儿童C1q肾病临床病理研究

目的 :探讨儿童C1q肾病临床病理特征及诊断与治疗。方法 :分析 8例C1q肾病患儿临床病理特点及激素或免疫抑制剂治疗效应 ,并与同期 77例原发性NS患儿作比较。结果 :8例C1q肾病患儿临床上大多表现为原发性NS(6例 ) ,仅 2例表现为肾炎综合征和单纯性血尿。LM主要包括MC(3例 )、MsPGN(2例 )、FSGS(2例 )和ECPGN(1例 )。IF显示明显的系膜区C1q沉积 ,伴或不伴有Ig和补体沉积。EM检查仅 1例有系膜区和内皮下电子致密物沉积。与原发性NS相比 ,6例表现为NS的C1q肾病患儿对泼尼松初次治疗产生耐药的相对危险度为 2 1(P <0 .0 0 1) ,但对免疫抑制剂治疗均敏感。结论 :儿童C1q肾病临床上以对激素耐药的NS为常见表现 ,IF是其主要诊断依据 ,使用免疫抑制剂治疗有效     

C1q肾病的诊断及治疗

C1q肾病是一种以系膜增生为主的肾小球疾病,其特点为免疫荧光染色可见系膜区高强度C1q沉积,电镜下可见系膜区电子致密物沉积,根据组织病理学特点主要分为3类,包括微小病变(MCD)、局灶节段性肾小球硬化(FSGS)和免疫介导的增生性肾小球肾炎。C1q肾病的临床表现具有多样性,可表现为肾炎或肾病范围内蛋白尿,伴有或不伴有血尿和肾功能损伤。虽然目前糖皮质激素是治疗C1q肾病的主要方法,但多数研究认为C1q肾病对糖皮质激素治疗反应较差。中西医结合治疗有望提高C1q肾病的疗效。     

环孢菌素在肾病中的应用——微小病变和局灶节段小球硬化

环孢菌素是一种新型的免疫抑制剂,近年试用于肾病,对激素耐药的部分病人中取得了较好的疗效。病例和方法 (1)肾病综合征(不仅为蛋白尿),(2)激素耐药和激素依赖,(3)微小病变(MCD),(4)局灶节段小球硬化(FSGS),任何系统性疾病所致肾病(NS)均排除,初剂量5mg/kg/dag,分二次给药,全血谷值为200～860ng/ml(血清谷值为50—200ng/ml)。结果初步研究中113例病例结果分析,成人MCD18例有效,3例无效,儿童MCD37例有效,13例无效,成人FSGS 6例均有效,儿童FSGS18例有效,12例无效。先前对激素敏感但多次反复的     

呈局灶节段性肾小球硬化的IgA肾病临床病理特点

目的探讨呈局灶节段性肾小球硬化（FSGS）的IgA肾病（IgAN）的临床和病理特点。方法选取我院1988年1月至2002年2月经肾活检确诊为IgAN的患者587例，其中呈FSGS85例，呈弥漫性系膜增生性肾小球肾炎（MsPGN）162例，呈弥漫性系膜增生性肾小球肾炎伴局灶节段性肾小球硬化（MsPGN伴FSGS）185例，比较3种类型IgAN临床和病理资料。结果FSGS型IgAN占同期所有IgAN的14．5％，临床类型以大量蛋白尿型为主，占37．64％。肾小球球囊黏连发生率高达74．12％，小管间质纤维化发生率97．65％，病理分级以LeeⅣ～Ⅴ级为主，免疫病理以IgA—MG型为主，与MsPGN伴FSGS型和MsPGN型的IgAN相比，FSGS型IgAN病程较长，高血压、肾功能不全发生率较高（P〈0．05），而血尿的发生率与后两者无明显区别。结论呈FSGS型IgAN大量蛋白尿、高血压、肾功能不全的发生率高，病变较重，预后较差。     

环孢素A在不同病理类型原发性肾病综合征治疗中的应用

肾病综合征可分为原发性和继发性,原发性肾病综合征中常见的病理类犁包括以下5种:微小病变(MCD)、膜性肾病(MN)、局灶节段硬化性肾小球肾炎(FSGS)、系膜增殖性肾小球肾炎(MsPGN)和膜增殖性肾小球肾炎(MPGN),较为常见的为前4种.MCD在小儿及老年人较为常见,MN多发于老年人,而MsPGN为我同较为常见的肾病综合征,FSGS对治疗反应不佳,通常预后较差,MPGN则较为少见.     

