Hemoglobin Toxins

Hemoglobin is susceptible to several kinds of toxins. By far the most important in terms of prevalence, seriousness, and possible fatal outcome is carbon monoxide poisoning. Carbon monoxide binds tightly to heme, dissociates slowly, and prevents oxygen binding. Causes, prevention, and treatment are reviewed. A number of drugs and environmental exposures may oxidize the iron in heme, rendering it useless for oxygen acquisition, a condition called toxic methemoglobinemia. In severe cases it is life-threatening. Its causes and treatment are discussed. A seeming paradox is that methemoglobin, deliberately produced medicinally with nitrites, can help treat cyanide or sulfide poisoning. Some sulfur compounds can bind to heme and result in sulfhemoglobinemia, a relatively mild condition.