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Hepatorenal syndrome

2007 Schools Wikipedia Selection. Related subjects: Health and medicine

   CAPTION: Hepatorenal syndrome
   Classifications and external resources

     ICD- 10   K767
     ICD- 9    572.4
   DiseasesDB  5810
   MedlinePlus 000489
    eMedicine  med/1001

   Hepatorenal syndrome (HRS) refers to acute renal failure that occurs in
   the setting of cirrhosis or fulminant liver failure associated with
   portal hypertension, usually in the absence of other disease of the
   kidney. The pathology involved in the development of hepatorenal
   syndrome is thought to be an alteration in blood flow and blood vessel
   tone in the circulation that supplies the intestines (the splanchnic
   circulation) and the circulation that supplies the kidney. It is
   usually indicative of an end-stage of perfusion, or blood flow to the
   kidney, due to deteriorating liver function. Patients with hepatorenal
   syndrome are very ill, and, if untreated, the condition is usually
   fatal. Treatment usually involves medical therapy or TIPS as a bridge
   to liver transplantation.

Definition and clinical presentation

   The hepatorenal syndrome is defined as renal failure that occurs in the
   setting of liver disease as follows :
     * Type I HRS, which is characterized by rapidly progressive renal
       failure with a doubling of serum creatinine to a level greater than
       221 μmol/L (2.5 mg/ dL) or a halving of the creatinine clearance to
       less than 20 mL/min over a period of less than 2 weeks. Type I HRS
       carries a very poor prognosis, usually of less than 50% over one
       month. Patients with type I hepatorenal syndrome are usually ill,
       may have low blood pressures, and may require therapy with
       inotropes, or intravenous drugs to maintain blood pressure.

     * Type II HRS, which is characterized by a slowly progressive
       increase in serum creatinine level to greater than 133 μmol/L (1.5
       mg/dL) or a creatinine clearance of less than 40 mL/min. It is
       typically associated with ascites that is unresponsive to diuretic
       medications, and also carries a poor, if somewhat longer (median
       survival ~6 months) outlook, unless the patient undergoes liver
       transplantation.

   It can be challenging to distinguish hepatorenal syndrome from other
   entities that cause renal failure in the setting of advanced liver
   disease. As a result, additional major and minor criteria have been
   proposed to assist in the diagnosis of the hepatorenal syndrome.

   The major criteria include liver disease in the setting of portal
   hypertension; renal failure; the absence of shock, infection, recent
   treatment with medications that affect the kidney's function (
   nephrotoxins), and fluid losses; the absence of sustained improvement
   in renal function despite treatment with 1.5 litres of intravenous
   normal saline; the absence of proteinuria, or protein in the urine;
   and, the absence of renal disease or obstruction of renal outflow as
   seen on ultrasound.

   The minor criteria are laboratory in nature, and include a low urine
   volume (less than 500 cc per day), low sodium concentration in the
   urine, a urine osmolality that is greater than that in the blood, the
   absence of red blood cells in the urine, and a serum sodium
   concentration of less than 130 mmol/L.

Similar conditions

   Many other diseases of the kidney are associated with liver disease and
   must be excluded before making a diagnosis of hepatorenal syndrome.
   They include the following:
     * Pre-renal failure: Pre-renal failure usually responds to treatment
       with intravenous fluids, resulting in reduction in serum creatinine
       and the excretion of sodium.
     * Acute tubular necrosis (ATN): This can be difficult to confidently
       diagnose. It may be an inability to concentrate the urine, if any
       is being produced. The urine sediment should be bland, microscopy
       may show hyaline casts. ATN may recover with supportive treatment
       only or progress to end-stage renal failure. In cirrhosis, urinary
       sodium is not a reliable guide to the development of ATN, as
       fractional sodium excretion may stay below 1 percent, due to the
       gradual worsening of renal ischaemia.
     * Other causes may include glomerular disease secondary to Hepatitis
       B or Hepatitis C, drug toxicity (notably gentamicin) or contrast
       nephropathy.