儿童隐匿性肾炎的临床和病理研究

目的：探讨儿童隐匿性肾炎的临床和肾组织病理改变特点及其关系。方法：回顾性分析肾活检的323例隐匿性肾炎患儿的临床和肾组织病理改变情况。结果：323例隐匿性肾炎患儿中，单纯性血尿229例，单纯性蛋白尿19例，血尿伴蛋白尿75例。肾组织病理改变类型包括：轻微病变103例（31，89％）、基本正常74例（22．91％）、IgA肾病（IgAN）73例（22．60％）、薄基底膜病（TBMN）27例（8．36％）、系膜增生性肾炎（MsPGN）18例（5．57％）、局灶增生性肾炎（FPGN）10例（3．10％）、膜性肾病（MN）8例（2，48％）、局灶节段肾小球硬化（舢）8例（2．48％）、微小病变（MCD）1例（0，31％）、IgM肾病（IgMN）1例（0．31％）。单纯性血尿组中肾组织结构基本正常的比例较血尿伴蛋白尿组明显偏高（P〈0，01）；血尿伴蛋白尿组中IgAN的比例高于单纯性血尿组和单纯性蛋白尿组（分别P〈0．01、P〈0．05）。IgAN的Lee分级：单纯性血尿组中Ⅰ、Ⅱ级85．00％，Ⅲ级及以上15．00％；血尿伴蛋白尿组中Ⅰ、Ⅱ级58．10％，Ⅲ级及以上41．90％，明显高于单纯性血尿组（x^2=6．47，P〈0．05）。结论：儿童隐匿性肾炎的病理以轻微病变、基本正常、IgAN为常见表现，血尿伴蛋白尿患儿病变较单纯性血尿患儿为重。     

儿童毛细血管内皮细胞增生性紫癜性肾炎的临床病理及预后分析

目的 探讨以弥漫性毛细血管内皮细胞增生为主要病理表现的紫癜性肾炎（DEP-HSPN）的临床、病理及预后。 方法 回顾性分析本院近10年来经肾活检确诊的8例DEP-HSPN患儿临床、病理和预后资料,并分别与同病理级别或具有同等蛋白尿水平（肾病水平蛋白尿）的非DEP-HSPN患儿进行比较。 结果 （1）DEP-HSPN起病急,临床表现重,8例患儿中,4例临床表现为肾炎性肾病,3例表现为肾病水平蛋白尿伴血尿,1例呈急性肾炎综合征,4例患儿合并有肉眼血尿。病理分级均为Ⅲ-b级,光镜主要表现为弥漫性毛细血管内皮细胞和系膜细胞增生,常合并毛细血管袢坏死及肾小球内炎性细胞浸润,4例患儿合并细胞性新月体。（2）与病理为Ⅲ-b级的非DEP-HSPN患儿比较,DEP-HSPN患儿病程较短,临床多见肉眼血尿,24 h尿蛋白量高,更多呈肾炎性肾病表现。病理上,DEP-HSPN肾小球毛细血管袢坏死更常见。与具有肾病水平蛋白尿的非DEP-HSPN患儿相比,DEP-HSPN合并新月体的比例较低。（3）8例患儿均采用口服泼尼松联合静脉滴注环磷酰胺（CTX）冲击,病程早期给予2个疗程甲泼尼龙冲击治疗方案。平均随防（7.00±2.20）月,1例临床痊愈,5例持续镜下血尿,2例微量蛋白尿及持续镜下血尿。两组患儿预后差异无统计学意义。 结论 DEP-HSPN起病较急,临床以大量蛋白尿或肾炎性肾病为主要表现,并且常合并肉眼血尿。病程早期给予积极的免疫抑制剂治疗常能取得较满意的近期疗效。     

