A pulse oximeter is an easy, painless and non-invasive device to measure blood oxygen saturation (SpO2). Usually, SpO2 is comparable to oxygen saturation by arterial blood gas (SaO2). We report a case of term infant presented with respiratory distress and low oxygen saturation measuring with a pulse oximeter. Respiratory disease and congenital heart disease were excluded. Discordance of oxygen saturation was presented. His blood was obtained to check methemoglobin level and hemoglobin (Hb) variants. Hb Lansing was detected. In addition to report the first neonate with Hb Lansing in Thailand, we draw attention to the condition as a cause of spurious low oxygen saturation. The discrepancy of oxygen saturation between pulse oximetry and arterial blood gas necessitates investigations for hemoglobinopathies.

Keywords: Hemoglobinopathy, Hemoglobin Lansing, Discordance of oxygen saturation