Congenital methaemoglobinaemia identified by pulse oximetry screening

Research output: Contribution to journalArticlepeer-review


  • Jennifer Ward
  • Jayashree Motwani
  • Nikki Baker
  • Matthew Nash
  • Gergely Toldi

Colleges, School and Institutes

External organisations

  • Birmingham Women's and Children's Hospital


Congenital methaemoglobinaemia is a rare condition caused by cytochrome b5 reductase deficiency, cytochrome b5 deficiency or haemoglobin M disease. Newborn pulse oximetry screening was developed for the early detection of critical congenital heart disease, however, it also enables the early identification of other hypoxaemic conditions. We present the case of a term neonate who was admitted onto the neonatal unit following a failed pulse oximetry screening at three hours of age. Oxygen saturations remained between 89-92% despite an increase of oxygen therapy. Chest X-ray and echocardiogram were normal. A capillary blood gas showed normal results except for a raised methaemoglobin level of 16%. Improvement was seen upon the administration of methylene blue which also resulted in an increase of oxygen saturations to within normal limits. Further investigation showed evidence of Type I hereditary cytochrome b5 reductase deficiency as a result of a CYB5R3 gene mutation with two pathogenic variants involving guanine to adenine substitutions. Although mild cyanosis is generally the only symptom of Type I disease, patients may later develop associated symptoms such as fatigue and shortness of breath. If an early diagnosis is missed these patients are likely to present later with a diagnostic conundrum and be subject to extensive investigation. This case represents the success of pulse oximetry screening in early identification of subclinical hypoxaemia in this infant. Following the exclusion of other pathologies, a routine investigation of a capillary blood gas provided the information to lead to a diagnosis which allowed for an early and effective management.


Original languageEnglish
Publication statusAccepted/In press - 8 Nov 2018


  • Pulse oximetry screening, Methemoglobinaemia