儿童原发性肾病综合征中血管生成素样蛋白3的表达

目的 研究血管生成素样蛋白3 (angiopoietin-like 3 protein，ANGPTL3)在儿童原发性肾病综合征(PNS)患者肾组织中表达分布及其参与蛋白尿发生的机制。方法 ANGPTL3分别与足细胞核标记抗原(WT1)、基底膜标记抗原类肝素硫酸蛋白多糖perlecan进行双标记法免疫荧光染色。应用免疫组化的方法检测ANGPTL3和perlecan在不同病理类型的69例PNS及血尿患儿，包括微小病变(MCD)31例、膜性肾病(MN)6例、局灶节段硬化性肾小球肾炎(FSGS)6例、IgA肾病16例、薄基底膜肾病(TBMN)10例以及2例正常对照肾组织中表达，并以IMS彩色图像分析系统量化为免疫组化指数。在MCD病例中将尿蛋白肌酐比值分别与肾组织中ANGPTL3和perlecan肾小球内染色强度及电镜下平均足突宽度(FWP)进行相关分析。对不同病理诊断时间(发病至肾穿刺)分组患儿肾小球ANGPTL3和perlecan的表达进行比较。结果 (1)ANGPTL3在正常肾组织呈现微弱的沉积，而在不同病理类型的肾病综合征患儿的肾组织的肾小球和肾小管存在不同程度的表达。肾小球内ANGPTL3表达量在MCD(7.49±1.96)、MN(6.27±0.98)中显著高于正常对照(0.02±0.001)、TBMN(0.02±0.001)及FSGS(3.14±0.49)(均P < 0.05)。在IgA肾病(系膜增生型)中，蛋白尿组肾小球中ANGPTL3表达量显著高于单纯血尿组(1.90±0.81比0.03±0.01， P < 0.05)。(2) 在MCD肾组织中，WT1及perlecan荧光双标记染色显示， ANGPTL3在足细胞胞浆及沿肾小球血管袢表达。(3) ANGPTL3在肾小球表达量分别与尿蛋白肌酐比值及电镜下平均足突宽度正相关(r为0.86、0.84，P均<0.05)，并与perlecan在肾小球内表达量负相关(r为-0.83，P < 0.05)。(4)不同发病年限的MCD患儿肾组织中肾小球ANGPTL3及perlecan的表达无显著性差异。结论 在不同程度的蛋白尿及不同足突融合程度的肾组织中存在ANGPTL3的表达差异。在MCD中，ANGPTL3主要在足细胞胞浆表达，肾小球中ANGPTL3的表达与蛋白尿程度及足细胞融合程度呈正相关。     

他克莫司在肾脏病中的合理应用

他克莫司是一种新型免疫抑制剂,可保护足细胞,降低尿蛋白。近年来研究表明他克莫司对多种慢性肾脏病的治疗有效,他克莫司治疗原发性膜性肾病(IMN)缓解率较环磷酰胺(CTX)方案提高;可有效安全治疗微小病变型肾病(MCD);在难治性局灶性节段性肾小球硬化(FSGS)及难治性狼疮肾炎(LN)治疗中可降低蛋白尿,临床缓解率高,耐受性好;治疗激素抵抗型儿童肾病综合征疗效更好且安全。改善全球肾脏病预后(KDIGO)指南推荐他克莫司应用于IMN、MCD、FSGS、LN和儿童肾病综合征治疗。同时,他克莫司也可发生感染、震颤、失眠、血肌酐升高、高血糖、高血压和感觉异常等不良反应。因此,在肾脏病的治疗中应注意合理、有效和安全的使用。     

