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The prevalence of abnormal liver test results in the general population is estimated to be between 10% and 20%. The terms liver tests or liver chemistries are recommended to describe more accurately the tests used to assess liver health, instead of the term liver function tests. Defining normal ranges for liver transaminase levels can be challenging. Levels are affected by factors such as body mass index and sex. Elevated transaminase levels are associated with increased risks of liver-related and all-cause mortality. Patient with signs or symptoms of liver disease or abnormal liver test results should be evaluated to determine the etiology. For patients with abnormal liver test results, the initial evaluation should include a review of previous laboratory test results, medical and family histories, substance use, and drugs, including over-the-counter drugs and herbal supplements. Physical examination results often are normal but findings may be consistent with acute disease. Tests should include a complete blood cell count; alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, and albumin levels; prothrombin time; hepatitis B surface antigen; hepatitis B core antibody; hepatitis C antibody; ferritin and iron levels and transferrin saturation; and right upper quadrant abdominal ultrasonography. Additional tests and imaging should be based on patient-specific risk factors and the pattern of abnormal liver test results.

Case 1. HF is a 47-year-old woman with a history of autoimmune thyroiditis and hypothyroidism for which she takes levothyroxine. She comes to your office today with onychomycosis. Before initiating oral antifungal therapy, you obtain baseline liver tests. The results show an elevated alkaline phosphatase (AP) level of 215 U/L; the other results are normal.

The prevalence of abnormal liver test results in the general population is estimated to be between 10% and 20%.1 Asymptomatic patients may present with conditions that warrant screening for liver disease, such as risk factors for nonalcoholic fatty liver disease (eg, metabolic syndrome, diabetes, obesity, dyslipidemia, hypertension), and conditions associated with chronic liver disease (eg, autoimmune disease, alcohol use disorder, hemochromatosis).2 Other patients may require screening because of signs or symptoms of liver disease (Table 1), use of hepatotoxic drugs, a family history of liver disease, viral hepatitis identified on screening tests, or nonspecific symptoms (eg, nausea, fatigue, anorexia).

Body Part/SystemExamination Finding
Central nervous systemDrowsiness, confusion
Asterixis (tremor of the hand with wrist extension)
HeadJaundice (may see yellowing of mucous membranes beneath the tongue)
Scleral icterus
Fetor hepaticus (sweet, musty breath odor due to increased concentrations of dimethyl sulfide)
Parotid enlargement
Spider nevi
ChestGynecomastia
Thinning of axillary hair
Spider angioma
AbdomenAscites
Contracted or enlarged liver
Splenomegaly
Caput medusae (engorged superficial epigastric veins radiating from the umbilicus)
Hemorrhoids
Hands and nailsPalmar erythema (most notable over thenar and hypothenar eminences)
Clubbing
Terry nails (whiteness of proximal half of nail plate)
Dupuytren contracture (fibrosis of palmar fascia resulting in limited finger extension)
Genitourinary (male)Testicular atrophy
Lower extremitiesEdema
Petechiae
Distal erythema

Common Liver Tests

The terms liver tests or liver chemistries are recommended to describe more accurately the tests used to assess liver health, instead of the term liver function tests.2 For example, liver enzyme levels do not measure liver function, but are indicators of hepatocellular damage or biliary obstruction. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), and alkaline phosphatase (AP) are liver enzymes. Markers of hepatocellular synthetic function include albumin and prothrombin time (PT). Bilirubin is a marker for both hepatocellular damage and synthetic function.

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