Hepatitis C Damage and Your Kidneys

You might want to have your kidneys tested if you have been diagnosed with Hep C

Kidneys
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In spite of its name, the disease hepatitis C ("hepatitis" indicating inflammation of the liver), is a multiorgan disease affecting organs beyond the liver. Chronic hepatitis C virus has the potential to affect wide-ranging organ systems, including the kidneys, the skin, the hematological system, and even cause autoimmune disease and diabetes. When it comes to the kidneys, hepatitis C tends to affect the "filter" of the kidneys, (called the "glomerulus") in various ways, creating different disease processes.

This realization that hepatitis C can have a major impact on kidney function and cause kidney disease is an essential take-home message, both for the physician managing the hepatitis C disease process, as well as for patients. It tells us that patients with hepatitis C should be evaluated for problems that might suggest kidney disease. Conversely, patients presenting to a nephrologist with certain signs or symptoms might need to be worked up for hepatitis C.

Hepatitis C and Kidney Damage

One frequent explanation for why hepatitis C disease affects the kidneys is the association between the hepatitis C virus and its tendency to incite inflammation in our blood vessels (something called "vasculitis"). This inflammation will frequently involve the kidney and has the potential to set off inflammatory reactions in the kidney's filter.

In other words, in most cases, it's not a direct infection of hepatitis C that hurts kidney function, but in fact the body's response to hepatitis C that does the damage.

Kidney function can then become "collateral damage" of a battle that rages between the hepatitis C virus and our body's immune system, with afflicted patients left with varying degrees of kidney disease.

What Does Hepatitis C Do to the Kidneys?

Once the above mechanisms have been set in motion, the kidneys begin to get damaged.

The most frequent site of damage is the kidney's filter, called the glomerulus (each kidney has a million of these tiny units). The reason this happens is because this filter is essentially a microscopic ball of tiny blood vessels. As mentioned above, hepatitis C virus does have a tendency to induce vasculitis, an immune injury to the blood vessels. Hence, this conglomeration of blood vessels inside the glomerulus is prone to a major hit.

Physicians typically divide hepatitis C-related kidney disease into the following categories:

  1. Mixed cryoglobulinemia – this is a specific type of inflammation of blood vessels/vasculitis. Blood vessels can be inflamed at various sites, not necessarily just in the kidneys. Hence, the affected patient could have symptoms ranging from kidney disease, to joint pains, to rash. If kidneys are affected, the patient might note blood in the urine, and a physician might be able to pick up protein (something which should normally not be present) on a urine specimen if the glomerulus has been significantly damaged.
  2. Polyarteritis nodosa – while classically associated with hepatitis B virus-mediated kidney damage, polyarteritis nodosa is now also reported with hepatitis C infection. This is a different kind of severe inflammation of the kidneys' blood vessels.
  1. Membranous nephropathy – the potential for hepatitis C to cause this entity is still not fully confirmed. We do know that hepatitis B virus can also induce this change in the kidneys' filter.

How Would One With Hep C Know They Have Kidney Disease?

You might not! Beyond the symptoms of hepatitis C, kidney-specific symptoms may or may not be present and it's not unusual to have silent disease, unbeknownst to the patient. As described above, patients could see blood in the urine, but that might not always be the case. Similarly, protein in the urine might not be apparent (or present as nonspecific "foam in the urine"), or be attributed to other ailments that you might have (like hypertension or diabetes).

Needless to say, none of these findings are enough to confirm or refute hepatitis C-related kidney damage. However, a good physician will order tests of the kidneys' function (like serum creatinine, GFR, etc) in a patient with hepatitis C, while a nephrologist managing a patient with any of the above telltale features should start looking for hepatitis C as a potential cause. Specifically, there are a few other tests which could be helpful:

  • Testing for something called "cryoglobulins."
  • Rheumatoid factor testing
  • Testing the Complement levels

Since the disease happens at a microscopic level and can come in different "flavors," a kidney biopsy is often the only way to confirm what is going on.

Kidney Disease From Hep C Treatment

In a nutshell, treat the cause. Hence, in those found to have severe kidney damage which could be causally linked to hepatitis C, the treatment should focus on treating hepatitis C. However, it's not always that straightforward. Not every patient with hepatitis C is necessarily a candidate for treatment since response rates vary and the side effects of therapy have to be kept in mind.

Certain patients could already be past the "point of no return" when it comes to both salvaging liver or kidney function. Kidneys especially tend to not have much of a regenerative capacity. Hence, if severe scarring has already occurred in the kidneys, it's unlikely that the patient would recover kidney function even with treatment of hepatitis C. Regardless, there could be perfectly valid reasons (for the sake of liver and other organs), to still treat hepatitis C.

An important point to remember is that the presence of kidney disease itself changes treatment choices for hepatitis C as well. This is because therapy is often different based on the level of kidney damage. Talk to your doctor about the best treatment path for you.

Sources:

N Perico, D Cattaneo, B Bikbov, G Remuzzi. Hepatitis C Infection and Chronic Renal Diseases. CJASN January 2009 vol. 4 no. 1 207-220.

Patrice Cacoub, MD. Extrahepatic manifestations of chronic hepatitis C virus infection. Ther Adv Infect Dis. 2016 Feb; 3(1): 3–14.

HCV Guidance: Recommendations for Testing, Managing, and Treating Hepatitis C. American Association for the Study of Liver Diseases and the Infectious Diseases Society of America.

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