Joan,

Thank you, thank you, thank you!!! I never doubted that our doctor was correct about the 80-1 conversion, but am very glad to have the cite, nontheless.  I always knew I'd eventually come across it one day.

What's interesting (and dangerous) about using the wrong conversion factor ( 40-1 vs. 80-1) is that in converting from dexamethasone to hydrocortisone, one will end up grossly UNDERsuppressing the patient, by ending up with a number only HALF the correct one.  Conversely, in converting from hydrocortisone to dexamethasone (again, incorrectly using 40-1), one will end up grossly OVERsuppressing the patient, by ending up with a number DOUBLE the correct one. 

It took me a while to fully grasp this idea, but when I number-crunched through some examples, I realized that this was the case.  I also believe that this might be one reason why those doctors unfamiliar with dexamethasone useage and dosaging often end up inadvertently oversuppresssing their patients.   If by using the commonly accepted 40-1 number, one ends up prescribing DOUBLE the amount of medication that's required, it is no small wonder that overtreatment results.

Confusing things even further, however, is that if one tries to equate dosage amounts, by (incorrectly) converting DIRECTLY from one medication to the other, and without FIRST taking into account body mass (meter squared)----which is the way it really should be done---one actually ends up with numbers closer to the 40-1 factor.  I haven't analyzed this fully to figure out why this is the case, but believe this might be an odd coincidence due to the fact that dex. is often dosed around .25 mg/m2 (and .25 x 4 = 1). 

I guess the lesson to be learned is that it is best to start from scratch when switching medications, by utilizing recommended and accepted doses for that PARTICULAR drug.  As you can see, when one tries to convert from doses of one med. to doses of a different one, the possibility (even probability) of error is incredibly high.

Anyway, thanks again, Joan!  This one will definitely make it into my archives.