458 JACOB ROSEXBLOOM 



triple phosphate (ammonium-magnesium phosphate). The indigo, uro- 

 stealith, fibrin, cholesterol, silicic acid, hematoidin, magnesium urate, pro- 

 tein, blood and bacteria calculi are very rare and there is practically noth- 

 ing to be noted as regards their metabolic interest or treatment at this 

 time. It was formerly taught that most urinary stones are composed 

 of uric acid, or urates, but recent studies show that this idea is wrong, 

 and that the majority of urinary stones are composed of calcium salts. 

 These studies also show that it is impossible to determine the nature 

 of the stone by microscopic examination, that the only method is to 

 examine it chemically, and the treatment instituted should be based on 

 the character of the stone. It is especially important that those subject 

 to urinary lithiasis should be treated along the lines suggested, after the 

 nature of the stone or gravel has been determined, as it is only by this 

 procedure that we may be able to prevent the formation of new stones 

 or the further growth of the primary stone. 



II. Metabolic Studies 



Phosphaturia and Phosphate Stones 



The cardinal symptoms of phosphaturia are the presence of a cloudy or 

 milky urine, of usually an alkaline reaction, occasionally neutral or ampho- 

 teric and rarely weakly acid. This cloudy urine has interested physicians 

 from early days in the history of medicine. To understand its origin we 

 must consider certain facts regarding the metabolism of the substances that 

 form this precipitate. 



Phosphorus Metabolism 



The phosphorus in our food and in the organism is never in its molecu- 

 lar form, but always as its salts and as esters of orthophosphoric acid. The 

 salts are the primary and secondary phosphates of sodium, calcium, potas- 

 sium and magnesium, all of which can be resorbed in the digestive tract. 

 The extent of resorption of the soluble and insoluble phosphates is depen- 

 dent on the acid or alkaline reaction and the concentration of the calcium 

 and magnesium ions present, and is, consequently, very variable. Phos- 

 phoric acid is found incorporated in the molecule of protein bodies, the 

 phosphoproteins of which the chief representatives are casein of milk 

 and the vitellin of the egg yolk and as a constitutent of nucleoprotein. 



The sulphuric acid (sulphate ion) arising in metabolism from the 

 oxidation of the protein sulphur requires two cations with which it circu- 

 lates in the blood and is excreted in the urine. As the sulphate ion corre- 

 sponds to a strong acid, since a sulphuric acid in the strength here consid- 

 ered is completely dissociated, it cannot take two hydrogen ions with it 

 into the urine since an acid reaction of such a strength is not possible. 



