Tuesday, 26 August 2008

What is the hepatorenal syndrome?

The hepatorenal syndrome occurs in up to 10% of advanced cases of liver cirrhosis with ascites, and is characterised by renal failure due to severe vasoconstriction of the renal circulation. As you know, in liver failure there is underfilling of the arterial circulation from a combination of splanchnic vasodilatation and hypoalbuminaemia. The body attempts to compensate by retaining sodium and water at the kidneys, and by constricting its arterioles generally.

Unfortunately, the delicate kidneys suffer greatly from this vasoconstriction of their circulation, and end up exhibiting signs of failure. Hepatorenal syndrome may be further divided up into two types based on the pattern of decline. In type 1, there is rapid deterioration - if an initial serum creatinine is over 2.5 mg/dl (221 ┬Ámol/l), this figure will double within two weeks. These patients have a median survival of less than one month without therapy. Type 2 is slightly more benign, with its decline progressing more slowly than in type 1.

Treatment usually centres around vasoconstrictor drugs, in combination with albumin (although other modalities, like transjugular intrahepatic portosystemic shunts, have been tried too). Vasoconstrictor plus albumin treatment is effective in two thirds of these patients. It might seem a little odd to be treating with vasoconstrictors, seeing as I defined hepatorenal syndrome as being due to vasoconstriction! However, the primary haemodynamic problem in cirrhosis is the splanchnic vasodilatation (more on this here) - it's this vasodilatation that causes the compensatory systemic vasoconstriction that causes the hepatorenal syndrome in turn. Giving the body a little help with vasoconstrictors and albumin actually causes a net increase in renal perfusion, and thus helps resolve the hepatorenal syndrome.

The recommendation at present is to try the above therapy for 5-15 days, until the serum creatinine concentration drops to below 1.5 mg/dl (about 133 ┬Ámol/l). Recurrence of this syndrome is rare after this regimen, and patients who respond to it tend to live longer.

Main source: Gines P, Cardenas A, Arroyo V, Rodes J. Management of Cirrhosis and Ascites. NEJM 2004;350;1646-54

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