Bro, in all honesty, I don't know much about it. I have never had that level checked on my blood work.

I believe it's used to measure renal excretion. Which with abnormal levels can be a sign of abnormal kidney function. I'll do some checking in some folders to see if i can dig up something; but none the less, just mention abnormal kidney function to your doc and see if (S)he thinks it's a possible cause.
I'll let you know if I dig up any info.

BUN and Creatinine are levels I have checked for kidney function.

Did your doctor give any explaination for possiblities?