ARTIFACTUAL HYPOXEMIA IN PATIENTS WITH HYDROXYUREA-INDUCED BLUE LUNULA FINGERNAILS

TOPIC: Pulmonary Manifestations of Systemic Disease TYPE: Fellow Case Reports INTRODUCTION: Hydroxyurea is an antimetabolite that acts by inhibiting synthesis DNA. In addition to cancer therapy, it also used treat sickle cell anemia. However, daily use hydroxyurea not without risk, and one the lesser-known side-effects discoloration nails--specifically melanonychia (brown lines) blue lunula (nailbed crescents). The latter finding extremely rare; only 2 case reports exist in literature regarding lunula, but neither addresses its effects on oxygen saturation measurements. It a well-established fact black, green, nail polish can falsely lower pulse oximetry readings. our patient, her at base fingernails caused similar artifact. Our highlights need for recognition this rare phenomenon avoid unnecessary workup hypoxemia. CASE PRESENTATION: A 69-year-old black woman with anemia liver/kidney transplantation was admitted from clinic unexplained February 2021, patient acute chest syndrome started 500mg BID. Six weeks later, she noticed turning base. Except occasional "windedness" exertion diarrhea another medication, otherwise feeling well. clinic, found be 80-88% which prompted admission hospital given immunocompromised status. CTPA negative pulmonary embolism. Hemoglobin 10.4g/dL. An ABG room air showed mild metabolic acidosis respiratory compensation, normal oxygenation: 7.3/31/102/17/98%. We varied based placement oximeter probe tip fingernail (no discoloration) (blue crescent), so desaturation test ordered sensors placed both finger forehead. Surprisingly, upon exercise, desaturated 77% while forehead remained 99%. For reason, diagnosed artifactual hypoxemia lunula. DISCUSSION: Among hydroxyurea-induced diseases, most common. This presents diffuse or longitudinal brown stripes center nailbed. Melanonchyia associated because color does affect Blue very finding, literature, these do mention effect saturation. Given known interfere readings, unreasonable assume cause erroneous saturations. CONCLUSIONS: report heighten awareness among pulmonologists they medical when confronted scenario. REFERENCE #1: Jeevankumar B, Thappa DM. due hydroxyurea. J Dermatol 2003; 30: 628–630. #2: Usküdar Teke H, Erden A. related Turk Haematol. 2013 Mar;30(1):100-1. doi: 10.4274/tjh.2011.0016. Epub Mar 5. PMID: 24385770; PMCID: PMC3781656. #3: Rubin AS. Nail Anesthesiology. 1988 May;68(5):825. 10.1097/00000542-198805000-00049. 3369739. DISCLOSURES: No relevant relationships Ching-Fei Chang, source=Web Response, value=Consulting fee Removed 04/22/2021 Response Dafang Chen, Sahar Samani,