目的 探讨狼疮肾炎（LN）患者血清肾胺酶（renalase）水平与疾病活动度的相关关系。 方法 入选2012年3月至2013年3月上海交通大学医学院附属仁济医院经肾活检确诊的LN患者70例，根据系统性红斑狼疮基本活动指数（SLEDAI）将患者分为活动组（SLEDAI≥8）和非活动组（SLEDAI﹤8）；同时纳入性别、年龄匹配的健康对照35例。留取20例活动性LN患者激素联合免疫抑制剂治疗前及治疗6个月后血标本。采用ELISA法检测血清肾胺酶水平。比较LN患者血清肾胺酶水平与健康人群的差异，用受试者工作特征曲线（ROC）及曲线下面积（AUC）评价肾胺酶预测LN活动性的敏感度和特异度；Logistic多因素回归法分析影响LN患者疾病活动的相关因素。 结果 LN患者血清肾胺酶水平明显高于健康对照人群（P﹤0.01）； LN活动组血清肾胺酶水平明显高于非活动组（P﹤0.01）。相关性分析结果提示，LN患者血清肾胺酶水平与SLEDAI评分、24 h尿蛋白量、血沉及抗dsDNA抗体呈正相关；与血浆白蛋白、补体C3水平呈负相关。肾胺酶预测LN活动性的AUC为0.894，敏感度为82.86%，特异度为89.86%。与治疗前相比，活动性LN治疗后患者血清肾胺酶水平明显下降（P﹤0.05）。Logistic回归分析结果显示，血清肾胺酶（OR=1.078，95%CI：1.031～1.120，P=0.001）和补体C3（OR=0.022，95%CI：0.002～0.326，P=0.005）是LN患者疾病活动的独立预测指标。 结论 LN患者血清肾胺酶水平较健康人群明显升高，血清肾胺酶水平与LN疾病活动度相关。血清肾胺酶可成为判断LN患者疾病活动的指标之一。

Objective To investigate the relationship between serum renalase and disease activity in lupus nephritis (LN). Methods Total of 70 patients with LN and 35 healthy volunteers admitted in Renji Hospital of Shanghai Jiao Tong University from March 2012 to March 2013 were enrolled in the study. LN patients were classified into two groups according to their systemic lupus erythematosus disease activity index (SLEDAI) scores: patients with SELDAI score lower than 8 were defined as inactive LN while others were defined as active LN. Serum samples were collected after an overnight fast and serum renalase level was determined by ELISA. Twenty active LN patients were followed up for six-months, and serum renalase was also determined before and after treatment. The differences in serum renalase level between LN patients and healthy controls were assessed, as well as the association of serum renalase with disease activity in LN. Results In 70 LN patients, 35 were classified active LN while others were inactive LN. Serum renalase level was significantly higher in LN patients than than in healthy controls (P﹤0.01). Moreover, active LN patients had higher serum renalase level compared to patients with inactive LN (P﹤0.01). Active LN patients had higher 24-hour urine protein excretion, erythrocyte sedimentation rate and anti-dsDNA antibody titers than inactive LN patients. Serum albumin was lower in inactive LN patients compared to active LN patients. There were no differences in gender, age, blood pressure and C-reactive protein between the two groups. Serum renalase levels were positively correlated with SLEDAI, 24-hour urine protein excretion, ds-DNA and ESR but inversely correlated with serum albumin and C3. Renalase amounts decreased significantly after six-months of standard therapy. The performance of renalase as a marker for diagnosis of active LN was 0.894 with a cutoff value of 66.67 mg/L. Logistic regression showed that serum renalase (OR=1.078, 95%CI 1.031-1.120, P=0.001) and complement C3 (OR=0.022, 95%CI 0.002-0.326, P=0.005) is independent indicators for disease activity in LN. Conclusions Serum renalase level was correlated with disease activity in LN. Serum renalase may serve as a potential indicator for disease activity in LN.