Tammy was the preoperative nurse for a patient who was planning to undergo a bariatric procedure. In the weeks prior to the day of surgery, the patient had a complete bariatric pre-surgical work up, including a full set of labs with results in the normal range. When I, as the anesthesiologist, came to see the patient in the PSCU, Tammy told me the patient did not feel well and was fairly fatigued. She had no other concerning symptoms and did not have a fever, just a general malaise. Tammy suggested we recheck her chemistry panel via a lab draw prior to surgery even though her labs were normal two weeks prior. The patient was on a strict liquid diet for the several days prior to the planned bariatric procedure, so it made sense that she could have been presenting with an electrolyte abnormality. We delayed the start of the case, and a point-of-care test showed a dangerous hyponatremia and hyperkalemia. To confirm the electrolyte abnormalities, I ordered a STAT lab draw. The potassium was normal upon lab recheck, but the sodium was confirmed as critically low. The patient’s surgery was canceled, and the patient was admitted for correction of her hyponatremia. Tammy’s careful assessment and attention to detail during the preoperative period averted a possible poor outcome for this patient.