What Is a Blood Test? A blood test is when a sample of blood is taken from the body to be tested in a lab. Doctors order blood tests to check things such as the levels of glucose, hemoglobin, or white blood cells. This can help them detect problems like a disease or medical condition. Sometimes, blood tests can help them see how well an organ (such as the liver or kidneys) is working. What Is a Hepatic (Liver) Function Panel? A liver function panel is a blood test that helps doctors check for liver injury, infection, or disease. Liver function panels also can check for side effects in the liver from some medicines. Why Are Liver Function Panels Done? A liver function panel is done to learn information about the levels of: Albumin and total protein, which help build and maintain muscles, bones, blood, and organ tissue. Low levels may be seen with liver or kidney disease, or nutritional problems. Liver enzymes: Alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). These enzymes help the liver convert food into energy. When their levels are high, it can be a sign of that the liver is injured or irritated. Bilirubin. Bilirubin is made when red blood cells break down. The liver changes the bilirubin so that it can be excreted from the body. High bilirubin levels may mean there is a problem with the liver. This can make skin look yellow, a condition called jaundice. How Should We Prepare for a Liver Function Panel? Your child may be asked to stop eating and drinking for 8 to 12 hours before the test. Tell your doctor about any medicines your child takes because some drugs might affect the test results. Wearing a T-shirt or short-sleeved shirt for the test can make things easier for your child, and you also can bring along a toy or book as a distraction. How Is a Liver Function Panel Done? Most blood tests take a small amount of blood from a vein. To do that, a health professional will: clean the skin put an elastic band (tourniquet) above the area to get the veins to swell with blood insert a needle into a vein (usually in the arm inside of the elbow or on the back of the hand) pull the blood sample into a vial or syringe take off the elastic band and remove the needle from the vein In babies, blood draws are sometimes done as a "heel stick collection." After cleaning the area, the health professional will prick your baby's heel with a tiny needle (or lancet) to collect a small sample of blood. Collecting a sample of blood is only temporarily uncomfortable and can feel like a quick pinprick. Can I Stay With My Child During a Liver Function Panel? Parents usually can stay with their child during a blood test. Encourage your child to relax and stay still because tensing muscles can make it harder to draw blood. Your child might want to look away when the needle is inserted and the blood is collected. Encourage your child to relax by taking slow deep breaths or singing a favorite song. How Long Does a Liver Function Panel Take? Most blood tests take just a few minutes. Occasionally, it can be hard to find a vein so the health professional may need to try more than once. What Happens After a Liver Function Panel? The health professional will remove the elastic band and the needle and cover the area with cotton or a bandage to stop the bleeding. Afterward, there may be some mild bruising, which should go away in a few days. When Are Liver Function Panel Results Ready? Blood samples are processed by a machine, and it may take a few hours to a day for the results to be available. If the test results show signs of a problem, the doctor might order other tests to figure out what the problem is and how to treat it. Are There Any Risks From Liver Function Panels? A liver function panel is a safe procedure with minimal risks. Some kids might feel faint or lightheaded from the test. A few kids and teens have a strong fear of needles. If your child is anxious, talk with the doctor before the test about ways to make the procedure easier. A small bruise or mild soreness around the blood test site is common and can last for a few days. Get medical care for your child if the discomfort gets worse or lasts longer. If you have questions about the test, speak with your doctor or the health professional doing the blood draw. Back to Articles Related Articles Blood Test: Bilirubin Doctors may order bilirubin blood tests for infants or older kids if they see signs of the skin taking on the yellow discoloration known as jaundice. Read More Hepatitis Hepatitis is an inflammation of the liver. Most cases are caused by a virus — either hepatitis A, hepatitis B, or hepatitis C — all of which can be passed to others by someone who is infected. Read More Mononucleosis (Mono) Mononucleosis - or "mono" - is an infection that causes flu-like symptoms. It usually goes away on its own in a few weeks with the help of plenty of fluids and rest. Read More Blood Test: Aspartate Aminotransferase (AST, or SGOT) An aspartate aminotransferase (AST) blood test is often part of an initial screening for liver problems. Read More Blood Test: Alanine Aminotransferase (ALT, or SGPT) An alanine aminotransferase (ALT) blood test is often part of an initial screening for liver disease. Read More Jaundice in Newborns Jaundice is when a baby has yellowing of the skin and whites of the eyes. Most types of jaundice go away on their own. Read More Getting a Blood Test (Video) A blood test might sound scary, but it usually takes less than a minute. Watch what happens in this video for kids. Read More Hepatitis B Hepatitis B can move from one person to another through blood and other body fluids. For this reason, people usually get it through unprotected sex or by sharing needles. Read More What's Mono? Kissing is just one of the ways that someone can spread mononucleosis. Most people who get mono are teens or young adults, but kids can get it too. Read More Hepatitis Hepatitis, an infectious liver disease, is more contagious than HIV. Find out about the different types of hepatitis. Read More Hepatitis It's sneaky, it's silent, and it can permanently harm your liver. Read this article for more information on hepatitis. Read More Blood Test (Video) These videos show what's involved in getting a blood test and what it's like to be the person taking the blood sample. Read More Blood Test: Liver Function Tests If your liver isn't working properly, it can affect your overall health. Find out why doctors do liver function tests and what's involved for teens. Read More Your Liver Your liver cleans your blood and plays an important part in digestion. Find out more in this article for kids. Read More Mononucleosis (Mono) It's sometimes called "the kissing disease," but kissing is just one of the ways that someone can catch mono. Read More Liver Tumors Tumors happen when cells form a mass or growth. Liver tumors can be benign (not cancerous) or malignant (cancerous). Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.