测定血清IgA1半乳糖水平对诊断IgA肾病的价值

The value of detection of galactose level of serum lgA1 in diagnosis of IgA nephropathy

目的：了解IgA肾病患者血清IgA1半乳糖水平,探索其对于诊断IgA肾病的临床价值.方法：2007年5月至2008年2月在中山大学附属第一医院确诊为IgA肾病的29例患者纳入IgA肾病组,根据临床表现分成孤立性血尿组（n=14）,非孤立性血尿组（n=15）,按照Lee病理分级分成3组,分别为,Ⅰ级＋Ⅱ级组（n=9）,Ⅲ级组（n=9）,Ⅳ级＋Ⅴ级组（n=11）.同期本院门诊健康体检者18例纳入正常对照组.同期本院儿科非IgA肾病及过敏性紫癜肾炎的其他肾脏病患者18例纳入疾病对照组.3组受试者年龄、性别构成比较,差异无统计学意义（P＞0.05）.用蚕豆凝集素（vicia villosa lectin,VVL）亲和ELISA法测定IgA1与VVL的结合力,间接反映IgA1半乳糖水平,分析血清IgA1半乳糖水平对于诊断IgA肾病的临床价值.结果：IgA肾病组血清IgA1与VVL结合力 [（0.34±0.1）U]高于正常对照组[（0.27±0.06）U]及疾病对照组[（0.28±0.07）U],差异有显著性（P＜0.05）.IgA肾病非孤立性血尿组血清IgA1与VVL结合力[（0.36±0.12）U]高于孤立性血尿组[（0.32±0.08）U]（P＜0.05）.IgA肾病不同病理分级组血清IgA1与VVL结合力比较有差异,其中Ⅰ级＋Ⅱ级组最高[（0.39±0.12）U]（P＜0.05）.以正常对照组血清IgA1与VVL结合力的±2s为诊断IgA肾病的临界值,诊断灵敏度为24.1%,特异度为100%,阳性预告值为100%,阴性预告值为45%;以±s为诊断IgA肾病的临界值,灵敏度为44.8%,特异度72.2%,阳性预告值为72.2%,阴性预告值为44.8%.结论：IgA肾病患者血清IgA1半乳糖水平低.检测血清IgA1半乳糖水平对于诊断IgA肾病具有一定临床价值,仍需扩大样本量进一步证实.

Objective ：To detect the serum level of IgA1 galactose in patients with IgA nephropathy （IgAN） and to explore its use in diagnosis of IgAN. Methods： From May 2007 to February 2008,29 biopsy-proven IgAN patients registered to the First Affiliated Hospital of Sun Yat-sen University were included in the IgAN group. These IgAN patients were further divided into the isolated hematuria sub-group （n = 14） and non-isolated hematuria group （n = 15） based on clinical manifestations,and also divided into three sub-groups according to pathological grading： grades Ⅰ/Ⅱ group （n =9）,grade Ⅲ group （n =9） and grade Ⅳ/Ⅴ group （n = 11）. A contemporary cohort of 18 healthy individuals was included in the normal controls group, and another of 18 patients with other renal diseases except IgAN or Henoch-Sehonlein purpura nephritis was included in disease control group. The age and gender distribution were comparable among the groups with no statistical differences （ P 〉 0.05 ）. The binding capacity of IgAl to vicia villasa lectin （VVL） as a surrogate for IgAl-galactose level was detected by enzyme linked immunosorbent assay （ELISA）. The sensitivity, specificity, positive and negative predictive values for diagnosis of IgAN with IgAl galactose level was analyzed. Results：The binding capacity of IgA11 to VVL was significantly higher in IgAN patients [ （0.34 ± 0. 1 ） U ] than in healthy controls [ （ 0.27 ± 0.06 ） U ] or patients with other renal diseases [ （0.28 ± 0.07 ） U ] （ P 〈 0. 05 ）, and in non-isolated hematuria sub-group of IgAN patients [ （0.36 ±- 0. 12） U] than in isolated hematuria sub-group of IgAN patients [ （0.32 ±0.08） U] （P 〈0.05）. The VVL binding capacity of IgA1 also differed among pathology-based subgroups, with the highest level found in IgAN patients with grades Ⅰ/Ⅱ [ （0.39 ± 0. 12） U ] （ P 〈 0.05 ）. Given （x^-± 2 s） of the VVL-binding capacity of serum IgA1 in normal controls as a critical value, the diagnosis showed a sensitivity of 24. 1%, specificity of 100%, positive predictive value of 100% and negative predictive value of 45%. These figures were 44.8% ,72.2% ,72.2% and 44.8% when （x^-± s） of the VVL-binding capacity of serum IgA1 in normal controls was used as a critical value. Conclusion： Low level of serum IgA1 galactose was found in IgAN patients. Detection of serum IgA1 galactose level by EEISA may have a role in diagnosis of IgAN but need to be further confirmed in a cohort with larger sample size.