Bilirubin Production from Non-Erythroid Sources
It has become clear over the past several years that a small but significant portion of the total bilirubin production is derived from sources other than the hemoglobin of red blood cells. In retrospect this is not surprising since bilirubin is the product of the degradation of heme, and heme is present in virtually all tissues of the body in the form of a number of enzymes and cytochromes, myoglobin in muscle and hemoglobin in red cells. Quantitatively, most heme is present in red cell hemoglobin. The second richest source of heme synthesis is the liver. Not surprisingly, therefore, most of the bilirubin produced under normal conditions is derived from erythroid and hepatic sources, although there is presumably a small contribution from other tissues as well.
KeywordsBile Pigment Ineffective Erythropoiesis Acute Intermittent Porphyria Plasma Bilirubin Bilirubin Excretion
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