EPHEDRINE NEPHROLITHIASIS ASSOCIATED WITH EPHEDRINE USE. B.A. Costello 1 ; 1 Mayo Clinic, Rochester, MN LEARNING OBJECTIVES: 1) Awareness of nephrolithiasis as a potential complication of ephedrine overuse. 2) Recognition of importance of asking patients about over-the-counter (OTC) supplements. CASE INFORMATION: A 34 yo female was referred to our instution following a diagnosis of nephrolithiasis. She reported 2±3 similar episodes/yr over the past 20 years. Prior to transfer, she was found to have a 5mm stone in her left ureter. Upon admission, analgesia and hydration were provided; urine was strained for debris. 24h urine for citrate, oxalate, calcium, uric acid, and cystine was normal. She passed a stone which was analyzed and found to be composed of ephedrine. Upon further questioning, she reported long-term use of ephedrine and pseudoephedrine for nasal congestion. In addition, she had recently been using herbal supplements for weight loss. Although she was unaware, we found an additional ephedrine stone on this patient in our referral lab files. We advised her to discontinue all these agents. She has not had further episodes after 6 months of follow-up. DISCUSSION: Ephedrine nephrolithiasis has previously been reported in patients consuming ephedrine or ephedrine-containing herbal preparations (1, 2) . Our case suggests that chronic use of ephedrine can lead to recurrent nephrolithiasis. Herbal supplements used for dietary purposes commonly contain ephedrine and we suspect our patient was likely receiving additional ephedrine through the supplement. In 1997, the FDA did call into question the safety of supplements containing ephedrine (3), however, they remain readily available and are sometimes 3D Surface Shaded display showing high-grade stenosis of the celiac axis and superior mesenteric artery origins.