Abstract
Summary
A relatively simple titrimetric method for determining total cation-forming mineral elements in urine and feces is described and demonstrated to yield dependable values. Addition of fecal minerals to an otherwise constant diet in rats is shown to effect an increased urinary excretion of total cation-forming mineral elements together with a correspondingly decreased renal “net acid” excretion. The theoretical basis for this result and for analogous results of others is discussed. It is concluded that the extent to which cation-forming mineral elements are excreted in the feces rather than in urine can considerably influence the extent of renal “net acid” excretion.
Addendum: While the preceding report was in press, studies by Lennon, Lemann and Litzow(13,14) appeared, in which collective values for Na+, K+, Ca++ and Mg++ (ions derivable from cation-forming elements) in diet and feces, respectively, are calculated as a negative and positive component, respectively, of “total effective acid production” (”TEAP”) in the organism, a value which is shown normally to be balanced by renal “net acid” excretion (13). The value for fecal excretion of the cation-forming mineral elements therefore appears as a positive component of the “TEAP” value, and since the latter is normally balanced by the renal “net acid” value, it appears that the described calculation of “TEAP”(13) takes into account the influence of fecal excretion of cation-forming mineral elements on renal “net acid” excretion. However, the nature of the calculation suggests that the authors (13) are unaware of the relationships shown in Equation 2, which account for this influence. The complete operational definition proposed (13) for “TEAP” may be expressed by the following equation, in which “absorbed” designates values obtained by subtracting fecal from dietary values:
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