What Do My Blood Test Results Mean? - Part Three - Complete Metabolic Panel

6 - LFT: Liver Function Tests

The test included in Liver Function Panel are "ALT" (Alanine Transaminase sometimes called SGPT), "AST" (Aspartate Aminotransferase sometimes called SGOT), "ALP" (Alkaline phosphatase), "GGT" (Gamma Glutamyl Transpeptidase), "LDH" (Lactic Acid Dehydrogenase), "PT and INR". "Albumin and "Total Bilirubin" are also part of this panel.

So what the heck does all that mean!? The Liver Function Test panel (LFT) is pretty important. It is probably the most ordered panel of tests for diagnosing various disorders and diseases.

• ALT is a liver enzyme found in pancreas, liver, heart, muscles and kidney. The test measures the amount of the enzyme present in the blood. Usually a physician expects to see a low number here because it is normal for this level to be lower than normal range. When you have a higher ALT, it can suggest acute liver damage (for example - due to alcoholism, toxic levels of drugs, illegal drug use, acetaminophen overdose/overuse or viral Hepatitis). But when you have a high cholesterol level coupled with a low ALT, it can suggest a congested liver, Mononucleosis, alcoholism, a kidney infection, liver damage, chemical pollution, or myocardial infarction (past, present, or upcoming). Normal range for malesis 10 - 40 IU/L. Normal range for females is 7- 39 IU/L.

• AST is a liver enzyme found in the liver cells. The test measures the amount of the enzyme present in the blood. AST is normally found in the red blood cells, heart, muscle tissue, liver, pancreas and kidneys. Usually a physician wants to see a low number here because it is normal for this level to be lower than normal range. If the heart or liver is damaged or diseased, AST levels will rise and stay high for up to 4 days after the incident. This test helps identify specific liver disease and is used in the ongoing monitoring of cholesterol medications to make sure they are not damaging the liver. Normal range for males is 14 - 20 U/L. Normal range for females is 10 - 36 U/L.

• ALP is a liver enzyme found in the biliary ducts of the liver. Elevated ALP is present in Hepatitis, gallstones, liver cancer, heart failure, Mononucleosis, pregnancy, bone injuries, rapid bone growth (puberty), and Vitamin D deficiency. This test may be used as a tumor marker. It is a consideration in gall bladder disease and bile duct blockages. A physician may order this test if he sees bone problems on X-rays or when he wants to see how well a treatment for Vitamin D deficiency is working for the patient. Normal range for adults is 25-100 U/L. Normal range for children is 300 U/L or less.

• GGT is a liver enzyme found in the bile ducts. Elevated GGT indicates a bile flow problem and is often present in chronic alcoholism and drug abuse. Other reasons for elevated GGT can be: Congestive Heart Failure, Cirrhosis, toxic use of drugs, Hepatitis, or liver tumor. Elevated GGT always indicates bile flow problems, not bone disease the way ALP test does. Normal range is 0 - 51 IU/L.

LDH is an enzyme found in many body tissues, including the liver.

• Elevated levels of LDH may indicate liver damage. Along with other tests, this test is useful in confirming stroke, Hepatitis, Myocardial Infarction or Pulmonary Infarction. It is also used in the staging of Melanoma and to determine the performance of chemotherapy in regard to Lymphoma. False readings usually happen when the tubes of blood are exposed to extreme fluctuation of temperatures or if the blood is hemolyzed which happens either when the blood was collected or from the patient's use of NSAIDS or antibiotics.

• Low levels may indicate Hypoglycemia, malnutrition, or organ damage. This test is done in conjunction with 5 other LDH tests, so you will often have more than one result. Normal range varies widely from lab to lab, but a general reference is 100 - 300 IU/L.

PT and INR -

• PT is also called Prothrombin time test and evaluates your blood's ability to clot. It helps diagnose bleeding disorders.

• The INR part is the international normalized ratio which means that no matter what lab did your test, your physician will understand the results.

• A PT is almost always done with a PTT test (Partial Prothrombin Time) which monitors anticoagulant drug therapy such as Warfarin (Coumadin), Lovenox, or Heparin - these drugs slow down blood clotting. These tests are always performed before any surgical event. So if you are on anticoagulant drugs, a PT/INR will be routinely performed to make sure your drugs are working properly and that your PT/INR are appropriately prolonged.

• Normal PT Values: 10-12 seconds. A prolonged PT can be due to a vitamin K deficiency, hormones replacement or contraceptive drugs, liver disease, and overuse of the anti-coagulant drugs. The PT result can also be altered by a diet high in vitamin K such as liver meat, green tea, dark green vegetables and soybeans.

• Normal PTT Values: 30 to 45 seconds. Prolonged PTT times can be due to liver problems, Lupus and other diseases that result in poor clotting.

• Normal INR Values: 1 to 2. This is universal and standardized in laboratories in all countries since the 1980s.

