The Distribution of Phosphoric Acid in Normal Human Blood

In the last few years considerable evidence has accumulated to show that the lipoid compounds of phosphoric acid of the type of lecithin are probably of great importance in the metabolism of the fats. For example a marked increase has been observed in lecithin in the blood and particularly in the corpuscles during fat absorption (1). In those pathological conditions where the blood lipoids are abnormal, as in diabetes (2) and anemia (3) the values for lipoid phosphorus follow in general those for total lipoids. The increase in fat which takes place in the blood of hens at the time of egg production has been found to be accompanied by increased lipoid phosphorus (4). Then there is the very significant observation of Meigs and Blatherwick (5) that during the secretion of milk in cows the blood leaving the milk gland contained less lipoid phosphorus and more inorganic phosphorus than the blood entering the gland. Also that the decrease in lipoid phosphorus was sufficient to account for the fat of the milk-clearly indicating that the milk fat originated in the lipoidphosphorus compounds of the blood. On the other hand, in very severe diabetic lipemia (6), the increase of lipoid-phosphoric acid compounds’ was relatively less than that of some of the other lipoid constituents; e.g., cholesterol. The question arose whether the reason for the relatively low value may have been the lack of phosphoric acid available for lipoid combination. This involved the general problem of the relation of the lipoid phosphoric acid to other forms of organic phosphoric acid in the blood. These and