Mineral Exchanges of Man

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Abstract
The ingestion of a diet rich in calcium and phosphorus by a patient with mild hyperparathyroidism resulted in retention of these elements in approximately the proportions in which they occur in bone. During 108 days the total amount of calcium retained was 60 gm., of phosphorus 34.7 gm. and of nitrogen 70 gm. In spite of this, the ingestion of a high calcium diet for 1 year did not result in appreciable recalcification of the skeletal lesions. The daily administration of from 10 to 18 gm. of sodium acid phosphate increased the concentration of inorganic phosphorus in blood plasma and decreased hypercalcemia and hypercalcinuria. The amount of calcium and phosphorus retained was increased during the periods in which acid phosphate was ingested. These effects were temporary and ceased as soon as the administration of phosphate was discontinued. Calcium of the food was much more completely absorbed than calcium administered in the form of lactate or gluconate. The ingestion of a low calcium diet was attended by a marked decrease in the amount of calcium excreted in the urine. The exchanges of magnesium were not materially influenced by the state of the calcium balance. The ingestion of large amounts of sodium acid phosphate caused a decrease in the amount of magnesium excreted in the urine and in several instances an increase in the excretion of magnesium in the feces. Extra phosphoric acid, administered as sodium acid phosphate, was excreted chiefly in the urine. Provision was made for the elimination of this excess of acid by, a) increase in the titratable acid in the urine, b) decrease in the excretion of undetermined acid in the urine (bicarbonate plus organic acid) and, c) by an increase in excretion of fixed base (sodium) in amounts equivalent to those present in the sodium acid phosphate which was ingested. The excretion of fecal phosphorus showed a slight increase as a result of administration of phosphate, and there was usually a concomitant increase in the excretion of fecal fixed base in the form of calcium and magnesium. There was little or no correlation between excretion of phosphorus in the feces and the fecal excretion of sodium and potassuim. Sodium ingested with the food, as a solution of sodium chloride and as sodium acid phosphate was eliminated almost quantitatively in the urine. Equilibrium between intake and outgo of potassium was maintained throughout the period of observation.

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