Viral Load Tests

The first diagnosis of your Hepatitis C was probably made due to the result of an (relatively cheap) anti-body test such as ELISA or similar. The result of this test was ' positive ', and that means that your body at some time has come into contact with the Hepatitis C virus and that the immune system of your body developed anti-bodies against this virus to fight this infection.

In order to find out, whether the virus is still active in your body, a different test has to be made: The presence of the virus has to be detected directly. For this purpose there are two types of tests available, the qualitative PCR test or a quantitative test.

The qualitative test can have only two results: Either the virus is detected, or the virus is not detected. If the virus is detected (result: positive), you know only that you do have the virus in your body, but you don't know in which quantity it is in your body. If no virus is detected (result: negative), you know that you either don't have the virus (any more), or that its concentration is so low that it cannot be detected.

The quantitative test on the other hand gives you a number for the Viral Load.

Your viral load is the amount of viruses present in a given volume of your blood More precisely, it means that the amount of Hep C genetic material found in your blood corresponds to as many Hep C viruses as the given number says. Therefore the given number denotes 'viral equivalents' (abbreviated: eq ).

The viral load can range from 'not detected' to hundreds of millions Hep C

viruses per milliliter, or up to near a hundred million IUs (International Units) per milliliter.

When you get back the result of your HCV RNA quantitative test, and when the lab was able to determine the amount of virus in your blood, then it is important to write down not only the number, but also in what units this number is given.

IT IS IMPERATIVE THAT YOU KEEP YOUR OWN RECORD EACH TIME YOUR BLOOD WORK IS DONE. Take control of your health.

The volume of blood that the number refers to is usually one milliliter (ml). But some labs give the number for 20 microlitres = 1/50 milliliter. So in these cases you have to multiply the result of the viral load by 50 to get the number for 1 milliliter.

Unfortunately, there are several ways to express the viral load. So, in order to be able to compare different results, you have to know how to convert these numbers to some standard format, which we would say is just the plain number of viruses per milliliter, like 1.5 Million/ml, or 1,500,000/ml. Thanks to the WHO, we now have another way to express the viral load, the IU (International Unit).

Giving the viral load in IU probably soon will replace all other ways to express the viral load - until recently it was expressed most frequently in eq or Meq. But at the moment and in old lab reports a wide variety of ways to give the viral load still can be found.

The IU = International Unit for the Hepatitis C viral load is a unit more or less arbitrarily fixed. Labs now can take part in international comparison tests using a calibrated sample and thereby normalize their results to an international standard. So, in the future results from different laboratories should be directly comparable.

For converting numbers from eq to IU and vice versa, different labs use different conversion factors, in the range from 2 to 5 viruses per IU. If you do not know the factor that your lab uses, using a factor of three might be reasonable. That means: Viral loads given in eq/ml have to be divided by three to get the viral load in IU/ml. And, viral loads given in IU/ml have to be multiplied by three to get the result in eq/ml.

Therefore it is important to have a close look at your lab report and see in what units the result is given 

If your test results are given to you in any form besides eq/ml, call your doctor’s office and have them convert the results for you.