I am sorry to hear of the problems that you are encountering. You certainly do not need any more!
The ICD9 code is a reimbursement code that your physician provides when billing insurance. Any aspect of your problem is a reasonable heading under which to bill. I assume that your magnesium level is abnormal. Lasix does eliminate magnesium from your body and this may be what is being addressed. I am not sure whether your chemotherapy figures into this or not. I think that you deserve an explanation from the nephrologist. Give this physician a call.
Good luck with it all!
S.A.Liroff, M.D.