Bilirubin monitors and diagnoses red cell destruction, pancreatic diseases, blocked bile ducts, liver disease like Hepatitis, Cirrhosis, and Gall Stones, evaluates for Sickle Cell Anemia, and Jaundice in newborns. Normal range for "direct Bilirubin" is 0 - 0.3 mg/dL. Normal range for "total Bilirubin" (indirect) is 0.3-1.0 mg/dL.

• A false reading leading to a decreased Bilirubin can happen if one has high cholesterol - too much lipids in the blood. If the blood becomes hemolyzed in the collection and/or transport process, or if the blood is exposed to light, it can also lead to a false reading.
• ALWAYS ask for this test to be repeated if you have abnormal results.

Jaundice needs immediate attention.

• Jaundice happens when the white part of the eye and the skin becomes yellow. The disease is present when the Bilirubin reading is 2.5 mg/dL or above.
• Increased or elevated total (indirect) Bilirubin can indicate Mononucleosis, Gilbert's Disease, Hemolytic Anemia, Jaundice (especially in newborns), Hepatitis, Sickle cell anemia, Pernicious Anemia, low exposure to the sun, toxic effects of some drugs or transfusion reaction.
• Decreased total (indirect) Bilirubin levels are seen in people who eat excessive amount of fats and those who eat a diet low in nitrogen-bearing foods.
• Increased direct Bilirubin can indicate Cirrhosis of the liver or Hepatitis.

As with any blood test, what you consume can alter the outcome of the test results.

• Alcohol can affect the PT/INR test.
• Antibiotics can increase the PT/INR.
• Contraceptives and hormone replacement and Vitamin K can decrease PT.
• Foods like beef and pork liver, green tea, broccoli, kale, turnip greens, and many soybean foods have huge amounts of Vitamin K which affects blood clotting.

Your doctor should be kept informed if any of the above reasons could affect your blood test results.

It is best to fast on most blood tests unless the test requires you to have some kind of food in advance. Your doctor or the lab should tell you how to prepare for the test as well as which foods not to eat. Always tell the lab what you ate before the test.

• For example, a cup of coffee will moderately reduce iron absorption in the blood by almost 30 percent. However, a cup of tea will greatly reduce iron absorption in the blood by nearly 75 percent. Orange juice will increase iron absorption by 100% or more. Both non-fasting and fasting are very important.

The order in which the tubes are drawn is important to prevent cross contamination in the tubes. First blood draw is for blood culture (if ordered), then the coagulation tube (purple), then the non-additive tubes, and lastly the additive tubes.

Don't be afraid to question the phlebotomist if you think the order of the draw is incorrect.

• They won't like it, but hey, it is your blood and how many times do you want to be stuck with a needle? I'd rather question and get a dirty look than be stuck again.

Here are general guidelines for fasting of food and beverages including caffeine for 8 to 12 hours before your blood test.

Amylase - Pancreatitis disorder and pancreatic disease. NO fasting.

ANA - (Antinuclear Antibody test) Lupus, Oolymyosistis, autoimmune diseases. NO fasting.

aPTT - (Activated Partial Thromboplastin Time) evaluates risk of excessive bleeding prior to a surgical procedure. NO fasting.

AIC - (Hemoglobin A1C or Glycohemoglobin) Diabetes and Pre-diabetes. NO fasting.

BMP - (Basic Metabolic Panel) Diabetes and kidney disease. You may be asked to fast for 10 to 12 hours prior to test.

CBC - (Complete Blood Count/Hemogram) general health, Anemia or infections, toxic substance exposure. NO fasting.

CMP - (Comprehensive Metabolic Panel) kidneys, liver, electrolyte and acid/base balance, blood sugar and blood proteins and cholesterol. You may be asked to fast for 10 to 12 hours prior to test.

Electrolytes - (Electrolyte Panel) fluids and electrolyte balance. NO fasting.

Glucose - (Fasting Blood Sugar) blood glucose level, diabetes, Pre-diabetes, and Hypoglycemia. Fast 8-12 hours pre-test including avoidance of caffeine.

HIV Antibody - (Human Immunodeficiency Virus) HIV infection. NO fasting.

Lipid Profile - Coronary heart disease, stroke, blood vessel blockage, hardening of arteries. Avoid food and beverages, except water before your test.

Lyme Disease - (Lyme Antibodies Detection) exposure to Lyme disease. NO fasting.

Mono - (Mononucleosis) NO fasting.

It is best to avoid all beverages with caffeine including decaffeinated coffee. While most caramel colored sodas contain caffeine, root beer soda has no caffeine.

I hope this series of three articles has given you some understanding of your blood tests, the results, why they are done, and most importantly - to remind you that you are entitled to copies of your records when you ask for them. They will not automatically be given to you.

Published January 2012

If you missed Part 1 and Part 2 because you clicked a different link to get to this article, here are the links:

Link to What Do My Blood Test Results Mean? - Part One - Complete Metabolic Panel -CMP

Link to What Do My Blood Test Results Mean? - Part Two - Complete Metabolic Panel - CMP

Thank you for reading. Your comments are welcomed.