Hepatitis induced kidney disease
Yes. Not every patient with HBV and HCV who develops kidney disease has a viral-induced glomerulopathy.
Because these viruses cause kidney disease due to viral replication, it is not surprising that advanced liver disease is usually present when they lead to glomerulonephritis.
Consequently, these patients often have portal hypertension and cirrhosis, which adds another differential diagnosis into the picture including hepatorenal syndrome (HRS).
Acute kidney injury in patients with cirrhosis is often related to prerenal azotemia from diuretics used for the mobilization of ascites and lower extremity edema, and at the extreme can result in HRS.
It is essential that physicians evaluating a patient with cirrhosis and known HBV or HCV who has developed acute kidney injury take into consideration the possibility of HRS. Differentiating HBV or HCV glomerulonephritis from HRS can be done using routine laboratory and urinalysis tests. The following questions should be asked:
• Is there proteinuria? Patients with HRS have less than 500 mg of protein excretion in 24 hours, as compared to patients with either hepatitis B- or C-related glomerulonephritis where the nephrotic syndrome is common.
• What does the urine sediment show? In patients with HRS, the urine sediment is bland with no cells or casts. In HCV-related MPGN, the urine will be nephritic with red-cell casts, dysmorphic red blood cells, white blood cells, and kidney tubular epithelial cells. In hepatitis B MN the urine will be nephrotic with fatty casts and oval fat bodies.
• Is the FENa (fractional excretion of sodium) helpful? Unfortunately, the FENa in patients with HRS or any form of glomerulonephritis will be less than 1%, indicating a sodium avid state. The FENa is not useful in differentiating between these diagnoses.
• What about serum complement levels? In HCV-related MPGN, the levels of C3 and C4 will be very low, indicating active consumption by the type II cryoglobulins, and the rheumatoid factor will be elevated. For HBV, MN, and HRS, the serum complement levels and rheumatoid factor will all be within normal limits.