霉酚酸酯对难治性肾病综合征和弥漫增殖性狼疮肾炎的疗效比较

目的 :观察霉酚酸酯 (MMF)在治疗原发性难治性肾病综合征与弥漫增殖性狼疮性肾炎的疗效比较。方法 :观察难治性肾病综合征 15例及同期弥漫增殖性狼疮性肾炎 (ⅣLN) 18例。以强的松 0 .4mg～ 0 .7mg·kg-1·d-1联合MMF1.0～ 1.5 2次 /d ,3～ 6个月后减半维持 1年 ,定期随访。结果 :以强的松联合MMF治疗 ,对ⅣLN疗效良好 ,完全缓解率达 10 0 % ,其中 3个月内缓解 12例 ,6个月内缓解 17例。而在原发性肾病综合征中 ,对MCD和MsPGN疗效良好 ,与ⅣLN相似 ,在MN中 2例完全缓解 ,3例仅部分缓解 ,2例无效。而后者均在 6～ 9个月间 ,对FSGS和MPGN仅 1例在 9个月后部分缓解 ,2例无效。结论 :MMF对MCD和MsPGN效果良好 ,对MN显示部分疗效 ,对FSGS和MPGN的疗效较差。总体上MMF对难治性肾病综合征的疗效逊于ⅣLN。     

肾病综合征患者肾组织podocin的表达

目的 观察不同病理类型&#65380; 不同激素反应性肾病综合征(NS)患者肾小球足细胞中podocin的表达和分布特征&#65377;方法 肾组织作冰冻切片免疫荧光双染色, 以激光共聚焦显微镜采集图像&#65377;与定位标志Ⅳ型胶原α3链比较&#65377; 受检NS患者21例, 其中局灶节段性肾小球硬化(FSGS)12例(难治性7例, 非难治性5例)&#65380; 微小病变(MCD)5例&#65380; 膜性肾病(MN)4例;正常肾组织对照3例&#65377;采用LSM 510图像处理系统进行处理&#65377;荧光强度以吸光度表示&#65377; 结果 (1)podocin在正常肾组织沿肾小球基底膜呈连续&#65380; 线形分布&#65377;部分FSGS患者podocin的分布呈点状&#65380; 短线条状, 少数患者未见podocin沉积&#65377;(2)FSGS患者肾小球中podocin表达量(80.5±33.5)与对照正常肾组织(138.4±38.1)比较,显著减少(P=0.0211), 其中难治性FSGS(67.2±30.5)与正常肾组织的差异有统计学意义(P=0.0131); 非难治性FSGS患者(99.0±31.0)与正常肾组织的差异无统计学意义(P=0.1585)&#65377;(3)MCD(112.1±47.6)&#65380; MN(92.5±34.8)患者podocin的表达量亦降低,与正常肾组织比较,无统计学意义(P=0.4497, P=0.1570)&#65377;(4)不同病理类型各组NS患者肾小球中podocin表达量的差异均无统计学意义(P > 0.05)&#65377;结论 FSGS的NS患者肾小球中podocin的表达减少, 难治性FSGS患者尤为明显, 部分FSGS患者podocin分布发生改变&#65377;podocin的检测可能在FSGS激素疗效评价方面有一定价值&#65377;     

C1Q nephropathy in children

C1q nephropathy (C1qNP) is a peculiar form of glomerulonephritis characterized by mesangial immunoglobulin and complement deposits, predominantly C1q, with no evidence of systemic lupus erythematosus. We describe the incidence, manifestation, histopathologic findings, follow-up, treatment and outcome of C1qNP. Twelve C1qNP patients were identified among 131 children who had undergone renal biopsy, accounting for a 9.16% incidence of C1qNP. Light microscopy examination showed focal segmental glomerulosclerosis (FSGS) with or without diffuse mesangial proliferation (n=6), minimal change disease (MCD) (n=4) or focal glomerulonephritis (n=2). C1q deposits were found in all, while electron microscopy revealed visible deposits in nine cases. Eight children presented with nephrotic syndrome, while one had nephrotic proteinuria and renal insufficiency that progressed to end-stage renal failure. The remaining three patients presented with nonnephrotic proteinuria associated with microhematuria, hypertension or renal insufficiency. Only one nephrotic syndrome patient responded excellently to corticosteroids, while four became corticosteroid dependent, and three were corticosteroid resistant, showing a very poor response to other immunosuppressive therapy as well. Patients with non-nephrotic proteinuria demonstrated fixed laboratory findings. Most C1qNP patients had FSGS or MCD, the majority of them presenting with corticosteroid-dependent or corticosteroid-resistant nephrotic syndrome. The latter showed a very poor response to any immunosuppressive therapy and high risk for progressive renal insufficiency.     

