Journal Article

A 5-Hour-Old Male Neonate With Cyanosis

Melkon DomBourian, Alok Ezhuthachan, Amitai Kohn, Brian Berman and Elizabeth Sykes

in Laboratory Medicine

Published on behalf of American Society for Clinical Pathology

Volume 46, issue 1, pages 60-63
Published in print February 2015 | ISSN: 0007-5027
Published online August 2015 | e-ISSN: 1943-7730 | DOI:
A 5-Hour-Old Male Neonate With Cyanosis

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Methemoglobin (MetHb) is a form of hemoglobin in which heme iron is oxidized and unable to bind oxygen; its normal basal production is counteracted by an efficient MetHb-reduction pathway. The causes of methemoglobinemia are classified as congenital or acquired. Shortly after his birth, the 5-hour-old male Caucasian neonate, whose case we present herein, developed central cyanosis that was unresponsive to supplemental oxygen. Oxygen saturation as determined via pulse oximetry was normal. In contrast, blood gas testing by multiwave CO-oximetry indicated decreased fractional oxyhemoglobin and an elevated MetHb fraction. The patient was subsequently diagnosed with a congenital cytochrome b5 reductase deficiency. This case emphasizes causes of methemoglobinemia and differences among analytical methods used to measure oxygen status when MetHb is present.

Keywords: clinical chemistry; congenital methemoglobinemia; cytochrome b5 reductase; pulse oximetry; CO-oximeter; arterial blood gas

Journal Article.  1870 words.  Illustrated.

Subjects: Haematology

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