According to my lab sheet less than 60 is impaired renal function and greater than 80 is normal renal function. Mine runs in the 40s. Even though 84 sounds low according to lab values it is normal. Is your creatinine elevated? Do you have low blood albumin or protein in your urine? I would think a low protein diet and cellcept would take care of things but if you have problems I would consult a nephrologist.
DX: Kidney Disease, (? Lupus Nephritis) 2002
DX: Raynaud's Phenomenon and Lupus (SLE & Class V Lupus Nephritis) 2005
DX: Anorexia and Hypokalemia 2006
meds: plaquenil, amiloride, klor-con