Cyclosporin in idiopathic glomerular disease associated with the nephrotic syndrome : workshop recommendations

Management of idiopathic glomerular disease associated with nephrotic syndrome (INS) remains controversial and one of the most complex areas relates to utilization of the drug cyclosporin. This is despite its demonstrated effectiveness in several histologic types of the INS in randomized controlled trials. Cyclosporin is effective in inducing remission of proteinuria in approximately 80% of steroid-sensitive cases of minimal change disease (MCD). Cyclosporin is also effective in both the induction of remission and long-term preservation of renal function in steroid-dependent/-resistant MCD and steroid-resistant focal segmental glomerulosclerosis (FSGS). The overall response rate in FSGS is lower than in MCD, and long-term therapy (>12 months) may be required to both achieve remission and sustain it. Cyclosporin therapy is also of benefit in reducing proteinuria in 70-80% of patients with steroid-resistant membranous nephropathy (MGN). In MGN, the maximum benefit is often delayed compared to MCD (>12 weeks). Cyclosporin is generally well tolerated and safe. The major concern remains the nephrotoxicity, but with careful monitoring of the patient's renal function; minimizing the maintenance dose and utilizing repeat renal biopsy in those receiving long-term therapy, this risk can be minimized. The algorithms have been developed derived from the best evidence in the literature in each of the histologic types to help provide a guide to the integration of cyclosporin into the management of INS for the practicing nephrologist.     

Is single-daily low-dose cyclosporine therapy really effective in children with idiopathic frequent-relapsing nephrotic syndrome?

BACKGROUND: A recent study on renal transplant patients has shown that a single dose of cyclosporine (CsA) has added the advantage of decreasing dosages and adverse effects, while maintaining graft function. However, the efficacy of this regimen in children with idiopathic frequent-relapsing nephrotic syndrome (NS) remains controversial. METHODS: 20 children with steroid-dependent NS or CsA-dependent NS (18 with minimal change disease, MCD and 2 with focal segmental glomerulosclerosis, FSGS) were enrolled in this prospective study. CsA was commenced at 1.5 a 2 mg/kg, given as a single daily dose before breakfast, and the dose was adjusted to reach 2 hours post-dose CsA levels (C2) of 600 - 800 ng/ml. RESULTS: In 9 out of 18 patients with MCD, treatment with single-daily CsA for a median of 13 months (range 7 - 21) resulted in a reduction of mean minimum prednisolone (PSL) dose from 1.1 A+/- 0.55 to 0.04 A+/- 0.09 mg/kg on alternate days (p < 0.01), and the median relapse rate from 1.3 (1.1 - 2.5) to 0 (0 - 0.2) episodes/6 months (p < 0.01). Of them, PSL could be weaned off in 7 patients (4 of 6 with steroid-dependent NS, only 3 of 14 with CsA-dependent NS) without relapse of NS while on this therapy. However, 11 out of 20 were considered to have treatment failure: 1 with steroid-dependent NS and 10 with CsA-dependent NS. In 2 patients having FSGS, this method showed no beneficial effects. In 18 patients with MCD, relapse free ratio on single-daily CsA therapy was significantly higher in patients whose average C2 levels were greater than 700 ng/ml (p < 0.05). CONCLUSIONS: Our experience demonstrates that single-daily low-dose CsA therapy maintaining C2 levels greater than 700 ng/ml may be effective in children with steroid-dependent NS or MCD, with no relapse. In contrast, the usefulness of this regimen in children with CsA-dependent NS appears to be limited.     

