Preface

Chronic kidney disease (CKD) is a worldwide disease affecting up to 4% of the population with increasing figures also in developing countries. Life expectancy of patients affected by CKD is shortened compared to the overall population and only a minority of the patients reaches end-stage renal disease with the need for dialysis or renal transplantation; death overtakes dialysis. In many cases, glomerulonephritis is the underlying disease leading to kidney failure. One hallmark of glomerulonephritis is proteinuria, which may in its most severe form lead to nephrotic syndrome. Clinically, the syndrome presents with massive proteinuria, hypoalbuminuria, edema, and hyperlipidemia. In children, idiopathic nephrotic syndrome is the commonest manifestation of glomerular disease. Although the genetics of congenital forms are well known to the pediatrician, secondary forms of nephrotic syndrome caused by different types of glomerulonephritis are encountered. The etiopathogenesis of nephrotic syndrome has evolved over several years and theories. Now, podocyte injury is thought to be the keystone in the pathology of different forms of glomerulonephritis associated with massive proteinuria. Therefore, one chapter aims to highlight the mechanisms underlying the pathogenesis of nephrotic syndrome as a podocytopathy, especially in children.

But also in adults, nephrotic syndrome caused by different types of glomerulonephritis occurs. One form of glomerulonephritis of special interest is membranous nephropathy. In non-diabetic Caucasian adults, membranous nephropathy is the leading cause of nephrotic syndrome. There, membranous nephropathy is most often primary (idiopathic) and the remaining is secondary to systemic disease or exposure to infection or drugs. The therapeutic approach reaches from supportive care to immunosuppressive protocols, always trying to minimize proteinuria.

Three chapters of this book focus on membranous nephropathy. There is a fine and concise review of the epidemiology, diagnosis, and treatment of membranous nephropathy, particularly focusing on idiopathic membranous nephropathy. Another chapter strengthens the aspect of membranous nephropathy as an autoimmune disease, aiming to increase our current understanding of autoimmune membranous nephropathy and use it as a basis for the understanding of autoimmune disease in general.

One important clinical aspect in patients with nephrotic syndrome, especially in membranous nephropathy, is increased risk for venous thrombosis. Hypercoagulopathy as a result of the loss of antithrombotic factors such as antithrombin III and plasminogen due to proteinuria, an increased level of factor VIII and fibrinogen, along with increased platelet reactivity have been noted in nephrotic syndrome whatever the cause. However, compared to other conditions that have a similar degree of proteinuria, membranous nephropathy has a higher risk of venous thrombosis and its associated risks.

Interestingly, many patients with membranous nephropathy have circulating antibodies to different podocyte antigens, and immunologic remission (depletion of PLA2R antibodies) often precedes and may predict clinical remission. The use

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**Section 4**

Renal Rehabilitation **101**

**Chapter 7 103**

Renal Rehabilitation: A Perspective From Human Body Movement *by Jorge Enrique Moreno Collazos and Diana Carolina Zona Rubio*

of biomarkers in glomerular diseases is not restricted to membranous nephropathy. Biomarkers provide worthwhile evidence in diagnosis, guide treatment strategies, and give information about prognostic aspects. The importance of several substances and molecules, such as inflammatory cells, autoantibodies, cytokines, chemokines, and growth factors and their role as potential biomarkers, is also described in this book.

Although our knowledge of renal disease has grown, and dialysis treatment is available worldwide, we do not know to what extent low physical activity, uremia, and anemia determine the decrease in functional capacity of patients on dialysis. Therefore, the final chapter of the book will focus on the aspects of rehabilitation in patients with severe kidney disease.

This book comprises a total of seven chapters from authors and researchers from different countries and continents, thus reflecting the worldwide importance of CKD.

We are grateful to all the contributors and experts for the preparation and submission of their stimulating manuscripts. And, last but not least, many thanks go to the team of IntechOpen who gave us the opportunity to publish all these very interesting papers and thoughts in a peer-reviewed Open Access book.

> **Thomas Rath** Department of Nephrology and Transplantation Medicine, Westpfalz-Klinikum, Kaiserslautern, Germany

Section 1

Measuring Kidney Function

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Section 1
