120. What is the upper limit of normal for GGT @your institution?
GGT is very sensitive for detecting hepatobiliary disease, but not very specific. Elevated levels of serum GGT has been reported in a wide variety of conditions - pancreatic disease, myocardial infarction, renal failure, chronic obstructive pulmonary disease, diabetes, alcoholism, medications such as phenytoin and barbiturates.
Why was the GGT even checked? Generally there is not reason to check one unless someone has an abnormal alk phos (to confirm the alk phos is from live and not GI or bone source).
I don't know what the GGT is from, but if there are herbals in the vitamins he takes, maybe it is that. I don't think plain green tea would do this, but perhaps there is something else in the tea as well. I don't know that obesity could cause it...mainly that causes NASH, which should cause AST and ALT to be high, not necessarily the alk phos and GGT, at least as far as I know.
I wouldn't further work this up unless there is some other evidence of something going on. It shouldn't have been checked in the first place unless there was a definite reason for doing so. You can just have the person f/u with an internist in a couple of months, perhaps have patient check the vitamins and tea he is taking to see what other herb(s) are in there, if any, and try cutting out the supplements for a couple of weeks before having the GGT rechecked. I'm not sure I'd even recheck the GGT though...
