Blood Tests Specific to the Liver

“So Morgan, last time we were talking about getting blood drawn and the Complete Blood Count test. Once I’ve had this, why would I have to have another blood test?”

“If your CBC comes back with abnormal values Plucky, your doctor will need to know more. You see, the CBC gives you an overview of your health. More specific tests are needed to narrow down where your problem might lie.”

LIVER FUNCTION TESTS

Liver Enzyme Tests, formerly called Liver Function Tests, measure various chemicals in your blood made by your liver. Various liver disorders alter the blood level of these chemicals. These tests are not diagnostic of a specific condition; they indicate that there may be a problem with your liver function.

ENZYME TESTS

Liver enzyme tests measure current liver cell injury by the amount of enzymes that are leaked out of damaged or dying liver cells. 

• Alanine aminotransferase (ALT). This is an enzyme that helps process proteins. It is found mainly in your liver cells and to a lesser degree in your kidneys, heart, muscles and pancreas. ALT is measured to see if the liver is damaged or diseased. Low levels are normally found in your blood. When you have a liver disorder, the liver cells spill this enzyme into your blood, raising the level.
• Aspartate aminotransferase (AST). This enzyme plays a role in your metabolism-the process that converts food to energy. AST is also found mainly in your liver cells and when your liver is damaged the same process happens as with your ALT. However, AST can also be released if heart or skeletal muscle is damaged. For this reason, ALT is usually considered to be more specifically related to liver problems.
• Alkaline Phosphatase (ALP). This is also an enzyme found mainly in the liver. It can also be found in your bones, intestines, kidneys and other organs. The liver makes more ALP than the other organs or the bones. Some conditions cause large amounts of ALP in your blood. These can include rapid bone growth, bone disease, hyperparathyroidism (a disease that affects how much calcium is in your bones), vitamin D deficiency or damaged liver cells.
• Lactate dehydrogenase (LD or LDH). This is an enzyme found in almost all of your body’s cells (as well as in bacteria) and is released from cells into the fluid part of your blood (plasma) when the cells are damaged or destroyed. Thus, the blood level of LDH is a general indicator of tissue or cellular damage.
• Gamma-glutamyl transferase (GGT). High levels of this enzyme are found in the cell membranes in tissues in the liver, bile duct and the kidneys. Bloodstream GGT levels will be higher in people with diseases of the liver and bile ducts. This test can be used to determine the cause of elevated ALP. Both ALP and GGT are elevated in disease of the bile duct and in some liver diseases, but only ALP will be elevated in bone disease. Increased GGT level indicates that a person’s liver is being damaged but does not specifically point to a condition that may be causing the injury. GGT can be used to screen for chronic alcohol abuse (it will be elevated in about 75% of chronic drinkers). 
• 5 “N” Tase (5’NT). Higher levels of this enzyme will indicate a problem with bile secretion. Hepatitis C or cirrhosis can cause blockage of bile flow.

PROTEIN TESTS

Liver function tests look at levels of proteins made by the liver.

• Bilirubin (BIL). When red blood cells complete their lifecycle and breakdown naturally, they produce bilirubin. It’s a yellow pigment that’s passed on to the liver and excreted in your bile. Most of the time, the body produces as many red blood cells as it breaks down. However, if the red blood cells break down more rapidly or if liver function becomes impaired, bilirubin levels in the blood rise. In patients with Hepatitis, bilirubin levels tend to fluctuate. A prolonged persistent rise in bilirubin for a patient with chronic Hepatitis C usually indicated severe liver dysfunction. When your bilirubin is high the whites of your eyes and your skin will be a yellowish color (jaundice). This is one of the three tests used to determine your wait time for a liver transplant. There are two measurements for your bilirubin.

1. Total bilirubin (unconjugated). This measures the levels of all the bilirubin in your blood.
2. Direct bilirubin (conjugated). Measures the bilirubin that has been processed by the liver and attached to other chemicals.

• Albumin (ALB). As we’ve talked about, is the major blood protein made by the liver. One function is to keep the blood from leaking through your blood vessels, which can cause fluid retention in the ankles (edema), lungs or abdomen (ascites). Low levels of albumin may be due to liver injury or kidney disease, malnutrition or even a low protein diet.
• Prothrombin time (PT). This measures how quickly your blood clots, which is dependent on clotting factors (proteins) that are made by the liver. PT is used as a marker of advanced liver disease and can indicate blood clotting problems where it takes you longer to stop bleeding. Your lab may also give PT results that have been converted to an internationally recognized and easily comparable value that’s called the International Normalized Ratio (INR). The INR is one of the three factors used to determine wait time for a liver transplant.
• Alpha-fetoprotein (AFP). This test is used as a marker for potential liver cancer. Not everyone with liver cancer has this marker. Pregnant women usually have higher levels of this protein which is also used to look for problems in pregnancy. You may have higher levels of this protein if you have hepatitis or cirrhosis.
• Total Protein (T/P). This test measures the two main proteins in your blood: albumin and globulin. This test will give your A/G ratio. Normally there is a little more albumin than globulins, giving a normal A/G ratio of slightly over 1. Because disease affects the relative amount of albumin and globulins, the A/G ratio can provide a clue as to the cause of the change in protein levels. A low A/G ratio may reflect over production of globulins, such as seen in autoimmune diseases, or an underproduction of albumin such as may occur with cirrhosis, or it could be selective loss of albumin from the circulation, as may occur with kidney disease. A high A/G ratio suggests underproduction of immunoglobins as can be seen in some genetic deficiencies and in some types of leukemia.

“Oh my, look at the time! I’m sorry Morgan but I have to go. This is really great information you’re sharing with me but I have a photo shoot to do. As you know, Sunburst Oranges was the recent recipient of the American Liver Foundation Greater Los Angeles division’s first annual “Liver Lover” award and I am accepting of their behalf.”

“That is so great Plucky! I have seen you and Sunburst Oranges at some of the Liver Life Walks working really hard to spread awareness about liver disease and sharing those delicious Plucky brand oranges. I’ll finish this up and you can read it later. Just a couple of things before you go. Would you bring me back some of those oranges? And, can I have your autograph?”

"Very funny Morgan!"

“O.K., where were we? Yes, we just finished with the blood tests specific to the liver. I’m including one more because it is the third test used to determine your wait time for a liver transplant.”

OTHER TESTING

• Creatinine, is a breakdown product of creatine, which is made by the liver and transported to your muscles. Your kidneys excrete the waste product creatinine and, when your kidneys are damaged, creatinine levels rise. When your liver stops functioning in end-stage liver disease, this can cause serious kidney problems as well.

Lab tests, or bloodwork, can give important clues about your overall health and the health of your liver. I strongly suggest keeping a copy of all lab results. This will give you your “baseline” and allow you to watch for changes in your health over time. This will also help you, and your doctor, to check the impact of any treatments you undergo.

Again, factors such as age, gender, stress, meds, infections and a host of other things can all affect your test results. So, keep all these factors in mind when reviewing your lab results. Understanding your test results may seem confusing at first. But, they can help you take charge of your health and understand why your doctor prescribes certain tests and medications.

With practice, over time, it will all become easier to understand. "I've got to go see what our new 'rock star' plucky is doing at this photo shoot so, until next time, LOVE YOUR LIVER!"

Morgan d' Organ