Because aminotransferases and alkaline phosphatase are included in commonly done laboratory test panels, abnormalities are often detected in patients without symptoms or signs of liver disease. In such patients, the physician should obtain a history of exposure to possible liver toxins, including alcohol, prescription and nonprescription drugs, herbal teas and botanical remedies, and occupational or other chemical exposures.
(See also Evaluation of the Patient With a Liver Disorder and Laboratory Tests of the Liver and Gallbladder.)
Aminotransferases
Mild isolated elevations of alanine aminotransferase (ALT) or aspartate aminotransferase (AST; < 2 times normal) may require only repeat testing; they resolve in about one third of cases. It is important to clarify if laboratory tests were done in the fasting state because oral intake can cause mild elevations in tests of liver function. If abnormalities are present in other laboratory tests, are severe, or persist on subsequent testing, further evaluation is indicated as follows:
Steatotic liver disease should be considered in patients with metabolic syndrome; it can often be recognized clinically.
Patients should be screened for hepatitis B and C.
Patients > 40 should be screened for hemochromatosis.
Patients < 30 should be screened for Wilson disease.
Most patients, especially young or middle-aged women, should be screened for autoimmune disorders.
Patients at risk should be screened for malaria and schistosomiasis.
Most patients, especially those with early-onset obstructive lung disease, especially in the absence of smoking history, should be screened for alpha-1 antitrypsin deficiency.
Most patients should be screened for celiac disease.
All patients should have a thorough review of all prescription drugs, herbals, supplements, energy drinks, and recent antibiotics to exclude drug-induced liver injury.
All patients should be asked about history of alcohol use.
Abdominal ultrasound with Doppler can evaluate for steatotic liver disease, cirrhosis, biliary issues, and portal and hepatic vein thrombus.
If the entire evaluation reveals no cause, liver biopsy may be warranted.
Alkaline phosphatase
Isolated elevation of alkaline phosphatase levels in an asymptomatic patient requires confirmation of hepatic origin by showing elevation of 5´-nucleotidase or gamma-glutamyl transpeptidase. If hepatic origin is confirmed, liver imaging, usually with ultrasonography or magnetic resonance cholangiopancreatography, is indicated.
If no structural abnormality is found on imaging, intrahepatic cholestasis is possible and may be suggested by a history of exposure to drugs or toxins. Infiltrative diseases and liver metastases (eg, due to colon cancer) should also be considered. In women, antimitochondrial antibody should be obtained to check for primary biliary cholangitis. Persistent unexplained elevations or suspicion of intrahepatic cholestasis warrants consideration of liver biopsy.
