Phadebas amylase test kits.

The observation by Hafkenscheid (1) thatPhadebas Amylase Test kitswith bovine serum albumin (BSA) gave lower results than those without BSA is, as he infers, evidently caused by differences between the standard curves supplied by the manufacturer. We found rather better agreement for plasma assays between the oldand new-formulation tablets (2). However, we routinely check the calibration curve for each lot of tablets against the stated values of Phadebas Reference Serum and Phadebas ACR (high amylase) serum. If there is a small discrepancy between our calibration line thus derived and that supplied by Pharmacia, we use our own line when it has been checked and we are satisfied that it is correct for our conditions. We have previously discussed this point (3). In our comparison of the old and new tablets (2), we made a slight alteration to the calibration linefortheoldtablets, but found it to be unnecessary for those with BSA. This had the effect of slightly lowering the results with the old tablets. It would be interesting to know whether Hafkenscheid has any assay results for the Phadebas control sera by the two methods. In our opinion, it would be wrong to introduce a new reference range for the tablets with BSA on the basis of the evidence now available. The discrepancy could just as easily have resulted from a faulty calibration line fr the old batch of tablets.