Monoclonal gammopathies are characterized by the overproduction of monoclonal Ig (MIg) detectable in the serum or urine resulting from a clonal proliferation of plasma cells or B lymphocytes. The underlying hematologic conditions range from malignant neoplasms of plasma cells or B lymphocytes, including multiple myeloma and B-cell lymphoproliferative disorders, to nonmalignant small clonal proliferations. The term MGUS implies presence of an MIg in the setting of a “benign” hematologic condition without renal or other end organ damage. The term MGRS was recently introduced to indicate monoclonal gammopathy with MIg-associated renal disease in the absence of hematologic malignancy. Most MIg-associated renal diseases result from the direct deposition of nephrotoxic MIg or its light- or heavy-chain fragments in various renal tissue compartments. Immunofluorescence microscopy is essential to identify the offending MIg and define its tissue distribution. Mass spectrometry is helpful in difficult cases. Conditions caused by direct tissue deposition of MIg include common disorders, such as cast nephropathy, amyloidosis, and MIg deposition diseases, as well as uncommon disorders, such as immunotactoid glomerulopathy, proliferative GN with MIg deposits, light-chain proximal tubulopathy, and the rare entities of crystal-storing histiocytosis and crystalglobulinemia. Indirect mechanisms of MIg-induced renal disease can cause C3 glomerulopathy or thrombotic microangiopathy without tissue MIg deposits. Treatment of MIg-associated renal disease is aimed at eliminating the clonal plasma cell or B-cell population as appropriate. Both the renal and the underlying hematologic disorders influence the management and prognosis of MIg-associated renal diseases.

单克隆变态反应的特征在于，浆细胞或B淋巴细胞的克隆增殖导致在血清或尿液中检测到的单克隆Ig（MIg）过量产生。潜在的血液学疾病范围从浆细胞或B淋巴细胞的恶性肿瘤（包括多发性骨髓瘤和B细胞淋巴增生性疾病）到非恶性小克隆增生。术语MGUS表示在“良性”血液学状况下存在MIg，而没有肾脏或其他终末器官损害。最近引入了术语MGRS，以指示在没有血液系统恶性肿瘤的情况下，伴有MIg相关性肾脏疾病的单克隆丙种球蛋白病。大多数与MIg相关的肾脏疾病是由肾毒性MIg或其轻链或重链片段直接沉积在各种肾脏组织区室中引起的。免疫荧光显微镜检查对于识别有问题的MIg并定义其组织分布至关重要。质谱在困难情况下很有帮助。由MIg的直接组织沉积引起的疾病包括常见的疾病，例如铸型肾病，淀粉样变性病和MIg沉积疾病，以及罕见的疾病，例如免疫性类触性肾小球病，具有MIg沉积的增殖性GN，轻链近端肾小管病变和罕见的疾病晶体存储组织细胞增生和晶体球蛋白血症的实体。MIg诱发的肾脏疾病的间接机制可导致C3肾小球病或血栓性微血管病，而无组织MIg沉积。与MIg相关的肾脏疾病的治疗旨在消除适当的克隆浆细胞或B细胞。