Apoenzyme activities of erythrocyte transketolase, glutathione reductase, and glutamic-pyruvic transaminase during pregnancy.

The erythrocyte apoenzyme activities of transketolase, glutathione reductase, and glutamic-pyruvic transaminase were determined in 236 pregnant women during the first or second trimester and again during the third trimester. There were no differences in erythrocyte glutathione reductase and erythrocyte glutamic-pyruvic transaminase activities during these two periods. In contrast, erythrocyte transketolase decreased significantly in the third trimester. No statistically significant correlations were found between levels of activity for the various enzymes and dietary intakes of protein, vitamins or calories. The percent of subjects with low erythrocyte transketolase activity (a value one standard deviation or more below the mean initial value) increased significantly during the third trimester. The percent of subjects with low erythrocyte glutamic-pyruvic transaminase activity was significantly reduced during the third trimester although the mean apoenzyme level did not change. Vitamin deficiencies as measured by enzyme stimulation tests tended to occur less frequently among subjects with low enzyme activities but in no instance was there a statistically significant difference. Hence, no association could be found between apoenzyme activity and the incidence of vitamin deficiencies.