K Stouten1,2, J A Riedl3, M-D Levin2, W van Gelder1. 1. Department of Clinical Chemistry, Albert Schweitzer Hospital, Dordrecht, The Netherlands. 2. Department of Internal Medicine, Albert Schweitzer Hospital, Dordrecht, The Netherlands. 3. Department of Clinical Chemistry, Albert Schweitzer Hospital, Dordrecht, The Netherlands. j.riedl@asz.nl.