An increase in suicide cases by sodium nitrate and sodium nitrite ingestion has been noted in the scientific literature. We report on the possible impact of nitrate/nitrite-caused methemoglobinemia on carboxyhemoglobin measurement by spectrophotometric methods. Elevated methemoglobin saturation may result in insufficient reducing agents to convert methemoglobin into deoxygenated hemoglobin, affecting the measured total hemoglobin and carboxyhemoglobin saturation. We highlight four cases where the cause of death was attributed to sodium nitrate or sodium nitrite ingestion. The possible impact of the nitrate/nitrite-caused methemoglobinemia on the carboxyhemoglobin saturation as measured by spectrophotometry is discussed. Further studies are needed to identify a causal relationship between nitrate/nitrite-caused methemoglobinemia and carboxyhemoglobin saturation as measured by spectrophotometric methods.

中文翻译：

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在致命的硝酸钠和亚硝酸钠病例中高铁血红蛋白对碳氧血红蛋白饱和度测量的影响

科学文献指出，因摄入硝酸钠和亚硝酸钠而自杀的病例有所增加。我们报告了硝酸盐/亚硝酸盐引起的高铁血红蛋白血症对分光光度法测量碳氧血红蛋白的可能影响。高铁血红蛋白饱和度升高可能导致还原剂不足，无法将高铁血红蛋白转化为脱氧血红蛋白，从而影响测量的总血红蛋白和碳氧血红蛋白饱和度。我们重点介绍四起因摄入硝酸钠或亚硝酸钠而导致死亡的案例。讨论了硝酸盐/亚硝酸盐引起的高铁血红蛋白血症对分光光度法测量的碳氧血红蛋白饱和度的可能影响。需要进一步的研究来确定硝酸盐/亚硝酸盐引起的高铁血红蛋白血症和通过分光光度法测量的碳氧血红蛋白饱和度之间的因果关系。