Patient is a 28 year old female without hypertension, hyperlipidemia. Creatinine has been within normal limits but slowly trending up over the past 5 years, starting at 0.4 and is currently at 0.9. Medications are orthotricycline lo, 25mcg synthroid, Adderall IR 5mg as needed. Pt takes Tylenol/motrin PRN for aches and pains, not on a regular basis.What could be causing this trending creatinine in an otherwise healthy female?