Department of Pathology and Cell Biology, Division of Renal Pathology, and
Department of Medicine, Division of Nephrology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, New York.
Clin J Am Soc Nephrol. 2014 Jun 6;9(6):1033-9. doi: 10.2215/CJN.11951113. Epub 2014 Apr 10.
Patients with IgA nephropathy typically present with hematuria and subnephrotic proteinuria. Nephrotic syndrome is uncommon in IgA nephropathy, and when present, it is usually associated with severe histologic features, such as endocapillary proliferation, segmental sclerosis, and crescent formation. Rarely, patients with IgA nephropathy present with nephrotic syndrome and only mild mesangial disease. This study sought to better characterize these patients.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A retrospective review of cases of IgA nephropathy diagnosed from 2004 to 2011 identified patients with nephrotic range proteinuria and histologically mild IgA nephropathy. Specifically, using the Oxford Classification of IgA Nephropathy, we identified cases that lacked endocapillary proliferation or segmental sclerosis.
The cohort consisted of 17 patients, including 10 men and 15 adults. The median serum creatinine was 0.9 mg/dl (range=0.7-3.1), median 24-hour urine protein was 8.0 g/d (3.0-18.0 g), and 14 patients were fully nephrotic, whereas the remaining 3 patients fulfilled two of three criteria for nephrotic syndrome. Biopsies revealed IgA-dominant or codominant deposits accompanied by mesangial proliferation in 14 patients (82.4%). Electron microscopy showed mesangial deposits and extensive foot process effacement (median=90%). Initial treatment consisted of corticosteroids, although many patients required additional agents to maintain remission status. Over a median follow-up of 20 months (2.2-82 months), 14 patients experienced a complete response, and 3 patients showed a partial response, with a median response time of 2 months (0.5-27 months). At least one relapse of nephrotic syndrome occurred in nine patients (53%). All patients exhibited stable or improved renal function over the follow-up period.
The findings in this cohort and previous studies suggest that rare cases of mild IgA nephropathy with nephrotic range proteinuria exhibit a clinical presentation, biopsy findings, treatment response, and outcome more typical of IgA nephropathy with superimposed minimal change disease. This study favors the view that such cases represent a dual glomerulopathy.
IgA 肾病患者通常表现为血尿和亚肾病范围蛋白尿。肾病综合征在 IgA 肾病中并不常见，当出现时，通常与严重的组织学特征有关，如毛细血管内增殖、节段性硬化和新月体形成。罕见情况下，IgA 肾病患者表现为肾病综合征且仅存在轻度系膜疾病。本研究旨在更好地描述这些患者。
设计、设置、参与者和测量：对 2004 年至 2011 年诊断为 IgA 肾病的病例进行回顾性分析，确定具有肾病范围蛋白尿且组织学表现为轻度 IgA 肾病的患者。具体而言，我们根据 IgA 肾病的牛津分类，确定了缺乏毛细血管内增殖或节段性硬化的病例。
该队列包括 17 例患者，其中男性 10 例，成人 15 例。中位血清肌酐为 0.9mg/dl（范围=0.7-3.1），中位 24 小时尿蛋白为 8.0g/d（3.0-18.0g），14 例患者完全符合肾病综合征标准，而其余 3 例患者符合肾病综合征标准中的两项。活检显示 14 例患者（82.4%）存在 IgA 主导或共主导沉积，伴有系膜增殖。电子显微镜显示系膜沉积和广泛的足突融合（中位数=90%）。初始治疗包括皮质类固醇，尽管许多患者需要额外的药物来维持缓解状态。中位随访 20 个月（2.2-82 个月）后，14 例患者完全缓解，3 例患者部分缓解，中位缓解时间为 2 个月（0.5-27 个月）。9 例患者（53%）至少发生一次肾病综合征复发。所有患者在随访期间肾功能稳定或改善。
本队列和以往研究的结果表明，罕见的具有肾病范围蛋白尿的轻度 IgA 肾病病例表现出的临床表现、活检结果、治疗反应和结局更符合伴有微小病变叠加的 IgA 肾病。本研究倾向于认为这些病例代表双重肾小球疾病。
