Primary Shunt Hyperbilirubinæmia

Abstract

FOUR cases of jaundice were previously reported from this laboratory in which the hyperbilirubinæmia was not related to the breakdown of circulating erythrocytes nor to a defect in hepatic function¹. The hyperbilirubinæmia was familial, the serum bilirubin predominantly indirect-reacting pigment and the total urobilinogen excretion in urine and stool increased. The bone marrows showed erythroid hyperplasia and the increased marrow activity was reflected in a peripheral reticulocytosis. Erythrocyte destruction, as measured by chromium-51 red cell survival, was not a causative factor. It was suggested that the excess bile pigments were derived from marrow erythrocytes or their precursors—either by their destruction or by a direct synthesis of bilirubin from hæm or its precursors. This short cut in bilirubin production was termed ‘shunt hyperbilirubinæmia’ and was thought to represent a marked exaggeration of the normal pathway in which at least 11 per cent of bile pigments (stercobilin) are derived from sources other than the hæm of the circulating red cell². To test this postulate we have since studied four normals and one of the affected patients (A. P., case II)¹, using 2-¹⁴C-glycine as an index of hæm and stercobilin formation.