Pathophysiology

   The renal failure in hepatorenal syndrome is believed to arise from
   abnormalities in blood vessel tone in the splanchnic circulation (which
   supplies the intestines). It is known that there is an overall
   decreased systemic vascular resistance in hepatorenal syndrome, but
   that the measured femoral and renal fractions of cardiac output are
   respectively increased and reduced, suggesting that splanchnic
   vasodilation is implicated in the renal failure.

   There is activation of the renin-angiotensin-aldosterone system (RAAS)
   and the sympathetic nervous system, and profound vasoconstriction of
   the kidneys. Many vasocontrictor chemicals have been hypothesized as
   being involved in this pathway, including vasopressin, prostacyclin,
   thromboxane A2,, and endotoxin.

Epidemiology

   It is estimated that 39% of patients with cirrhosis and ascites will
   develop hepatorenal syndrome within five years of the onset of their
   disease. The prognosis of these patients is grim with untreated
   patients having an extremely short survival, and with the severity of
   liver disease (as evidenced by the MELD score) now believed to
   determine outcome. Some patients without cirrhosis develop hepatorenal
   syndrome, with an incidence of about 20% seen in one study of ill
   patients with alcoholic hepatitis.

Treatment

   Because of the high mortality associated with hepatorenal syndrome,
   emphasis is on prevention in patients who are at risk for the
   condition. Strategies for avoiding hepatorenal syndrome include
   appropriate and non-aggressive use of diuretics, identification and
   early treatment of infection and hemorrhage, and avoidance of other
   toxins that can affect both the liver and kidney.

   The definitive treatment for hepatorenal syndrome is liver
   transplantation, and all other therapies can best be described as
   bridges to transplantation. These treatment strategies include the
   following:
     * Midodrine and octreotide: Midodrine is an alpha-agonist and
       octreotide is an analogue of somatostatin. The medications are
       respectively systemic vasoconstrictors and inhibitors of
       vasodilators, and were not found to be useful when used
       individually in treatment of hepatorenal syndrome. However, one
       study of 13 patients with hepatorenal syndrome showed significant
       improvement when the two were used together (with midodrine given
       orally, octreotide given subcutaneously and both dosed according to
       blood pressure), with three patients surviving to discharge.
     * Vasopressin analogues: Ornipressin was found in a number of studies
       to be useful in improvement of renal function in patients with
       hepatorenal syndrome, but has been limited by ischemic
       complications . Terlipressin is a vasopressin analogue that has
       been found in one study to be useful for improving renal function
       in patients with hepatorenal syndrome with a lesser incidence of
       ischemia. Neither medication is available for use in North America.
     * Albumin: All major studies showing improvement in renal function in
       patients with hepatorenal syndrome have involved expansion of the
       volume of the plasma with albumin given intravenously
     * Transjugular intrahepatic portosystemic shunts (TIPS) involve
       decompression of the high pressures in the portal circulation by
       placing a small stent between a portal and hepatic vein. They have
       also been shown to improve renal function in patients with
       hepatorenal syndrome.
     * Liver dialysis involves extracorporeal dialysis to remove toxins
       from the circulation. The molecular adsorbents recirculation system
       (MARS) has shown some utility as a bridge to transplantation in
       patients with hepatorenal syndrome.
     * Renal replacement therapy may be required to 'bridge' the patient
       to liver transplantation, although the condition of the patient may
       dictate the modality used.
     * Other agents used in treatment include pentoxifylline,
       acetylcysteine, and misoprostol.

History

   Historically, the hepatorenal syndrome was first defined as acute renal
   failure that occurred in the setting of biliary surgery. The syndrome
   was soon associated with advanced liver disease. It was determined that
   kidneys transplanted from patients with hepatorenal syndrome were
   functional, leading to the hypothesis that hepatorenal syndrome was a
   systemic as opposed to renal disease.

Quotable Quotes

"The liver and kidney are the greatest of lovers.When the liver is diseased the
kidney weeps" - Dr (Col)S.Krishnan, M.D.(Pune),D.M.(Chandigarh),Apollo Hospitals
,Chennai,India

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