Membranous nephropathy: when and how to treat

Independent or synergistic relationship of proteinuria and glomerular filtration rate on patient and renal survival in patients with glomerulonephritis?

BACKGROUND

Glomerular filtration rate (GFR) in patients with chronic kidney disease (CKD) identifies patients at risk for death or end-stage renal disease (ESRD). CKD staging by GFR should incorporate proteinuria to augment risk stratification. We therefore tested the predictive power of the combination of GFR with proteinuria in patients with different histologically-diagnosed types of glomerulonephritis (GN).

METHODS

In a retrospective analysis, 2,687 patients with different forms of GN from 123 Austrian centres were investigated. Full data sets were available from 1,892 subjects. Classes of CKD on the basis of estimated GFR (eGFR) and of proteinuria grouped as <1, 1-3.5, and >3.5 g/24 h were tested for their association with all-cause mortality and ESRD.

RESULTS

During a median follow-up of 130 months [interquartile range (IQR) 90; 178] 478 patients (25.3 %) died. Median eGFR was 49 ml/min/1.73 m(2) (IQR 24; 81) and proteinuria 3.8 g/24 h (IQR 1.7; 8.0). Adjusted multivariate Cox regression indicated that renal survival but not overall survival is related to proteinuria >3.5 g/24 h [as opposed to <1 g/24 h; hazard ratio (HR) 1.91] and shows progression to ESRD. However, subgroup analyses revealed that this risk with proteinuria >3.5 g/24 h exists only in patients with immunoglobulin (Ig)A GN (HR 4.93), miscellaneous GN (HR 1.74), and CKD stage 5 (HR 2.50). Additionally, proteinuria is a risk factor for renal survival in males more than in females with GN and proteinuria >3.5 g/24 h (HR 1.91).

CONCLUSION

Proteinuria is a strong risk factor for renal survival particularly in patients with proteinuria >3.5 g/24 but not for all types of GN, nor for all CKD stages. Proteinuria is not a risk factor for overall survival in patients with GN.

Impact of nephrotic edema of the lower limbs on obstructive sleep apnea: gathering a unifying concept for the pathogenetic role of nocturnal rostral fluid shift

BACKGROUND

Nocturnal rostral fluid shift has been suggested to be a risk factor for obstructive sleep apnea (OSA) in healthy subjects after lower body positive pressurization. It remains unclear whether this may apply to subjects with nephrotic lower limb edema and, if so, whether disease remission may reverse the accompanying OSA.

METHODS

Patients who presented with steroid-responsive primary nephrotic syndrome with lower limb edema as the predominant presenting clinical feature were recruited. They underwent one overnight polysomnography (PSG) before treatment and a repeat testing after achieving remission of the nephrotic edema.

RESULTS

Among 23 consecutive nephrotic subjects, 11 (48%) had polysomnographic evidence of sleep apnea [apnea-hypopnea index (AHI)≥5] upon presentation. After steroid-based treatment, there was remission of proteinuria associated with complete disappearance of lower limb edema, significant reduction of body mass index, waist, hip and calf circumferences and total body water mainly in the extracellular compartment. Repeat PSG, performed 8.1±2.6 months later, showed that the overall (N=23) respiratory disturbance index (RDI) and AHI fell from 17.3±5.0 to 8.7±2.5 (P<0.05) and from 16.3±5.1 to 7.8±2.3 (P=0.057), respectively. Among the 11 subjects with sleep apnea detected at baseline, their AHI and RDI fell from 33.4±7.8 to 15.0±3.7 (P<0.05) and from 34.8±7.6 to 16.5±4.0 (P<0.05), respectively. There was also concomitant improvement in sleep efficiency, mean nocturnal oxygen saturation, shorter duration during sleep with oxygen saturation<95 and <90% and reduced desaturation index. There was also subjective improvement in self-reported daytime sleepiness.

CONCLUSIONS

Nephrotic lower limb edema is associated with disturbed respiratory breathing and increased propensity to OSA, which was reversed upon remission of the nephrosis. This gathers a unifying concept for the role of nocturnal rostral fluid shift in the pathogenesis of OSA.

Tacrolimus combined with corticosteroids in treatment of nephrotic idiopathic membranous nephropathy: a multicenter randomized controlled trial

BACKGROUND

Idiopathic membranous nephropathy (IMN), a common cause of nephrotic syndrome in adults, is usually treated with corticosteroids in combination with cyclophosphamide or cyclosporine. A recent placebo-controlled study suggested that tacrolimus monotherapy was effective in IMN. However, the effectiveness of tacrolimus versus classic regimen and its potential nephrotoxicity remain inconclusive. This study evaluated the efficacy and safety of tacrolimus plus prednisone in patients with nephrotic IMN.

METHODS

Seventy-three patients with nephrotic IMN were recruited in this multicenter randomized controlled trial, 39 receiving tacrolimus and prednisone, while 34 receiving cyclophosphamide and prednisone. Tacrolimus was given at 0.1 mg/kg/d initially and adjusted to a blood trough level at 5 to 10 ng/mL for 6 months and then reduced to 2 to 5 ng/mL in the subsequent 3 months.

RESULTS

Intention-to-treat analysis suggested that the remission rate at the end of the sixth month was significantly higher in tacrolimus group than that in cyclophosphamide group (85% versus 65%, P < 0.05). The decrease of proteinuria was significantly greater in tacrolimus group. At the end of the 12th month, the remission rates were comparable between these 2 groups. Patients treated with tacrolimus were more likely to develop glucose intolerance (or diabetes mellitus), infection, and hypertension. No obvious nephrotoxicity of calcineurin inhibitor was found in repeat renal biopsy.

