Methemoglobinemia is a rare disorder associated with oxidization of
divalent ferro-iron of hemoglobin (Hb) to ferri-iron of methemoglobin
(MetHb). Methemoglobinemia can result from either inherited or acquired
processes. Acquired forms are the most common, mainly due to the
exposure to substances that cause oxidation of the Hb both directly or
indirectly. Inherited forms are due either to autosomal recessive
variants in the CYB5R3 gene or to autosomal dominant variants in the
globin genes, collectively known as HbM disease. Our recommendations are
based on a systematic literature search. A series of questions regarding
the key signs and symptoms, the methods for diagnosis, the clinical
management in neonatal/childhood/adulthood period, and the therapeutic
approach of methemoglobinemia were formulated and the relative
recommendations were produced. An agreement was obtained using a
Delphi-like approach and the experts panel reached a final consensus
>75% of agreement for all the questions