La Revue de médecine interne
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Methemoglobinemia (MetHb) refers to the state of oxidation of the iron ion "ferrous" (Fe2+) to iron "ferric" (Fe3+) within the heme molecule that makes up hemoglobin (Hb). This state is physiological if its level remains controlled. The ferrous state of the heme molecule occurs in the event of significant oxidative stress. ⋯ Treatment is mainly based on identifying the etiology and restoring the heme molecule to its physiological state. Methylene blue is the main antidote in cases of elevated MetHb, but precautions must be taken in its use, and its physico-chemical effects must be understood. We provide an update on methemoglobinemia, summarizing its pathophysiology and clinical presentations, complementary tests and therapeutic principles.
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Periarteritis nodosa (PAN) is a vasculitis affecting medium-vessel and may be associated with myelodysplastic syndrome. This association needs a simultaneous treatment of the vascular and the hematological disease. However limited data are available on the benefit of hematological treatment, and in particular allogeneic stem cell transplantation, in this situation. ⋯ Hematopoietic stem cell allograft may represent a therapeutic option in the management of severe or refractory autoimmune diseases when the hematological indication is retained.