Determination of free choline in plasma and erythrocyte samples and choline derived from membrane phosphatidylcholine by a chemiluminescence method.

A sensitive chemiluminescence method for assay of choline which has been developed for analysis of erythrocyte and plasma levels of choline is reported here. This method includes a charcoal purification step which yields consistent results with plasma and erythrocyte extracts. Further, choline derived from membrane phosphatidylcholine may also be measured by an extension of this method following digestion with phospholipase D. This method has been used to study abnormal levels of erythrocyte choline that occur in cluster headache patients compared to control subjects and migraine patients. In addition, the time course of changes in plasma and erythrocyte choline following a fatty meal have been monitored. Plasma choline levels rise to a maximum between 1 and 3 h after the meal and this is followed by a rise in erythrocyte choline levels which are maximal 3 h after the meal.