DAPSONE‐INDUCED METHHAEMOGLOBINAEMIA: A SOURCE OF DIAGNOSTIC CONFUSION

Abstract

SUMMARYArterial desaturation as measured using pulse oximetry may not reflect cardiorespiratory disease; other possible causes, including certain drugs, should be sought. Within the literature, examples exist of dapsone‐induced methaemoglobinaemia causing diagnostic confusion, particularly where respiratory disease is a feature. Few cases have been reported that demonstrate the potential of relatively low levels of methaemoglobinaemia to upset pulse oximetry readings. We describe three examples of dapsone‐induced methaemoglobinaemia emphasising the potential for low‐grade methaemoglobinaemia to cause diagnostic confusion. Widespread use of the pulse oximeter indicates this problem may occur more regularly, hence there is a need for increased awareness. (Int J Clin Pract 2000; 54(3): 194‐196)