Dan,
Good question. I use BUN all the time in the inpatient setting, spec in diagnosing acute kidney injury. Outpatient not so helpful, although once in a while it really helps.
BUN is also part of the MDRD GFR and CKD EPI GFR equations, which improve our evaluation of renal disease.
As part of a panel, it's cost is literally pennies, and I suspect it would cast more to remove it from the panels than it would save by doing so.
