Studies of Calcium and Phosphorus Metabolism

Abstract

In the course of our studies in calciulm metabolism evidence has steadily accumulated that the metabolism of acid-producing substances plays an important r6le in influencing the assimilation and excretion of calcium. This effect, however, has not been adequately studied in man, and in other studies of calcium exchange the potential acidity or alkalinity of foods and medication has largely been neglected.It is the purpose of the present investigation to follow the effect of food-stuffs and inorganic salts on calcium metabolism with relation to their potential acidity (after oxidation) referred to the hydrogen ion concentration of the blood.Studies in rickets for some time have indicated the importance of acidity to the assimilation and storage of inorganic salts in bone. Thus, McClendon (1) noted that the addition of alkali to a diet increased its power to produce rickets and, conversely, Zucker, Johnson, and Barnett (2) reported that the change in acidity of diets from the alkaline toward the acid side of neutrality might result in healing of the rachitic lesions.Much work, too, has been done upon the effect of administered acid on the mineral excretion. The experiments of Givens and Mendel (3) and of Givens (4) upon the effect of base and acid on the general metabolism tended to minimize variations in calcium excretion resulting from this factor. Subsequently, Goto (5), using rabbits, demonstrated depletion of the skeleton by repeated doses of hydrochloric acid. Lamb and Evvard (6) demonstrated increased urinary calcium

Studies of Calcium and Phosphorus Metabolism

“…After several weeks on a low calcium diet, also, as described elsewhere (26), ingestion of large amounts of NH,Cl was associated with slightly decreased levels for calcium and phosphorus in some cases, and ingestion of NaHCO3 with increased levels for serum calcium. In all experiments, however, on ingestion of acid or alkali on high or low calcium diets, the total range of variation of many determinations for any given individual was never greater than 1 mgm.…”

“…In patient D. A. (Case IT, period XV), described elsewhere (26), the ingestion of large amounts of NH4Cl after the subject had been on a low calcium diet for several weeks, resulted in a fall of slightly more than 1 mgm. in serum calcium.…”

Studies of Calcium and Phosphorus Metabolism

“…The ammonia mechanism is not called into use in this case of hyperthyroidism and the increased acid excretion is apparently completely taken care of by other factors. In other ex-periments Farquharson, Salter, Tibbetts, and Aub (4) found that calcium and ammonia excretion-increased together in response to chloride ingestion and neither responded much to increased phosphate ingestion. Here, however, there is no such parallelism.…”

“…On the other hand studies from this laboratory (4) show that the increased calcium excretion found in the feces in hyperthyroidism is not present in the disordered metabolism of acidosis.' This discrepancy seemed important, but perhaps not fundamental, for the increased fecal excretion in hyperthyroidism may merely be an expression of increased intestinal rate and increased excretion of gastrointestinal juices.…”

“…These various mechanisms are to a certain extent simultaneously called into play. The fourth is often the least affected by acid diets (4). It is, therefore, fair to assume that if the marked increased excretion found in hyperthyroidism is due to an acidosis, there must also be obvious stimulation of the other three mechanisms.…”