Emoglobin formation. Pathophysiology of oxidation of hemoglobin to methemoglobin and its reversal to hemoglobin by reductase along with the elements involvedCEN Case Reports (2021) 10:336donating electron to Fe3+, and thus, the ETB custom synthesis conversion to Fe2+ maintains a methemoglobin level below two [7]. CDK12 Source dapsone (four,4-diaminodiphenyl sulfone) is really a sulfone group antibiotic and potent anti-inflammatory agent [8]. Additionally to PJP pneumonia therapy and prophylaxis, dapsone is utilised within the treatment of leprosy, bullous illnesses like dermatitis herpetiformis, and ulcerative colitis, prevention of toxoplasmosis, as well as as a second-line agent in immune thrombocytopenia [92]. Dapsone hydroxylamine (N-hydroxylated metabolite of dapsone) is a potent oxidant having a prolonged half-life and is responsible for numerous adverse effects like methemoglobinemia, dose-dependent hemolytic anemia, dapsone hypersensitivity syndrome, and thrombosis [13, 14]. Quite a few drugs may cause methemoglobinemia, as shown in Table 1 [3, four, 15, 16]. In a retrospective study by Ash-Bernal et al., dapsone accounted for about 42 of situations of methemoglobin, producing it one of the most frequent result in of acquired methemoglobinemia [4]. Although dapsone-induced methemoglobinemia is popular, the absence of standard symptoms (such as in our patient) could make the diagnosis hard to establish, prompting a higher degree of suspicion in individuals who present with respiratory distress in the setting of standard cardiopulmonary function. Methemoglobinemia causes symptoms within a dose-dependent manner, also as by the speedy acceleration of its formation, and these symptoms may be variable. For instance, a lifelong methemoglobinemia patient can be asymptomatic, while sufferers with abrupt acquired methemoglobinemia on account of drugs and/or toxins can develop fulminant symptoms. Methemoglobin concentrations of 10 to 20 are usually tolerated well; even so, in sufferers like ours, subtle nonspecific symptoms can be observed, possibly because of underlying cardiac illness. Most patients present with nonspecificTable 1 Popular acquired causes of methemoglobinemiaMedications/Chemicals: Acetaminophen p-amino salicylic acid Chloramines Chloroquine/ primaquine Dapsone Local anesthetic agents Methylene blue Metoclopramide Nitrites/Nitrates, Nitric oxide, Nitroprusside Rasburicase Rifampin Sulfonamides Diseases: Sepsis Gastrointestinal illness Sickle cell illness Used as therapy as wellsymptoms like headache, dyspnea, fatigue, dizziness, and mental status modifications [15, 17]. Levels greater than 1.five g/dL or 15 are often associated with cyanosis, as well as the reduce degree of 13.9 may perhaps clarify why our patient did not present using the classic finding of cyanosis [7, 18]. Dyspnea, nausea, and tachycardia happen at methemoglobin levels of 30 or far more. Lethargy, stupor, and deteriorating consciousness take place as methemoglobin levels method 55 [3]. Higher levels might trigger cardiac arrhythmias, circulatory failure, and death ( 70 ), which is a possibility having a missed diagnosis. Commonly in sufferers with nephrotic syndrome, the most widespread causes of respiratory distress are fluid overload, secondary to ineffective diuresis, or acute kidney injury and/or pulmonary embolism, which have been explored initially. Similarly, an acute infective pulmonary course of action in an immunosuppressed patient or acute coronary syndrome in our patient with a complex healthcare history was ruled out. Though they are vital, this complicated healthcare history might have contribute.