Case Presentation and EvolutionA 25-year-old female retail manager, who had been gen-erally healthy, presented with complaints of mild fatigue.She denied fever, myalgia, jaundice, night sweats, orweight loss. She exercised regularly by running 2–3 milesper day and doing light weight lifting several times perweek, but did not engage in an excessive exercise regimen.She denied muscle pain or weakness. She had no previousmedical history, and her family history was only significantfor paternal dyslipidemia and an older brother with thyroidcancer. She occasionally took aspirin and/or ibuprofen forheadache or muscle cramping, and only drank a coupleglasses of wine per week. Physical examination wasessentially normal.Initial laboratory studies were significant for isolatedaspartate aminotransferase (AST) elevation of 283 U/L,with all other liver chemistry normal, including an alanineaminotransferase (ALT) level of 13 U/L. Complete bloodcount, including reticulocytes, was normal. Work-up forthe presence of chronic liver disease, including viral(hepatitis B and C serology, and Epstein–Barr virus andcytomegalovirus serology), autoimmune (antinuclear andmitochondrial antibodies), and genetic liver diseases(ceruloplasmin, alpha-1 antitrypsin level, and iron studies),was unrevealing, and an abdominal ultrasound was normal.The erythrocyte sedimentation rate, creatine kinase, andthyroid stimulating hormone were also normal. Serial liverchemistry showed persistently elevated AST levels withnormal ALT levels (Table 1). During this period of time,the patient’s fatigue resolved and she was asymptomatic.The striking elevation of AST with normal ALT levelsand negative work-up for the presence of liver disease ledto consideration of the presence of macro-aspartate ami-notransferase (macro-AST). Ultimately, a polyethyleneglycol (PEG) precipitation assay was performed, whichrevealed 89.1% PEG precipitable activity (%PPA), con-firming the presence of macro-AST.DiscussionElevated liver enzyme levels should prompt an extensive,but rational, evaluation for different causes [1], for
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