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The histopathological term focal-segmental glomerulosclerosis comprises different pathogenic processes with the unifying features of a high proteinuria and the name-giving glomerular lesion pattern seen on light microscopy. A differentiation according to the underlying cause into primary, secondary and genetic forms is therefore of utmost importance. The pathogenesis of primary focal-segmental glomerulosclerosis remains unknown but, like minimal-change disease, an autoimmune-mediated process leading to podocyte damage is assumed. Consequently, the unifying term "podocytopathy" is increasingly being used for both entities. Supportive treatment measures to preserve kidney function are important in all subtypes. In contrast, immunosuppressive treatment is only indicated in primary focal-segmental glomerulosclerosis. Steroid-dependence, steroid-resistance and frequently relapsing disease often complicate disease management and necessitate alternative treatment strategies. Here, the Austrian Society of Nephrology (ÖGN) provides consensus recommendations on how to best diagnose and manage patients with focal-segmental glomerulosclerosis., (© 2023. The Author(s).)

If proteinuria is of sufficient amount, and persists for long enough, then a series of consequences arises which is called the nephrotic syndrome. The most notable consequence of massive proteinuria is salt and water retention leading to edema formation. This edema is found in association with proteinuria usually greater than 3.5 g/day, accompanied by hypoalbuminemia, usually less than 25 g/l. The underlying disease is usually a glomerulonephritis, albeit in rare situations severe renal artery stenosis can lead to proteinuria by hyperfiltration. Two theories have been proposed. In the classical "underfill" theory edema is considered to be secondary to salt retention resulting from renal hypoperfusion. According to this theory the primary event is the decrease in plasma volume due to the diminution of plasma oncotic pressure resulting from hypoalbuminemia, causing transfer of fluid from the plasma to the interstitial space "underfilling" the blood compartment and resulting to secondary renal sodium retention. This mechanism applies mainly to the nephrotic syndrome associated with minimal change disease observed in children. By contrast, in most adults with the nephrotic syndrome due to minimal change disease or other glomerular lesions such as membranous or proliferative glomerulonephritis, an initial plasma volume expansion is observed. Therefore, the primary event responsible for the sodium retention is a renal intrinsic excretory defect, which leads to extracellular fluid expansion and edema formation. Therapy is specific for the specific glomerular disease and symptomatic for the edema (diuretics), anticoagulation therapy for prevention of venous thrombosis and embolism, antibiotics for infections, and most of all, omission of triggering factors such as specific xenobiotics.

Recent progress in defining the genetic basis of inherited glomerular diseases has provided a completely new understanding of the glomerular filter of the kidney and has helped illuminate the pathogenesis of acquired and inherited renal proteinuric diseases. Based on the findings of molecular genetics in nephrology we will discuss the current understanding of the glomerular filter and provide an idea how genetic testing in the future may help to guide therapy in patients suffering from nephrotic syndrome and progressive renal failure.

History and Clinical Findings: An 82-year-old woman with hypertension for 20 years developed a nephrotic syndrome with severe oedema followed by acute oliguric renal failure after a bout of bronchitis and a gastrointestinal infection. She also complained of xerostomia and dry eyes of recent onset., Investigations: Biochemical tests showed a serum creatinine level of 6.1 mg/dl, a 1:5120 antinuclear antibody (ANA) titre, and positive values for Ro(SS-A) and La(SS-B) antibodies. HLA-DR typing demonstrated HLA-DR3 (HLA-DRB1*0301) and DR13 (HLA-DRB1*13) antigens. Renal biopsy revealed minimal glomerular lesions with focal and segmental glomerulo-sclerosis as well as (hypertension-induced) benign nephrosclerosis and focal tubular atrophy with interstitial fibrosis., Treatment and Course: After two hemofiltrations and concomitant administration of 100 mg prednisone renal function quickly improved and the proteinuria fell to 1 g/dl. At the same time the xerostomia improved. The nephrotic syndrome recurred 7 months later after the prednisone dose had been reduced to 10 mg/d, but after the dose had been raised to 50 mg/d and cyclosporin A (150 mg/d) had been added a lasting remission occurred and renal function became stable though impaired., Conclusion: The relatively rare association of glomerular disease (here focal segmental glomerulosclerosis) with Sjögren's syndrome can, as in this case, be triggered by a viral infection. A genetic predisposition for Sjögren's syndrome is suggested by the demonstration of HLA-DR3 alleles. Administration of steroids is indicated for the treatment of the nephrotic syndrome and, in case of recurrence, can be combined with cyclosporin A. Both drugs also influence the symptoms of Sjögren's syndrome.

We describe the frist reported case in Switzerland of HIV-associated nephropathy (HIVAN). HIVAN shows a typical combination of clinical findings: black race, proteinuria, large hyper-echogenic kidneys, normal blood pressure, positive HIV serology and no autoantibodies. The histologic findings are typical: focal segmental glomerulosclerosis of the collapsing variant, often with marked interstitial nephritis. The disease normally appears before AIDS symptoms develop and follows a very aggressive course to end-stage renal disease. Therapy consists of a combination of nucleoside reverse transcriptase and proteinase inhibitors, ACE inhibitors, and possibly steroids. In end-stage renal disease patients can be managed by haemodialysis, continuous ambulatory peritoneal dialysis (CAPD) or kidney transplantation.

Dyslipidemia is a common feature of renal failure. It is primarily caused by delayed catabolism of lipoprotein particles. This is due to decreased activity of the key enzymes of delipidation of lipoprotein particles (LPL, HTGL) and of HDL remodeling (LCAT). In epidemiological studies no correlation has been found in dialysis patients between total lipids and atherosclerotic endpoints and a modest relation, at best, between more sophisticated apolipoprotein indices and vascular disease. Such lack of correlations are presumably explained by malnutrition as a confounding factor. Fascinating new observations in animal studies document that in various models of renal damage, development of glomerulosclerosis is accelerated by hyperlipoproteinemia, either endogenous hyperlipoproteinemia or hyperlipoproteinemia induced by feeding of fat. Conversely, correction of hyperlipoproteinemia mitigates development of glomerulosclerosis. Currently there is no firm evidence that the same is true in humans.

The effect of immunosuppressive agents in different glomerulopathies is reviewed and some guidelines for their use in clinical practice are proposed. The immunological aspects of pyelonephritis and interstitial nephritis are studied to evaluate future possibilities of either therapeutic immunosuppression or immunization in these diseases.