Sinha Indrajit, Ghosh Sandip, Dey Prasenjit, Jacob Jose, Banerjee Dibyajyoti
Department of Biochemistry, Kasturba Medical College, Manipal-576104, Karnataka State, India.
Clin Chim Acta. 2005 May;355(1-2):91-6. doi: 10.1016/j.cccn.2004.12.011.
Albumin is a potent antioxidant as it chelates transitional metals and contains antioxidants like thiol and bilirubin. In neprotic syndrome, the defining parameter is proteinuria with hypoalbuminemia. Therefore albuminuria in nephrotic syndrome may increase toxic transitional metal ions and also can cause loss of albumin associated antioxidants causing oxidative stress to the individual.
We investigated this possibility and estimated some markers of oxidative stress in 20 nephrotic syndrome patients and healthy controls along with urinary thiols, urinary bilirubin and plasma free iron in both cases and in the controls.
We found oxidative stress in 20 nephrotic syndrome patients and the markers of oxidative stress correlated significantly with proteinuria, but the urine of nephrotic syndrome patients (28.33+/-4.2 micromol/g creatinine)contained significantly less thiols compared to the healthy controls (88.45+/-10.6 micromol/g creatinine) and no biliribin. The patients plasma also showed free iron (0.7+/-0.05 micromol/l), a parameter undetectable in the healthy controls.
We suggest that oxidative stress and presence of free iron in the patients were responsible for less thioluria and no bilirubinuria. A detailed study of oxidative biology in a large cohort of nephrotic syndrome patients is necessary to confirm the presence of free iron as appropriate chelation of free iron may benefit the long-term prognosis of the disease.
白蛋白是一种有效的抗氧化剂，因为它能螯合过渡金属，并含有诸如硫醇和胆红素等抗氧化剂。在肾病综合征中，其决定性参数是蛋白尿伴低白蛋白血症。因此，肾病综合征中的白蛋白尿可能会增加有毒过渡金属离子，还会导致与白蛋白相关的抗氧化剂流失，从而给个体造成氧化应激。
我们研究了这种可能性，并评估了20例肾病综合征患者和健康对照者的一些氧化应激标志物，同时检测了病例组和对照组的尿硫醇、尿胆红素及血浆游离铁。
我们发现20例肾病综合征患者存在氧化应激，且氧化应激标志物与蛋白尿显著相关，但肾病综合征患者尿液中的硫醇含量（28.33±4.2微摩尔/克肌酐）明显低于健康对照者（88.45±10.6微摩尔/克肌酐），且无胆红素。患者血浆中还显示有游离铁（0.7±0.05微摩尔/升），而健康对照者中未检测到该参数。
我们认为患者体内的氧化应激和游离铁的存在是导致硫醇尿减少和无胆红素尿的原因。有必要对大量肾病综合征患者进行氧化生物学的详细研究，以确认游离铁的存在，因为对游离铁进行适当螯合可能有利于该疾病的长期预后。
