D to delay in the diagnosis of dapsoneinduced methemoglobinemia that is presented with subtle attributes. Considering that usage of dapsone as prophylaxis for PJP in patients with nephrotic syndrome is rare, this association has in no way been reported in the literature. It’s interesting to note that some literature suggests that methemoglobinemia itself may cause acute kidney injury possibly due to acute tubular necrosis (cast nephropathy), but there is certainly no proof that AKI can result in methemoglobinemia . Additionally, methemoglobinemia has been reported as a side impact of methylene blue therapy in patients with G6PD deficiency. Diagnosis of methemoglobinemia could be produced by a cooximeter which measures the absorption spectra of numerous various light wavelengths, in contrast with traditional pulsoxymetry which measures only 2 light wavelengths. This non-invasive strategy permits physicians to measure many abnormal hemoglobin levels constantly, and in some cases within the presence of hypoxia . Remedy is based around the severity from the illness, also as acuity or chronicity of symptoms. Chronic and healthy individuals tolerate methemoglobinemia nicely. Having said that, individuals which have acute methemoglobinemia ordinarily call for therapy, particularly if they have pre-existing anemia or underlying cardiac disease, as did our patient. Identifying the prospective supply of methemoglobinemia and prompt cessation of your source is key. In asymptomatic individuals (ordinarily with methemoglobin levels of 20 ), discontinuing the offending agent need to suffice [5, 15]. Inside the case of symptomatic and/or those with levels 30 , administration of supplemental oxygen and 1 methylene blue (intravenous or oral at 1 mg/Kg) is suggested by many research . Methylene blue operates as cofactor in transferring electron to ferric hemoglobin from NADPH [2, 5] (Fig. 1). Methylene blue is oxidized into leucomethylene blue byCEN Case Reports (2021) ten:336accepting an electron from NADPH (NADPH-methemoglobin BD2 Gene ID reductase), which it then delivers to methemoglobin (Fe3+), converting it into hemoglobin (Fe2+) . Response to therapy is generally seen in 300 min and can be redosed if needed. In extreme instances of methemoglobinemia, the addition of activated charcoal can be helpful because it decreases the absorption of dapsone and its metabolites within the gastro-intestinal tract . Becoming a drug, methylene blue has unwanted effects of its own. It can lead to nausea, diarrhea, oral dysesthesia, dyspnea, chest discomfort, excessive perspiration, hemolysis (as noticed in G6PD deficiency), CNS toxicity (monoamine oxidase inhibition) and may also interfere with co-oximetry, requiring distinct strategies for instance the Evelyn alloy process [18, 23, 24]. Riboflavin and HD2 Storage & Stability sodium ascorbate (10000 mg, oral or intravenous) could possibly be useful in some individuals [7, 25]. Very seldom, hyperbaric oxygenation and exchange transfusion have been utilized, especially in life-threatening conditions . In individuals with known history of methemoglobinemia, formation of hydroxylamine metabolite of dapsone within the liver is usually halted by adding cimetidine (Cytochrome P450 inhibitor) prophylactically [26, 27]. Other experimental therapies incorporate ketoconazole and N-acetyl cystine [28, 29]. It truly is crucial to distinguish involving methemoglobin and sulfhemoglobin, as quite a few drugs can cause either of those disorders. Point of care co-oximetry, spectrophotometry, gas chromatography ass spectrometry, or a potassium cyanide test can differentiate between the two [3.