Utilization of the quantitative assay of lipoprotein X in the differential diagnosis of extraphepatic obstructive jaundice and intrahepatic diseases.

Quantitative determination of LP-X, abnormal serum low density lipoprotein, was performed on the sera of 620 patients with jaundice in two medical centers, one in Oklahoma City, Oklahoma, and the other in Birmingham, England. The results of serial assays over a period of 5 to 8 days after patient admission to hospital or after onset of jaundice, if this occurred in hospital, correlated best with the type and management of jaundice. In some cases of early cholestatic disease of extrahepatic origin LP-X may be absent, but after the observation period it was found that only 1 of 81 (98%) patients with obstruction of the extrahepatic bile duct system remained negative. Of the remainder, 74 (91%) had or developed levels of LP-X exceeding 300 mg per 100 ml. In addition, 43 (88%) of 49 subjects followed serially showed increases in LP-X concentration, with no change in 3 patients. Of 539 subjects with intrahepatic disease, 14 (26.5%) were LP-X positive and 27 (19.4%) of these had initial LP-X levels higher than 300 mg per 100 ml. During the follow-up period, 35 (74%) of 47 patients with intrahepatic disease showed a reduction of LP-X; of the remaining 12 patients 4 had mitochondrial antibody-positive primary biliary cirrhosis, and 6 had severe cholestasis associated with acute infectious hepatitis and high aspartate transaminase levels. Similar figures for alkaline phosphatase showed less consistent changes during the follow-up period. In this retrospective appraisal the trends and absolute levels of LP-X, in addition to the use of similarly followed levels of the routine liver function tests, allowed better differentiation of jaundice requiring surgical correction from that remediable by medical means exclusively than did the use of the routine liver function tests alone. In addition, LP-X is specific for liver dysfunction, whereas other routine liver function tests are not.