The first test doctors usually order is the hepatitis C antibody test.

Your immune system makes special proteins when harmful foreign microorganisms like bacteria, fungi, parasites, and viruses enter your body. These special proteins are called antibodies. The human body makes millions of different antibodies. Each one is tailored to fight a particular microorganism you’ve been exposed to.

The antibodies try to neutralize or destroy the foreign invader before it can do harm. Hepatitis C antibodies are made by white blood cells and attack only the hepatitis C virus. They bind to the virus and set it up for attack by other parts of the immune system.

The hepatitis C antibody test is a blood test that looks for hepatitis C antibodies in the bloodstream. A positive result usually means that you’ve been exposed to the hepatitis C virus. A positive result can occasionally be a false positive.

A negative result means that no antibodies have been detected in your bloodstream. This could indicate that there is no infection or you were exposed so recently that not enough antibodies have built up yet to be detectable. Or it could be a false negative.

It’s also possible to get an indeterminate result from this test.

If you’re in a high-risk group but tested negative, your doctor may have you repeat the test to make sure it wasn’t a false negative. If you test positive but your doctor thinks it’s unlikely that you have hepatitis C, they may have you repeat the test as well.

Having hepatitis C antibodies in your bloodstream only indicates that you had the infection at one time. It doesn’t tell your doctor if the infection is currently active or not.

Hepatitis C is a virus that attacks the human liver. It causes damage and, over time, destroys the liver by killing off healthy cells. The virus leaves tough scar tissue behind which keeps the liver from working properly.

There are several tests that doctors order to check for the hepatitis C virus. The earlier it’s caught and treated, the less damage the virus can do to your liver. Your liver serves many important functions, including:

  • filtering toxins out of your blood
  • processing sugar, cholesterol, and iron
  • producing bile to help digest food

Approximately 15 to 25 percent of people infected by the hepatitis C virus clear it from their bodies without treatment, according to the Centers for Disease Control and Prevention (CDC). Others will develop liver scarring. Without treatment, this can progress to cirrhosis (a state where the liver is so scarred it can barely function), liver failure, or liver cancer over time.

Treatments are available that can help many people with hepatitis C, so it’s important to get tested if there’s a chance that you’ve been exposed to the virus.

If hepatitis C antibodies are found in your bloodstream, your doctor will order an RNA test to find out whether the infection is active. If it is, a genotyping test will pinpoint what type of hepatitis C you have.

RNA tests

In order to tell if you have an active infection, your doctor will order a hepatitis C RNA quantitative test. This test looks for viral ribonucleic acid (RNA) inside the virus cells in your bloodstream. You have an active hepatitis C infection if the test finds viral RNA.

The same test measures the amount of viral RNA in your blood before and during treatment. It’s used to determine how well your treatment is working.

Genotyping test

There are six types of hepatitis C. Each type, or genotype, represents a specific combination of genes within a cell. The hepatitis C genotyping test shows which genotype of hepatitis C must be treated.

Genotype 1 is the most common genotype, according to the CDC. About 70 to 75 percent of people who have hepatitis C have genotype 1.

Genotype 2 accounts for 13 to 15 percent of people with hepatitis C. About 10 percent have genotype 3. Genotypes 4, 5, and 6 are rare.

Each hepatitis C genotype represents a genetically distinct group of the virus. Each responds differently to treatment. Doctors tailor your treatment to match the genotype of the virus. This helps to predict how long your treatment should last and what your outcome should be.

Hepatitis C is contagious, but it can only be passed to another person by sexual contact or blood contact through a break in the skin or through the mucous membranes. You can’t get hepatitis C from any of the following:

  • sharing eating utensils
  • breastfeeding
  • hugging, kissing, or holding hands
  • coughing or sneezing
  • through food or water

You should be tested for hepatitis C if you:

  • have used a needle to inject drugs or have shared drug equipment
  • had a blood transfusion or organ transplant before 1992 or clotting factors before 1987
  • are a healthcare worker who’s had a needlestick injury
  • have tattoos or body piercings done in unclean settings (with unsterilized instruments)
  • have had a sexual partner with hepatitis C, now or in the past (A recent study shows that it’s rare to get hepatitis C this way.)
  • were born to a mother who has hepatitis C

Be sure to get tested if you’re at risk for hepatitis C. Symptoms are very mild in the early stages of the disease. You may not have symptoms at all. The U.S. Preventive Services Task Force also recommends hepatitis C screening for adults born between the years 1945 and 1965 (“baby boomers”).