Glucocorticoid receptors expression and histopathological types in children with nephrotic syndrome

Background: Some children with idiopathic nephrotic syndrome (NS) patients fail to respond even when given high dose of steroid. The aim of this study was to assess the GCR expression on the T lymphocytes of children with NS and its relation to the response to steroid and to histopathological type. Methods: Forty-six pediatric patients with idiopathic NS and 20 age and sex matched apparently healthy children as controls were included. Flow cytometry was employed to determine the percentage of CD3+/GCR+ cells which then correlated with pattern of steroid response. Renal biopsy was done for steroid-dependent and steroid-resistant cases for determination of the underlying histopathological type. Results: The mean percentage of T lymphocyte expression of GCRs (CD3+/GCR) was significantly higher in early steroid responders than in late responders and was slightly lower than the controls. There was a significantly lower GCRs expression in steroid-resistant patients in comparison to early responders, late responders and controls. Renal biopsy showed that most cases of late responders were of the focal segmental glomerulosclerosis (FSGS) type. The mean percentage of lymphocyte expression of GCRs was significantly higher in patients with minimal change disease (MCD) compared to patients with FSGS. Conclusion: Evaluation of the expression of intracellular GCRs in T lymphocytes at time of diagnosis of NS can predict the response to steroid therapy and can help in determination of the outcome of NS patients regarding future relapses.     

Long-term outcome of children with steroid-resistant nephrotic syndrome treated with tacrolimus

We report the outcome of our single-center, long-term follow-up study of tacrolimus therapy in children with steroid-resistant nephrotic syndrome (SRNS). All cases of nephrotic syndrome (NS) with kidney biopsies treated at our center between January 2000 and July 2008 were reviewed. Children with systemic lupus erythematosus and steroid-dependent NS were excluded. Nineteen children with SRNS received tacrolimus. Histopathological analysis of the biopsy revealed the underlying conditions of these 19 patients to be focal segmental glomerulosclerosis (ten patients), C1q nephropathy (four), membranous nephropathy (two), minimal change disease (one), membranoproliferative glomerulonephritis (one), and immunoglobulin A nephropathy (one). The mean follow-up was 55 months, and the median age of the patient cohort was 10 years. We observed complete remission in 11 (58%) patients, partial remission in six (32%), and failure to respond in two (9%). The median time to response was 8 weeks. Side effects were mild and transient (one case of acute kidney injury and three cases of hyperglycemia). The initial rate for combined partial and complete remission of the NS in children with SRNS was 81%, which was sustained in 58% of the patients on follow-up. Among children with FSGS, the sustained remission rate was 50%, while 40% progressed to end-stage renal disease (ESRD) (mean time 52 months). Based on the results of this study, we conclude that tacrolimus is an effective and well-tolerated therapeutic option for the treatment of SRNS in children. However, the occurrence of relapses of the NS with progression to ESRD during the long-term follow-up indicates the need for careful monitoring of such patients.     

C1q nephropathy: a variant of focal segmental glomerulosclerosis

BACKGROUND: C1q nephropathy is a poorly understood and controversial entity with distinctive immunopathologic features. In order to better define the clinical-pathologic spectrum, we report the largest single-center series. METHODS: Nineteen biopsies with C1q nephropathy were identified from among 8909 native kidney biopsies received from 1994 to 2002 (0.21%). Defining criteria included (1). dominant or co-dominant immunofluorescence staining for C1q, (2). mesangial electron dense deposits, and (3). no clinical or serologic evidence of systemic lupus erythematosus (SLE). RESULTS: The 19 patients were predominantly African American (73.7%), female (73.7%), young adults and children (range, 3 to 42 years; mean, 24.2 years). Presentation included nephrotic range proteinuria (78.9%), nephrotic syndrome (50%), renal insufficiency (27.8%), and hematuria (22.2%). No patient had hypocomplementemia or evidence of underlying autoimmune or infectious disease. Renal biopsy revealed focal segmental glomerulosclerosis (FSGS) in 17 (including six collapsing and two cellular) and minimal-change disease (MCD) in two. All biopsies displayed co-deposits of immunoglobulin G (IgG), with more variable IgM (84.2%), IgA (31.6%), and C3 (52.6%). Foot process effacement varied from 20% to 100% (mean, 51%). Twelve of 16 patients with available follow-up received immunosuppressive therapy. One patient had complete remission of proteinuria and six had partial remission. Four patients with FSGS pattern had progressive renal insufficiency, including two who reached end-stage renal disease (ESRD). Median time from biopsy to ESRD was 81 months. On multivariate analysis, the best correlate of renal insufficiency at biopsy and at follow-up was the degree of tubular atrophy and interstitial fibrosis (P = 0.0495 and 0.0341, respectively). CONCLUSION: C1q nephropathy falls within the clinical-pathologic spectrum of MCD/FSGS. Although further studies are needed to determine the pathomechanism of C1q deposition, we hypothesize that it may be a non-specific marker of increased mesangial trafficking in the setting of glomerular proteinuria.     

