/s-0032-1314855. Epub 2012 Jun 6.
Growth hormone (GH) values vary among immunoassays depending on different factors, such as the assay method used, specificity of antibodies, matrix difference between standards and samples, and interference with endogenous GH binding proteins (GHBPs). We evaluated whether the use of different calibrators for GH measurement may affect GH values and, consequently, the formulation of GH deficiency (GHD) diagnosis in children. Twenty-three short children (5 F, 18 M; age 11.4±3.1 years), with the clinical characteristics of GHD (height: -2.3±0.5 SDS; height velocity -2.3±1.5 SDS; IGF-I -1.2±0.9 SDS), underwent GH stimulation tests to confirm the clinical diagnosis of GHD. Serum GH values were measured with Immulite 2000, using 2 different calibrators, IS 98/574, a recombinant 22 kDa molecule of more than 95% purity, and IS 80/505, of pituitary origin and resembling a variety of GH isoforms. We found blunted GH secretion in 20 subjects with the Immulite assay using the IS 98/574 GH as a calibrator, confirming the diagnosis of GHD. Subsequently, using IS 80/505 GH as a calibrator, in the same samples only 14 children showed reduced GH levels. The total cost for the first year of GH therapy of patients diagnosed with IS 98/574 as a calibrator was higher than that for patients diagnosed with IS 80/505 as a calibrator. These data confirm that GH values may depend on different calibrators used in the GH assay, affecting the formulation of GHD diagnosis and the consequent decision to start GH treatment.
生长激素（GH）值在不同的免疫分析中因不同的因素而有所差异，例如所使用的分析方法、抗体的特异性、标准品和样品之间的基质差异以及与内源性 GH 结合蛋白（GHBPs）的干扰。我们评估了使用不同校准品进行 GH 测量是否会影响 GH 值，并因此影响儿童 GH 缺乏症（GHD）诊断的制定。23 名身材矮小的儿童（5 名女性，18 名男性；年龄 11.4±3.1 岁），具有 GHD 的临床特征（身高：-2.3±0.5 SDS；身高增长率：-2.3±1.5 SDS；IGF-I：-1.2±0.9 SDS），进行了 GH 刺激试验以确认 GHD 的临床诊断。使用 Immulite 2000 测量血清 GH 值，使用 2 种不同的校准品，IS 98/574，一种超过 95%纯度的 22kDa 重组分子，和源自垂体的 IS 80/505，类似于多种 GH 同工型。我们发现，使用 Immulite 测定法和 IS 98/574 GH 作为校准品时，20 名受试者的 GH 分泌受到抑制，证实了 GHD 的诊断。随后，在同一批样本中，使用 IS 80/505 GH 作为校准品时，只有 14 名儿童的 GH 水平降低。使用 IS 98/574 作为校准品诊断的患者第一年 GH 治疗的总费用高于使用 IS 80/505 作为校准品诊断的患者。这些数据证实，GH 值可能取决于 GH 测定中使用的不同校准品，从而影响 GHD 诊断的制定以及随后开始 GH 治疗的决定。
