Comparison of platelet count and platelet protein methods for determination of platelet MAO activity

Platelet monoamine oxidase (MAO) activity in 10 normal volunteers was studied as a function of platelet protein or electronically-determined platelet counts. Comparisons of the two methods were made for samples assayed on the same day as well as one week later. The MAO activities resulting from both methods were significantly correlated and reproducible but the results of the platelet count method were, in most instances, slightly but significantly more reliable than the platelet protein method. The relevance of these results to the controversy concerning platelet MAO activity in schizophrenia is discussed.