CONCLUSIONS

Tacrolimus plus corticosteroids is an alternative therapeutic regimen for nephrotic IMN. The short-term efficacy might be better than cyclophosphamide plus prednisone.

Idiopathic membranous nephropathy: management strategies

Treatment of idiopathic membranous nephropathy is based on a 'symptomatic' therapy that includes ACE inhibitors or angiotensin II receptor antagonists, and on an 'aetiological' therapy aimed at modulating underlying immunological mechanisms. The role of the latter is still debated given the usually indolent course of disease; furthermore, traditional immunosuppressants would not have an impact on patient and renal survival according to a systematic review of literature. However, up to 40% of untreated patients eventually develop end-stage renal disease and remission of nephrotic syndrome protects patients from related life-threatening complications and is the strongest positive prognostic factor for long-term kidney function. Therefore, immunosuppressive therapy seems to be rational in high-risk patients with nephrotic syndrome or deteriorating renal function. This article outlines a possible role for each 'aetiological' therapy on the basis of available evidence in order to provide some practical recommendations. The first-line therapy is based on a 6-month regimen of alternating corticosteroids and an alkylating agent ('Ponticelli' regimen), whereas oral ciclosporin and intramuscular corticotrophin (adrenocorticotrophic hormone) are alternatives that provide comparable results in terms of remission of proteinuria, with a different adverse effect profile. New drugs are emerging as potential treatments, such as mycophenolate mofetil, tacrolimus, intravenous immunoglobulins and rituximab. Specific settings, such as chronic renal failure or elderly age, require a careful balance between benefits and toxicity of immunosuppression. The tailor-made use of this repertoire of drugs can provide a tool to achieve remission of proteinuria and modify the natural course of idiopathic membranous nephropathy.

Membranous nephropathy in systemic lupus erythematosus: a therapeutic enigma

Renal disease is a major cause of mortality and morbidity in systemic lupus erythematosus. Among the histological classes of lupus nephritis, membranous nephropathy comprises only one-fifth of all cases. Reported survival and rates of end-stage renal disease in membranous lupus nephropathy (MLN) vary considerably, because of substantial heterogeneity among the published studies. The risk of progression from MLN to renal failure is generally reduced in the absence of proliferative lesions, but patients are, nevertheless, at risk of thromboembolic complications. The optimal therapy for MLN remains elusive because of a lack of controlled trials; however, cardiovascular protection and blockade of the renin-angiotensin system should be instituted early in all patients. Mixed membranous and proliferative lupus nephritis should be treated in the same way as pure proliferative lupus nephritis. If MLN is not accompanied by proliferative lesions but is associated with clinically relevant proteinuria, renal insufficiency or failure to respond to supportive therapies, immunosuppressive treatment is indicated. Treatment options include glucocorticoids combined with azathioprine, calcineurin inhibitors or alkylating agents. The efficacy of mycophenolate mofetil in MLN remains to be confirmed. Controlled trials to compare existing immunosuppressive agents and experimental modalities such as sirolimus, rituximab and infliximab should be undertaken in the future.

Idiopathic membranous nephropathy in pediatric patients: presentation, response to therapy, and long-term outcome

Background

Idiopathic membranous nephropathy (IMN) is one of the most common causes of primary nephrotic syndrome in adults. However, it is a relatively rare entity in the pediatric population and there is a paucity of data about the incidence, prognosis, and optimal treatment of IMN in children and adolescents. We conducted this study to evaluate pediatric patients with IMN in order to clarify the presentation, response to therapy, and clinical outcome.

Methods

A retrospective chart review was performed on patients identified with biopsy-proven IMN between 1988–2005. Patients with systemic lupus erythematosus or hepatitis-related lesions were excluded. The following data were tabulated: age, gender, ethnicity, presenting clinical and laboratory findings, proteinuria in a first morning urine specimen, estimated glomerular filtration rate (GFR_e), histopathology, type and duration of treatment, and clinical status at final evaluation.

Results

13 cases of IMN were identified out of 460 renal biopsies performed for evaluation of primary kidney disease during the study interval. Mean age was 9.6 ± 4.6, gender 6 M:7 F, ethnicity 8 W:2 B:3 H. At the initial visit hematuria was present in 9 patients, edema in 5, nephrotic-range proteinuria in 5, and hypertension in 3. Mean urinary protein:creatinine ratio 3.3 ± 2.5 and all patients had a normal GFR_e. Classic glomerular findings of IMN were seen in all renal specimens, with concomitant interstitial changes in 2 cases. Treatment included an angiotensin converting enzyme inhibitor or angiotensin receptor blocker in 11 cases. Most patients were also given immunosuppressive medications – prednisone in 10, a calcineurin inhibitor in 5, and mycophenolate mofetil or azathioprine in 3 patients. At the last follow-up, 42 ± 35 months after the diagnostic biopsy, 7 children were hypertensive and the urine protein:creatinine ratio was 2.3 ± 3.1. The mean GFR_e was 127 ± 57 mL/min/m². Three patients had Chronic Kidney Disease Stage 3, all of whom were also hypertensive.

Conclusion

IMN is a rare but serious glomerulopathy in pediatrics. We estimate that it accounts for approximately 3% of renal biopsies. Long-term prognosis is guarded because approximately 50% of patients may have evidence of progressive kidney disease.