Free choline in human plasma analysed by simple radio-enzymatic procedure: Age distribution and effect of a meal

Ultrafiltration of plasma was shown to be a simple and rapid method to obtain a stable sample for direct measurement of free choline (Ch) in plasma by a radioenzymatic procedure. Free Ch was analysed in plasma from healthy volunteers fasted 12-15 h and 1 h after a meal. The free Ch concentration was found within narrow limits with a mean of 10.6 +/- 0.4 mumol/l in the fasted subjects and 11.5 +/- 0.3 mumol/l 1 h after a meal. The difference is significant (paired t test, P less than 0.01, n = 23). Dietary influence on the free Ch concentration in human plasma is suggested. In three newborn infants (1-3 min post partum) the Ch concentration in plasma from the umbilical vein was 24.5 +/- 1.9 mumol/l.