Plasma choline concentration in humans fed parenterally.

Choline is an essential nutrient for some mammals; it is used for membrane and neurotransmitter synthesis. We analyzed plasma samples, obtained periodically during TPN therapy, for choline concentration. Malnourished patients referred to a nutrition support service were prospectively assigned to be treated with daily infusions of amino acids with, and without, supplemental daily infusions of lipid emulsion for a period of 1 wk. After the first week, all subjects received intravenous lipid, and most were offered enteral food supplements. Initial plasma choline concentrations in the 25 malnourished patients were significantly lower than those measured in plasma samples from 23 hospitalized patients known to be eating well (6.5 +/- 0.6 vs 9.7 +/- 0.7 nmol/ml; mean +/- SEM; p less than 0.001). During the first week of TPN therapy, plasma choline concentrations in the lipid-restricted group tended to decrease (from 7.3 +/- 1.0 to 4.7 +/- 0.5 nmol/ml; mean +/- SEM; p less than 0.05), while in the lipid-supplemented group plasma choline tended to increase (from 5.6 +/- 0.5 to 6.2 +/- 0.7 nmol/ml; mean +/- SEM; p less than 0.05). Plasma choline concentration increased during wk 2-4, when all patients were treated with lipid emulsions, and some were offered enteral foods. We conclude that malnourished humans who eat no choline have diminished stores of plasma (and possibly tissue) choline.