[Instructions and implementations for percutaneous renal biopsy. Guidelines for the therapy of glomerular nephropaties]

Abstract

This series of articles on the management of glomerulonephritis (GN) has been prepared by a team of experts in the evidence-based format consistent with peer review of published data. Each author was asked to review the literature for his assigned histological type, with emphasis on therapy and limited to adult studies. The age limit was not considered for minimal change disease and focal segmental glomerulosclerosis, because of the high prevalence of these glomerulopathies in children. The particular treatment recommendations for each type of glomerular disease were graded by each author according to the amount of evidence provided in these reviewed studies. The first two articles concentrate on indications and techniques for kidney biopsy. Each subsequent article focuses on and describes the highest level of evidence supporting the recommendation for therapy in IgA nephropathy (Ig-GN), minimal change nephropathy (MCN) and focal segmental glomerulosclerosis (FSGS), membranous glomerulonephritis (MGN), lupus nephritis, ANCA-associated vasculitis, HCV-associated cryoglobulinaemia and renal involvement in paraproteinemic disorders. The article on IgA nephropathy emphasises the importance of carefully evaluating both clinical and histologic findings before settling on the treatment. The recent, renewed interest in steroids and many immunosuppressive agents is discussed in detail. Recommendations related to the patient's age are also provided. MCN and FSGS are treated together because these forms share similar evidence-based recommendations. For both of these diseases, in fact, the initial treatment approach in children should be prednisone or prednisolone for four to six weeks. The therapeutic response in adults is slower than in children, but adults experience fewer relapses and a more prolonged remission. There is also a discussion on treatment of relapse, frequent relapsing disease and true steroid-resistant disease as well as the role of new immunosuppressive agents. Membranous nephropathy is a frequent cause of nephrotic syndrome in adults and, in one third of these patients, leads to end-stage renal disease. However, the treatment of this form is as yet a matter of discussion. Based on extensive critical review of the literature, the following recommendations are put forward: (a) no treatment in the absence of nephrotic syndrome; (b) patients with heavy proteinuria should receive a 6-month treatment with i.v. methylprednisolone (MP) pulse therapy for three consecutive days followed by oral MP (0.4 mg/kg/day) (months 1, 3, 5) and chlorambucil or cyclophosphamide (months 2, 4, 6); (c) the dosage of chlorambucil or cyclophosphamide should be lowered in older patients; (d) cyclosporine is a second-choice treatment. The treatment of lupus nephritis depends on the histologic class. No specific treatment is usually necessary for class I and IIA. Oral steroids are indicated in patients with class IIb, proteinuria and active systemic disease. Steroids and azathioprine are the treatment of choice for patients with class III and IV, but cyclosporine can be an effective alternative therapy. Cyclophosphamide is more effective than azathioprine when severe acute renal involvement is present. The treatment of ANCA-associated vasculitis depends mainly on clinical presentation, oral prednisone + oral or i.v. cyclophosphamide are generally effective. In the most severe cases, the association of MP pulse therapy with cyclophosphamide is probably more effective. Plasma exchange is probably justified in unresponsive patients. Azathioprine should replace cyclophosphamide during the maintenance therapy. In HCV-associated mixed cryoglobulinemia the treatment also depends on the severity of renal involvement. The treatment for chronic HCV infection involves alpha interferon alone or preferably in combination with ribavirin. Aggressive therapy, including i.v. MP, plasmapheresis and cyclophosphamide is primarily reserved for patients with acute severe disease, as manifested by progressive renal failure, distal necroses requiring amputation, or advanced neuropathy. Uncontrolled studies suggest that this regimen can improve renal function. Renal involvement is a common problem in paraproteinemic disorders that include multiple myeloma, Waldentrom's macroglobulinaemia and monoclonal gammopathy. The most common renal diseases in this setting are cast nephropathy, primary amyloidosis cast nephropathy, primary amyloidosis, and light chain deposition disease that are related to the overproduction of monoclonal immunoglobulin light chains. The approach to therapy varies with the cause of the renal dysfunction. Patients with amyloidosis or light-chain deposition disease are generally treated with chemotherapy, but the most effective therapy for myeloma kidney is prevention by minimising the risk factors that promote light chain filtration and subsequent obstruction by cast formation within the tubules. Chemotherapy or stem cell or bone marrow transplantation to decrease filtered light chain load, prevent volume depletion and maintain high fluid intake to reduce light chain concentration within the tubular lumen are indicated in almost all the patients.