Testing for Hepatitis C: How Hepatitis C Antibody Works
Why Test for Hepatitis C?
The liver serves many important functions. It filters toxins out of the blood, processes sugar and iron, and produces bile to help digest food.
The hepatitis C virus attacks the human liver. It causes damage and, over time, destroys it by killing off healthy cells. The virus leaves tough scar tissue behind and 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, and the sooner it can be cured.
The Hepatitis C Antibody Test
The first test doctors usually order is the hepatitis C antibody test.
When harmful foreign agents like bacteria, fungi, parasites and viruses enter the human body, the body’s immune system makes special proteins. These are called antibodies. The human body makes millions of different antibodies, each tailored to fight millions of different invaders.
The antibodies try to neutralize or destroy the foreign invader before it can do harm. The hepatitis C antibody test looks for hepatitis C antibodies in the bloodstream. If they’re present, so is the virus. However, it doesn’t prove there’s an active, current infection.
How Do Antibodies Fight Harmful Invaders?
Hepatitis C antibodies are made by blood plasma cells to attack only the hepatitis C virus. They bind to it and set it up for attack by other parts of the immune system.
According to the Centers for Disease Control and Prevention (CDC), up to a quarter of the people who are infected by the hepatitis C virus clear it from their bodies without treatment. Others will develop liver scarring that will progress to cirrhosis (a state where the liver is so scarred it can barely function), liver failure, or liver cancer over time.
The Hepatitis C RNA Test
Although the hepatitis C antibody test shows that the patient has been exposed to hepatitis C, it can’t show whether the infection is active. Instead, doctors look for particles from the nucleus of the virus cells, the ribonucleic acid (RNA). If the hepatitis C RNA qualitative test finds viral RNA, it means there’s an active hepatitis C infection.
A second RNA test then measures the number of viral RNA particles in the blood before and during treatment. Called the hepatitis C RNA quantitative test, it shows how well the treatment is working.
The Hepatitis C 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. About 75 percent of people who have hepatitis C have genotype 1. Twenty to 25 percent have genotypes 2 or 3, and a few others have genotypes 4, 5, and 6, according to the U.S. Dept. of Veterans Affairs.
Tailoring the Treatment to Different Genotypes
Different hepatitis C genotypes are genetically distinct groups of the virus. They all respond differently to treatment. Doctors tailor the treatment to match the patient’s hepatitis C genotype. This helps to predict how long the treatment should last and what the outcome should be.
People who have genotype 1 must be treated twice as long (48 weeks) as people who have genotypes 2 and 3 (24 weeks).
When to Be Tested for Hepatitis C
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
- are a health care worker who’s had a needlestick injury
- have tattoos or body piercings done in non-regulated settings
- have had a sexual partner with hepatitis C, now or in the past (getting hepatitis C this way is rare)
- were born to a mother who has hepatitis C
If you’re at risk for hepatitis C, get tested. Symptoms are very mild in the early stages of the disease, and you may not have symptoms at all. The U.S. Preventive Services Task Force recommends hepatitis C screening not only for people at high risk of infection, but also for adults born between the years 1945 and 1965 (“baby boomers.”)
How Hepatitis C Can’t Be Passed Along
Hepatitis C is contagious, but it can only be passed to another person by blood contact through a break in the skin. The virus must pass directly into the other person’s bloodstream.
You can’t get Hepatitis C from the following:
- sharing eating utensils
- hugging, kissing, or holding hands
- coughing or sneezing
- through food or water
- Hepatitis C Genotypes and Quasispecies (2013, January 10). National Hepatitis C Program Office. Hepatitis C Technical Advisory Group 2005. U.S. Department of Veterans Affairs. Retrieved November 13, 2013 from http://www.hepatitis.va.gov/provider/reviews/genotypes.asp
- Hepatitis C Overview (2012, October 22). Hepatitis C FAQs for the Public. Centers for Disease Control and Prevention. Retrieved November 13, 2013 from http://www.cdc.gov/hepatitis/C/cFAQ.htm#overview
- Hepatitis C Testing (2013, July 9). Lab Tests Online. American Association for Clinical Chemistry. Retrieved November 13, 2013 from http://labtestsonline.org/understanding/analytes/hepatitis-c/tab/test
- Screening for Hepatitis C Virus Infection in Adults. (2013, June). U.S. Preventive Services Task Force. Retrieved November 18, 2013, from http://www.uspreventiveservicestaskforce.org/uspstf/uspshepc.htm