Short-term variation in the level of alpha-fetoprotein in maternal serum

Abstract
Serial serum levels of alpha-fetoprotein (AFP) were examined over a 24-h period in six subjects. A short-term variation was demonstrated which was significantly greater than that due to the assay alone, but which showed no particular pattern. These findings may explain why an 'abnormal' AFP level frequently reverts to a 'normal' level on second sampling.