Viral infections and the kidney

Hepatitis C and the kidney

Thanks to Dr. David Frost and Team 1 for presenting an interesting case in morning report today:

We discussed hepatitis C, and the various mechanisms of acute kidney injury specific to the infection. 

Our case had a sub-acute course of 6 weeks duration in which the creatinine increased from a baseline of 69 to 677 on the day of presentation.

We also discussed the importance of the physical exam, making sure to search for findings suggestive of fluid overload, which may push you towards dialysis, and also looking for specific findings of cryoglobulinemia (palpable purpura).  In any patient with acute renal failure, searching for findings that might lead to urgent dialysis is of high priority and so listening for pericardial rubs, and looking for signs of uremic encephalopathy (asterixis, decreased LOC) is important.

Investigations:

The initial investigations showed a normocytic anemia.  There was a non-anion gap metabolic acidosis with a normal potassium.  The liver enzymes and function tests were normal.  The blood film, looking for findings of HHS or TTP, did not show any schistocytes.

The urinalysis, also known as the physical exam of the kidney, showed 3+ protein, trace blood, and the microscopy showed heme-granular casts.  The urine sodium was 24.  The abdominal ultrasound did not show any hydronephrosis or ascites, and the kidneys were normal in size.

 

Viral infections and the kidney: HIV, hepatitis B, and hepatitis C. Appel, G. Cleveland Clinic Journal of Medicine. Volume 74. May 2007.

Discussion:

This interesting case brought up a differential diagnosis that is not commonly encountered, but general internists should have some idea of how to approach it, mainly the various renal manifestations of viral infections.

Many viruses can cause renal impairment, most notably HIV (HIVAN), Hepatitis B -membranous glomerulonephritis (GN), and Hepatitis C which causes a membranoproliferative GN (MPGN).

Viruses can damage the kidney through different mechanisms including immune complex deposition such as in the case of cryoglobulinemia, through direct cytotoxic effects, and also as a result of the antiviral medications themselves.

Hepatitis C and the kidney:

In the case of Hepatitis C, possibilities included MPGN, cryoglobulinemia, adverse effects of the medications, and in patients with cirrhosis then hepatorenal syndrome.

The treatment of MPGN related to cryoglobulinemia associated with Hepatitis C often involves plasmapheresis (PLEX) to remove the cryoglobulins, immunomodulatory medications (steroids), and treatment for the Hepatitis C virus itself (interferon, ribavirin).

As Dr. Frost nicely pointed out, the time honoured approach of pre-renal, renal, post-renal with regards to the diagnosis and management of acute kidney injury almost never fails.  I must admit, I was taught this approach by Dr. J. Bargman as a 2nd year medical student.  I use it to this day, and I believe it will still be taught well off into the future.

Please see the excellent paper below, which discusses various viruses and their effects on the kidney:

Reference:

Viral infections and the kidney: HIV, hepatitis B, and hepatitis C. Appel, G. Cleveland Clinic Journal of Medicine. Volume 74. May 2007.