Investigations on the quantitative and qualitative protein excretion in urine of dogs with severe inflammatory response syndrome (SIRS)

AuszugProteins in the blood are subjected to the filtering and reabsorption processes of the renal glomeruli and tubules in such a way as to ensure that under physiological circumstances, the protein content in urine is quite minimal. Pathological levels of urinary protein excretion, known as proteinuria, occur when the renal mechanisms controlling protein passage are impaired. Proteinuria is classified based on the location of the pathology which leads to the presence of protein in the urine and therefore specific proteinuric patterns are characteristic for lesions in various areas of the nephron. Depending on the presence of proteins with certain molecular weights, it is possible to identify whether the renal lesions are mostly located in the glomeruli or the tubules and therefore whether filtration or reabsorption mechanisms are failing. In both dogs and humans, a variety of diseases and pathological conditions are known to cause proteinuria, the level and duration of which can be indicative of the severity of kidney damage. Severe Inflammatory Response Syndrome (SIRS) is observed in humans affected by trauma, surgery, burns and the critically ill. Despite intensive research in recent years, this highly prevalent syndrome is still accompanied by diagnostic and therapeutical challenges and a high mortality rate. During an extreme systemic inflammatory response, the unbalanced release of pro-inflammatory and anti-inflammatory cytokines as well as the resulting response of the immune system leads to the development of SIRS. Certain cytokines which circulate at high levels during the acute phase of SIRS are believed to cause changes in capillary permeability, the effects of which can be instrumental in the development of sepsis, severe sepsis, the failure of multiple organ systems and ultimately death. In this context, SIRS has been associated with acute renal failure in human patients. In recent years a number of studies have been conducted in human medical fields to explore possible early markers for the severity of SIRS. It is believed that SIRS induced increased capillary permeability leads to a transient increase in urinary protein content so that proteinuria has been suggested as an indicator of SIRS severity in humans. The prevalence and recognition of SIRS in critically ill canine patients has received increasing attention in recent years. Proteinuria has been reported to occur in a number of conditions in dogs and it is already widely in use as a diagnostic tool for a variety of diseases both renal and non-renal. However the occurrence of proteinuria within the framework of acute inflammatory response in dogs has received little attention. It can be hypothesized that in dogs, as with humans, SIRS will detrimentally affect the ability of the kidneys to properly maintain glomerular filtration and the reabsorption of proteins. It may also be possible to estimate the severity of the inflammatory response based on the level of urinary protein excretion so that a mortality prognosis can be made. The goal of this study therefore, was to investigate the occurrence and severity of proteinuria and to verify urinary biomarkers for the detection of both glomerular and tubular injury in dogs with SIRS. Furthermore the thesis aimed to elucidate whether associations can be drawn between proteinuria and mortality.