Hepatorenal Syndrome

Hepatorenal Syndrome (HRS) is an important condition for clinicians to be aware of in the presence of cirrhosis. In simple terms, HRS is defined as a relative rise in creatinine and relative drop in serum glomerular filtration rate (GFR) alongside renal plasma flow (RPF) in the absence of other competing etiologies of acute kidney injury (AKI) in patients with hepatic cirrhosis. It represents the end stage complication of decompensated cirrhosis in the presence of severe portal hypertension, in the absence of prerenal azotemia, acute tubular necrosis or others. It is a diagnosis of exclusion. The recognition of HRS is of paramount importance for clinicians as it carries a high mortality rate and is an indication for transplantation. Recent advances in understanding the pathophysiology of the disease improved treatment approaches, but the overall prognosis remains poor, with Type I HRS having an average survival under 2 weeks. Generally speaking, AKI and renal failure in cirrhotic patients carry a very high mortality rate, with up to 60% mortality rate for patients with renal failure and cirrhosis and 86.6% of overall mortality rates of patients admitted to the intensive care unit. Of the various etiologies of renal failure in cirrhosis, HRS carries a poor prognosis among cirrhotic patients with acute kidney injury. HRS continues to pose a diagnostic challenge. AKI can be either pre-renal, intrarenal or postrenal. Prerenal causes include hypovolemia, infection, use of vasodilators and functional due to decreased blood flow to the kidney, intra-renal such as glomerulopathy, acute tubular necrosis and post-renal such as obstruction. Patients with cirrhosis are susceptible to developing renal impairment. HRS may be classified as Type 1 or rapidly progressive disease, and Type 2 or slowly progressive disease. There are other types of HRS, but this chapter will focus on Type 1 HRS and Type 2 HRS. HRS is considered a functional etiology of acute kidney injury as there is an apparent lack of nephrological parenchymal damage. It is one several possibilities for acute kidney injury in patients with both acute and chronic liver disease. Acute kidney injury (AKI) is one of the most severe complications that could occur with cirrhosis. Up to 50% of hospitalized patients with cirrhosis can suffer from acute kidney injury, and as mentioned earlier an AKI in the presence of cirrhosis in a hospitalized patient has been associated with nearly a 3.5-fold increase in mortality. The definition of HRS will be discussed in this chapter, but it is characterized specifically as a form of acute kidney injury that occurs in patients with advanced liver cirrhosis which results in a reduction in renal blood flow, unresponsive to fluids this occurs in the setting of portal hypertension and splanchnic vasodilation. This chapter will discuss the incidence of HRS, recognizing HRS, focusing mainly on HRS Type I and Type II, recognizing competing etiologies of renal impairment in cirrhotic patients, and the management HRS.