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Is My Liver Under Distress?
Using Liver Function Tests (LFTs) to Help With Screening
Kara Rogers
Physician Reviewed
Nov 10, 2025
Understanding Liver Function Tests at Your Annual Physical
At an annual physical, your healthcare provider will order tests that provide information regarding your overall metabolic health. One of the lab panels, the Comprehensive Metabolic Panel (CMP), can provide clues to help determine if your liver is under distress.
The CMP lab panel includes liver function tests (LFTs), which measure levels for:
Aspartate transaminase (AST)
Alanine transferase (ALT)
Alkaline Phosphatase (ALP)
Albumin
Total bilirubin
Before explaining these tests in further detail, it is important to have a solid understanding of the role that protein and enzymes play within the human body.
The Role of Proteins and Enzymes
Proteins are required for nearly all bodily functions. Enzymes are proteins that bind to molecules and help to speed up numerous chemical reactions that occur in the body. Enzymes can break down or build up other substances within the body.
AST, ALT, and ALP are all enzymes that are tested within the CMP. Let’s review how the LFT testing within the CMP lab panel provides valuable insight to your healthcare provider regarding the health of your liver.
Aspartate transaminase (AST)
Aspartate transaminase, or AST, is an enzyme that is located primarily in the liver, heart, and skeletal muscles within the body. This enzyme is not considered to be liver specific; however, if the AST is elevated there could be an indication that the liver is struggling to function properly.
There are many reasons why the AST can be elevated. Some of the major factors that cause an increase in AST include:
Congestive heart failure
Alcohol
Statin use
Muscle injury
Muscular Dystrophy
Strenuous exercise
Rhabdomyolysis (life-threatening muscle breakdown)
Excessive acetaminophen use
Most people are aware that alcohol can cause liver disease; however, many people do not know that an AST elevation can also represent a diagnosis of Metabolic-dysfunction Associated Steatotic Liver Disease (MASLD).
The acronym MASLD is used as the new nomenclature. This is a medical diagnosis where there is extra visceral fat stored within the liver. This disease process is caused by a metabolic process and is not caused by alcohol. It was previously referred to as Non-Alcoholic Fatty Liver Disease (NAFLD).
An AST increase can also indicate Metabolic-dysfunction Associated Steatohepatitis (MASH). This medical diagnosis represents a combination of visceral fat in the liver and also a significant amount of scarring, inflammation, and stiffness known as fibrosis. This disease process was formerly known as Non-Alcoholic Steatohepatitis (NASH). This is also not caused by alcohol, but instead by a metabolic pathway.
Alanine Transferase (ALT)
Alanine transferase, or ALT, is another function test within the CMP lab panel. This enzyme is predominantly found within the liver and is extremely sensitive in detecting liver distress and damage.
An elevated ALT level would prompt further testing. More specifically, an elevated ALT level could indicate viral Hepatitis A, B, or C, and would need to be evaluated further.
Other reasons why ALT can be increased outside of the normal levels are highly suggestive of MASLD and MASH as discussed above. Additional possibilities could be drug-induced hepatitis and mononucleosis (mono).
Alkaline Phosphatase (ALP)
Alkaline Phosphatase (ALP) is another enzyme that is also found in the liver. When this is elevated, it is usually not due to direct liver cell damage because the majority of ALP is found in the bile canaliculi.
The bile canaliculi are small tubes that carry bile into larger bile ducts within the liver. The bile eventually empties into the common hepatic duct. From there, bile can either go into the gallbladder for storage or move into the common bile duct which excretes into the small intestine to help with digestion and emulsification of fat.
When ALP is elevated, this can indicate that the bile ducts are blocked (usually by a gall stone) and build pressure up. The ALP can seep out of the liver cells and bile ducts into the blood stream resulting in an ALP elevation.
Cholestasis is the medical term used when bile flow is impeded. ALP also resides in the intestines and kidneys, but higher concentrations are found in the liver and bone.
Increased ALP can also be a sign of liver cancer (hepatocellular carcinoma), hepatitis, cirrhosis, and drug-induced liver damage.
Additionally, ALP is also found in the bones. It is produced by osteoblasts, which are bone-forming cells. ALP is required for bone mineralization and growth.
An elevation in ALP can point to bone disorders like osteomalacia (softening of the bones) and Paget’s Disease, which is a chronic bone disorder where the bone is broken down and remodeled too quickly.
An abnormal bone structure can be the result of Paget’s Disease. ALP elevations can also represent bone metastases (cancer that has moved to the bones), osteogenic sarcoma (a bone cancer type), multiple myeloma (a blood cancer type), as well as the normal process in which a fracture or broken bone would heal.
It can also suggest hyperparathyroidism, which involves overactive parathyroid glands. This leads to an abundance of calcium in the blood and creates increased bone turnover.
Albumin
Albumin is another component of the CMP. The role of proteins in the body is so important, and albumin is one such protein produced by the liver.
Hypoalbuminemia is when there is a low albumin level. When the liver has sustained damage, its ability to produce this important protein becomes difficult. Therefore, hypoalbuminemia can indicate liver disease.
Total Bilirubin
The CMP lab panel also incorporates a Total Bilirubin test. This test measures the amount of bilirubin in your blood.
Red blood cells are within the body and move iron and oxygen throughout the body. Bilirubin is created when red blood cells break down. Elevated Total Bilirubin levels can indicate that the liver is under distress.
It can also suggest the presence of hepatitis or cirrhosis, gallbladder problems, or increased breakdown of red blood cells. A healthy liver normally processes and removes bilirubin as waste from the blood easily.
Please note that there is a genetic disorder called Gilbert’s Syndrome, where people will have higher than normal total bilirubin levels; however, this is a benign process and does not cause liver damage. Gilbert's Syndrome is an inherited condition that affects the liver's ability to process bilirubin.
Final Thoughts: When to Seek Liver Screening
In conclusion, if any of these tests are abnormal within the CMP, it will certainly prompt your healthcare provider to order additional testing as there is a possibility of liver disease.
It is important to note that if you have Diabetes Type II, high cholesterol, elevated blood pressure, obstructive sleep apnea, hypothyroidism, hyperthyroidism, coronary artery disease, or are overweight, there can still be a possibility of having conditions such as Metabolic-dysfunction Associated Steatotic Liver Disease (MASLD) and Metabolic-dysfunction Associated Steatohepatitis (MASH).
Having the risk factors and diseases mentioned above can put a person on a metabolic pathway to liver destruction.
The LFTs do not always have to be elevated for a person to have MASLD or MASH. Sometimes liver enzymes are not elevated until the later stages of the disease process. There are rarely physical symptoms until the later stages have become established.
Schedule a Screening
We would be honored to screen you for MASLD and MASH at Covenant Metabolic Specialists if you have several of the risk factors mentioned above.
Call us today, and we would be happy to sit down with you and provide education about your liver health.
