Shunt Bilirubin: Evidence for Two Components

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Science  15 Mar 1963:
Vol. 139, Issue 3559, pp. 1054-1055
DOI: 10.1126/science.139.3559.1054


Studies with C14-labeled glycine and δ-aminolevulinic acid as heme-bilirubin precursors in man indicate that the early labeled or shunt bilirubin consists of two fractions. Fraction 1 requires 1 to 24 hours for maximum synthesis, is not dependent on marrow erythropoietic heme synthesis, and is possibly of anabolic origin (formed by a direct pathway from heme precursors). Fraction 2 requires 3 to 4 days for maximum production, is dependent on heme synthesis, and probably has its origin in the bone marrow, as a degradation product of red-cell heme.