Serum F protein: a new sensitive and specific test of hepatocellular damage.

F protein is a 44-kDa protein which is found mostly in the liver and circulates at much lower concentrations in the serum. Serum F protein has been measured, using a recently developed radioimmunoassay, in a variety of diseases and was appreciably raised only in patients with hepatocellular damage. The serum F protein concentration was a more sensitive and specific marker of liver damage than conventional liver function tests and showed a close correlation with the histological assessment of liver damage (r = 0.86, P less than 0.001). This new marker may be of value in the diagnosis and treatment of liver disease.