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 Evaluation of the Patient With a Liver Disorder History and physical examination often suggest a cause of potential liver disorders and narrow the scope of testing for hepatic and biliary disorders. Various symptoms may develop, but few are... read more 
and Laboratory Tests of the Liver and Gallbladder Laboratory Tests of the Liver and Gallbladder Laboratory tests are generally effective for the following: Detecting hepatic dysfunction Assessing the severity of liver injury Monitoring the course of liver diseases and the response to treatment... read more .)
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:
Fatty liver Nonalcoholic Fatty Liver Disease (NAFLD) Fatty liver is excessive accumulation of lipid in hepatocytes. Nonalcoholic fatty liver disease (NAFLD) includes simple fatty infiltration (a benign condition called fatty liver), whereas nonalcoholic... read more should be considered in patients with metabolic syndrome Metabolic Syndrome Metabolic syndrome is characterized by a large waist circumference (due to excess abdominal fat), hypertension, abnormal fasting plasma glucose or insulin resistance, and dyslipidemia. Causes... read more ; it can often be recognized clinically.
Most patients, especially young or middle-aged women, should be screened for autoimmune disorders.
Patients at risk should be screened for malaria Diagnosis Malaria is infection with Plasmodium species. Symptoms and signs include fever (which may be periodic), chills, rigors, sweating, diarrhea, abdominal pain, respiratory distress, confusion... read more
and schistosomiasis Diagnosis Schistosomiasis is infection with blood flukes of the genus Schistosoma, which are acquired transcutaneously by swimming or wading in contaminated freshwater. The organisms infect the... read more 
.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 Alpha-1 Antitrypsin Deficiency Alpha-1 antitrypsin deficiency is congenital lack of a primary lung antiprotease, alpha-1 antitrypsin, which leads to increased protease-mediated tissue destruction and emphysema in adults.... read more .
All patients should have a thorough review of all prescription drugs, herbals, supplements, energy drinks, and recent antibiotics to exclude drug-induced liver injury Liver Injury Caused by Drugs Many medications (eg, statins) commonly cause asymptomatic elevation of hepatic enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase). However, clinically... read more .
All patients should be asked about history of alcohol use.
Abdominal ultrasound with Doppler can evaluate for fatty liver Nonalcoholic Fatty Liver Disease (NAFLD) Fatty liver is excessive accumulation of lipid in hepatocytes. Nonalcoholic fatty liver disease (NAFLD) includes simple fatty infiltration (a benign condition called fatty liver), whereas nonalcoholic... read more , cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic fibrosis that has resulted in widespread distortion of normal hepatic architecture. Cirrhosis is characterized by regenerative nodules surrounded by dense... read more , biliary issues Overview of Biliary Function The liver produces about 500 to 600 mL of bile each day. Bile is isosmotic with plasma and consists primarily of water and electrolytes but also organic compounds: bile salts, phospholipids... read more , and portal and hepatic vein thrombus Portal Vein Thrombosis Portal vein thrombosis causes portal hypertension and consequent gastrointestinal bleeding from varices, usually in the lower esophagus or stomach. Diagnosis is based on ultrasonography. Treatment... read more .
If the entire evaluation reveals no cause, liver biopsy Liver Biopsy Liver biopsy provides histologic information about liver structure and evidence of liver injury (type and degree, any fibrosis); this information can be essential not only to diagnosis but also... read more 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 Imaging Tests of the Liver and Gallbladder Imaging is essential for accurately diagnosing biliary tract disorders and is important for detecting focal liver lesions (eg, abscess, tumor). It is limited in detecting and diagnosing diffuse... read more 
, 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 Primary Biliary Cholangitis (PBC) Primary biliary cholangitis (PBC; formerly known as primary biliary cirrhosis) is an autoimmune liver disorder characterized by the progressive destruction of intrahepatic bile ducts, leading... read more . Persistent unexplained elevations or suspicion of intrahepatic cholestasis warrants consideration of liver biopsy.
