Blood Tests for Liver Function
Liver toxicity is a potential side effect of some arthritis medications. Liver toxicity from arthritis medications is not considered common, but when it occurs it can be potentially serious. Doctors usually order routine blood tests so problems can be detected before they become clinically significant.
Liver enzymes are normally found within the cells of the liver. If the liver is injured or damaged, the liver enzymes spill into the blood, causing elevated liver enzyme levels. Laboratory tests performed on blood samples can detect elevated liver enzymes.
Other blood tests can also signal liver function problems by detecting abnormalities involving plasma proteins and blood clotting factors. Normal or reference values for liver blood tests can vary among laboratories due to the age or gender of the patient, as well as the laboratory method used for testing.
AST or SGOT (aspartate aminotransferase or serum glutamic oxaloacetic transaminase)
AST (SGOT) is not only found in the liver. It is also normally found in heart, muscle, brain, and kidney tissue. Injury to any of these tissues can cause an elevated blood level.
AST (SGOT) normal range is 10-34 IU/L.
ALT or SGPT (alanine aminotransferase or serum glutamic pyruvic transaminase)
ALT (SGPT) is primarily found in the liver, making it a more specific test for detecting liver abnormalities.
ALT (SGPT) normal range is 5-35 IU/L.
Alkaline Phosphatase (ALP)
Alkaline phosphatase (ALP) is an enzyme in the cells which line the biliary ducts of the liver. ALP is also found in other organs including bone, placenta, and intestine. When ALP is elevated, another test known as GGT (gamma-glutamyl transferase) can be ordered by the doctor to confirm that the elevated ALP is being derived from the liver or biliary tract.
ALP normal range is 20-140 IU/L (international units per liter).
Gamma-glutamyl transpeptidase (GGTP) or transferase (GGT)
Gamma-glutamyl transferase (GGT) is an enzyme which is useful clinically when compared to ALP. By comparing the two, it can be determined if the patient has bone or liver disease.
GGT or GGTP normal range is 0-51 IU/L.
Normal GGT + Elevated ALP is suggestive of bone disease
Elevated GGT + Elevated ALP is suggestive of liver or bile-duct disease
Other Liver Function Tests
Bilirubin is produced from the breakdown of hemoglobin (the oxygen- carrying protein pigment) in red blood cells. The liver clears bilirubin from the body by excreting it through bile into the intestine. Elevated bilirubin levels can be indicative of liver disorders or blockage of bile ducts.
In laboratory tests, bilirubin is measured as total bilirubin and direct bilirubin. Total bilirubin, as it's name suggests, is a measurement of all of the bilirubin in the blood. Direct bilirubin is a measurement of a form of bilirubin made in the liver.
Normal range for Direct Bilirubin is 0-0.3 mg/dl and the normal range for Total Bilirubin is 0.3-1.9 mg/dl
Albumin is the main protein in human blood (the primary component of total protein). Albumin is made by the liver. Laboratory testing indicates how well the liver is making albumin. Liver disease results in decreased albumin production.
Albumin normal range is 3.4-5.4 g/dL.
The majority of plasma proteins (albumin and globulins) in the body are produced by the liver. Laboratory testing for total protein is a way to differentiate between normal and abnormal liver function.
Total Protein normal range is 6.0-8.3 gm/dl (grams per deciliter).
The prothrombin time (PT) or protime is a laboratory test used to evaluate normal or abnormal blood clotting. Blood clotting factors are proteins which are made by the liver. If the liver is injured or damaged, the clotting factors are not produced normally.
Prothrombin time normal range is 11 to 13.5 seconds.
Getting stuck with a needle to obtain a blood sample for testing is an unpleasant experience for some patients, while others think it's no problem. Blood testing is necessary so that the doctor has all pertinent information and can then weigh treatment options. Should the patient stay on or stop the medication they are currently taking? What new medication should be added to the patient's regimen?
If a patient has elevated liver enzymes and they stop the medication which is suspected of causing the problem, the enzymes levels usually return to normal within weeks or months.