ABSTRACT:: Altered mental status represents a common cause for admission to general medicine services. Often a significant workup ensues to define an underlying etiology. When a history of bariatric surgery with small bowel resection precedes the presentation, the differential diagnosis expands. We review a patient, having prior bariatric surgery and small bowel resection, who presents with altered mental status. After an extensive workup, she was diagnosed with a rare clinical problem, D-lactic acidosis. In presenting this case, we examine the use of mnemonics in medicine and how this can assist in solving clinical problems. © 2013 Lippincott Williams & Wilkins.