[Varying results of different procedures for determining the FT4 concentration in serum before and after heparin administration].

After application of heparin FT4 was determined by various methods in patients undergoing hemodialysis, and the results were compared with those obtained before application of heparin. Using ultrafiltration (Amicon) and the Dow-Lepetit test a significant increase in FT4 concentration could be registered at all times after heparin application. By use of the Corning test a non-significant increase in FT4 concentration was found one hour after heparin application. When the Amerlex method was employed no change in FT4 concentrations was detectable. Most probably, the observed increase in FT4 concentration after heparin application does, in fact, occur.