Fanos V, Mussap M, Plebani M, Cataldi L
Clinica Pediatrica, Università degli Studi, Verona.
Minerva Pediatr. 1999 May;51(5):167-77.
Cystatin C is a small basic protein with a MW of 13,359 Daltons, consisting of a non-glycosylated polypeptide chain containing 120 amino-acid residues. Cystatin C is produced in all the nucleated cells of the human body and its output rate is constant. The kidney is the main catabolic site of cystatin C, since the protein, by virtue of its low MW and its positive charge at normal pH, is freely filtered by the glomerulus and almost completely reabsorbed, catabolised and broken down in the cells of the proximal convoluted tubule. It is practically entirely filtered via the glomerular membrane, without any significant tubular secretion. The constant production rate of cystatin C in all the tissues, its elimination via the glomerular filter and its non-dependence on many extrinsic factors, including sex, age, diet, inflammation, are potentially ideal conditions for an endogenous biochemical marker of glomerular filtration. A recent method for determining cystatin C, is based on an immune reaction, could increase its clinical application. Not many studies have been conducted to date on cystatin C in children. The cystatin C concentration was higher during the first few days of life (range: 1.64-2.59 mg/L) with a rapid reduction during the first 4 months. Beyond the first year of life, cystatin C concentration became constant, with a reference range of 0.7-1.38 mg/L. On the basis of the data currently available, neonatal serum cystatin C would appear to derive from the newborn itself. In fact no correlations were found between maternal and neonatal serum cystatin C values. Cystatin C determination appears to be at least equivalent to serum creatinine measurement for the assessment of glomerular filtration rate in children. Further extended studies are needed to investigate these aspects more thoroughly in neonates.
胱抑素C是一种分子量为13359道尔顿的小分子碱性蛋白质，由一条含有120个氨基酸残基的非糖基化多肽链组成。胱抑素C在人体所有有核细胞中产生，其生成速率恒定。肾脏是胱抑素C的主要分解代谢部位，因为该蛋白质由于其低分子量以及在正常pH值下带正电荷，可被肾小球自由滤过，并几乎在近端曲管细胞中被完全重吸收、分解代谢和降解。它几乎完全通过肾小球膜滤过，没有任何明显的肾小管分泌。胱抑素C在所有组织中的生成速率恒定，通过肾小球滤过清除，且不依赖于包括性别、年龄、饮食、炎症在内的许多外在因素，这些潜在地是肾小球滤过内源性生化标志物的理想条件。一种基于免疫反应的测定胱抑素C的最新方法可能会增加其临床应用。迄今为止，针对儿童胱抑素C的研究并不多。胱抑素C浓度在出生后的头几天较高（范围：1.64 - 2.59mg/L），在头4个月内迅速下降。1岁以后，胱抑素C浓度变得恒定，参考范围为0.7 - 1.38mg/L。根据目前可得的数据，新生儿血清胱抑素C似乎源自新生儿自身。事实上，未发现母体和新生儿血清胱抑素C值之间存在相关性。对于评估儿童肾小球滤过率，胱抑素C测定似乎至少等同于血清肌酐测量。需要进一步开展更广泛的研究，以便更全面地调查新生儿的这些方面。
