Kahn and Roe's 1 report on calcium absorption from the intestinal tract in human subjects appeared just as we were beginning to make hourly serum calcium observations after the ingestion of known amounts of calcium lactate. As our studies did not confirm those made by Kahn and Roe, we have continued our work. Since then we have completed the study of seventeen normal persons, nine after the ingestion of 5 Gm. and eight after the oral administration of 10 Gm. of calcium lactate. Cases of endocrine disturbances have also been studied, but they will be reported in a later communication.
Kahn and Roe speak of the number of milligrams of calcium per hundred cubic centimeters of blood—not stating whether they mean whole blood, serum or plasma. They used a method for determination that they had previously reported.2 All calcium determinations in our series of observations were made according to