Kepka Alina, Dariusz Szajda Sławomir, Stypułkowska Anna, Waszkiewicz Napoleon, Jankowska Anna, Chojnowska Sylwia, Zwierz Krzysztof
Department of Laboratory Diagnostics of the Institute "Pomnik-Centrum Zdrowia Dziecka", Warsaw, Poland.
Clin Chem Lab Med. 2008;46(6):831-5. doi: 10.1515/CCLM.2008.171.
Disturbances in the function of renal proximal tubules increase the activity of several enzymes in urine. Among them is fructose-1,6-bisphosphatase (FBP-1), the key enzyme of gluconeogenesis normally present in the renal convoluted, and to smaller degree, proximal renal tubular cells cytosol. FBP-1 activity in urine and serum was used for evaluation of the degree of graft ischemia during human kidney transplantation. The aim of our present research was to determine FBP-1 activity in urine as an indicator of damage to renal proximal tubules in children with idiopathic nephrotic syndrome (INS).
We evaluated the excretion of FBP-1 into urine of 21 children (10 girls and 11 boys) with INS, aged from 10 to 15 years and 30 healthy children (14 girls and 16 boys), aged from 2 to 15 years. FBP-1 activity was determined by the Latzko and Gibbs method. Creatinine (mg%) in urine and blood serum was measured by the Jaffe method in Larsen modification. Protein in blood serum was determined by the biuret method (g/L), and albumin (mg%) by the Young method. Proteinuria in the urine collected over 24 h was measured with the Exton turbidimetric method by Tomaszewski with modification and expressed in mg/kg body weight/24 h.
In the urine of 30 healthy children, FBP-1 activity was in the range from 0-1.74 micromol FPB/h/mmol of creatinine. In 43% of the healthy children, FBP-1 activity in urine was not detectable. In the period of intensive proteinuria during the INS in children, FBP-1 activity and protein concentrations in urine were significantly higher than in the control group (p<0.0008 and p<0.0001, respectively). In the urine of children with active INS, we observed a very weak negative linear correlation between protein concentration and FBP-1 activity (r=-0.5018, p=0.067). After treatment with Encorton (prednisone), FBP-1 activity and protein concentration in urine dropped to values of the control group.
"The overload" of proximal renal tubules by proteins in children with INS releases FBP-1 into urine. FBP-1 activity in urine may therefore be considered as a marker of damage to the proximal renal tubules in children with INS.
肾近端小管功能紊乱会增加尿液中几种酶的活性。其中包括果糖-1,6-二磷酸酶（FBP-1），它是糖异生的关键酶，正常存在于肾曲小管，在近端肾小管细胞胞质溶胶中的含量较少。尿液和血清中的FBP-1活性用于评估人类肾移植过程中移植物缺血的程度。我们当前研究的目的是确定尿液中FBP-1的活性，作为特发性肾病综合征（INS）患儿肾近端小管损伤的指标。
我们评估了21名年龄在10至15岁的INS患儿（10名女孩和11名男孩）以及30名年龄在2至15岁的健康儿童（14名女孩和16名男孩）尿液中FBP-1的排泄情况。FBP-1活性采用拉茨科和吉布斯方法测定。尿液和血清中的肌酐（mg%）采用经拉森改良的雅费法测定。血清中的蛋白质采用双缩脲法（g/L）测定，白蛋白（mg%）采用扬法测定。24小时收集尿液中的蛋白尿采用经托马谢夫斯基改良的埃克斯顿比浊法测定，并以mg/kg体重/24小时表示。
在30名健康儿童的尿液中，FBP-1活性范围为0 - 1.74微摩尔FPB/小时/毫摩尔肌酐。43%的健康儿童尿液中未检测到FBP-1活性。在儿童INS的大量蛋白尿期，尿液中FBP-1活性和蛋白质浓度显著高于对照组（分别为p<0.0008和p<0.0001）。在患有活动性INS的儿童尿液中，我们观察到蛋白质浓度与FBP-1活性之间存在非常弱的负线性相关性（r = -0.5018，p = 0.067）。用强的松治疗后，尿液中FBP-1活性和蛋白质浓度降至对照组水平。
INS患儿肾近端小管被蛋白质“过载”会使FBP-1释放到尿液中。因此，尿液中FBP-1活性可被视为INS患儿肾近端小管损伤的标志物。
