Part I. The Determination of Urinary Acidity

Abstract

The following is the first of a series of communications relating to urinary excretion in cases of mental disorder with special reference to acid excretion. In this paper it is proposed only to deal with the make-up of urinary acidity and the methods for the determination of the acid characters. It is well known that respiratory regulation constitutes the first line of defence against change of body reaction, and that the kidneys afford the second protection against alteration by variations in the acid-base ratio of the urine. It is also fully established that urinary acidity is dependent on the nature of diet ingested, but it is not so well recognized that the urinary reaction is also dependent on the adequacy of the respiratory compensatory mechanism, and it would appear that those interested in dietetics and chemical effects on urinary acidity have not appreciated sufficiently the significance of the physiological influences, and those concerned with the respiratory side have been apt to disregard the influence of diet. The organism promptly defends itself against alkalinity by the excretion of bicarbonate, whether the alkalinity be due to ingested alkali or excessive exhalation of acid (CO2), and this excretion of bicarbonate appears to be independent of any particular renal threshold for bicarbonate. The response of the organism to acidity, however, is a much longer process, and in this case the kidney compensation takes the form of retention of base by ammonium base production and the retention of bicarbonate by alteration of the ratio of mono- and dibasic phosphate excreted according to the equation—