Urinary N-acetyl-beta-glucosaminidase excretion is a marker of tubular cell dysfunction and a predictor of outcome in primary glomerulonephritis.

BACKGROUND: The urinary excretion of N-acetyl-beta-glucosamynidase (NAG) is increased in subjects exposed to substances toxic for renal tubular cells. In experimental and human glomerular diseases, its increased excretion is probably due to the dysfunction of tubular epithelial cells induced by increased traffic of proteins in the tubular lumen. The first aim of this study was to evaluate whether NAG excretion is correlated not only with the amount of proteinuria but also with some proteinuric components which reflect both glomerular capillary wall damage (IgG) and an impairment of tubular reabsorption of microproteins (alpha(1) microglobulin). The second aim was to assess whether NAG excretion has a predictive value on functional outcome and response to therapy. METHODS: In 136 patients with primary glomerulonephritis [74 with idiopathic membranous nephropathy (IMN), 44 with primary focal segmental glomerulosclerosis (FSGS) and 18 with minimal change disease (MCD)] urinary NAG excretion was measured by a colorimetric method and expressed in units per gram of urinary creatinine. RESULTS: Using univariate linear regression analysis NAG excretion in all 136 patients was significantly dependent on IgG excretion, 24-h proteinuria, fractional excretion of alpha(1) microglobulin (FE alpha(1)m) and diagnosis. Using multiple linear regression analysis, NAG excretion was significantly dependent only on IgG excretion and 24-h proteinuria. Limiting the analysis to 67 patients with nephrotic syndrome (NS) and baseline normal renal function, by multiple linear regression, NAG excretion was significantly dependent on IgG excretion (P=0.0004), 24-h proteinuria (P=0.0067) and FE alpha(1)-m (P=0.0032) (R(2)=0.63). In 66 patients with NS and normal baseline renal function (MCD 10 patients; FSGS 20 patients; IMN 36 patients), according to values below or above defined cut-offs (IMN, 18 U/g urinary Cr; FSGS and MCD, 24 U/g urinary Cr), NAG excretion predicted remission in 86 vs 27% of IMN patients (P=0.0002) and 77 vs 14% of FSGS patients (P=0.005). Progression to chronic renal failure (CRF) was 0 vs 47% in IMN patients (P=0.001) and 8 vs 57% in FSGS patients (P=0.03). Using Cox model, in IMN patients only NAG excretion (P=0.01, RR 5.8), but not 24-h proteinuria, predicted progression to CRF. All MCD patients had NAG excretion values below the chosen cut-off, and 90% of them developed remission. Response to immunosuppressive therapy was significantly different in patients with NAG excretion values below or above the cut-offs. CONCLUSION: Urinary NAG excretion can be considered as a reliable marker of the tubulo-toxicity of proteinuria in the early stage of IMN, FSGS and MCD; the excretion values show a significant relationship with 24-h proteinuria, IgG excretion and FE alpha(1)m. Its determination may be a non-invasive, useful test for the early identification of patients who will subsequently develop CRF or clinical remission and responsiveness to therapy.