LP-X test in sarcoidosis patients with liver involvement: comparison with other liver function tests.

In the serum of many patients with sarcoidosis, alkaline phosphatase activity is increased due to sarcoid liver involvement. A study was carried out of various tests expressing intrahepatic cholestasis in 26 patients with sarcoidosis, 18 of them with a positive liver biopsy and 8 with a negative liver biopsy. SAP was elevated in 23% of the patients and its thermoresistance pointed to an hepatic origin. The predictive value of a positive test (PV-positive, the percentage of times that a positive test is in agreement with an involved liver) and the predictive value of a negative test (PV-negative, the percentage of times that a negative test will detect a nondiseased liver) were calculated. LP-X test is more reliable than SAP, which in turn is better than CB, BSP retention, and gamma-glutamyl-transpeptidase, in that order. LP-X seems to be more specific and more sensitive than alkaline phosphatase for predicting liver involvement in sarcoidosis.