Abnormal LFT

Question: A graduating gastroenterology fellow is found to have an AST of 46 (upper limit normal 40) and ALT of 29.  Just after receiving his diploma, he leans over to you and asks, “what should I do about that?”  Well, what should you do?

A. check for viral hepatitis

B. punch him in the arm again

C. recheck LFT in 1 month

D. obtain a liver biopsy

Answer: Congratulations, first of all, to the graduating fellows.  By now, all of us should be well versed in the evaluation of abnormal LFT.  A good history taking is paramount; this will allow you to form pretest probabilities of several diagnoses.  Alcohol use, medication list (including herbs and weight loss substances), history of blood exposure, origin of ancestry etc.  In this case, the entire history is unremarkable, and we are left with the mild AST elevation.

The textbook, and board exam for that matter, tells you to repeat the LFT profile after 1-3 months, as long as there’s no reason to suspect any of the common causes of hepatitis.  This is a mild elevation of AST only, and is likely to be 1) normal at the next draw or 2) an acceptable standard deviation away from the mean.

It may be too soon to check for viral hepatitis, particularly if you’ve identified no risk factors for HBV and HCV.  If AST is consistently elevated, go ahead and check.  A liver biopsy is obviously not the next step.  Recall that muscle is another source of AST, so if the fellow was recently given a celebratory punch in the arm, that may be it.  (And for the record: a second punch is considered safe).  Good luck out there!

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