CAUSATION OF PHOSPHATURIA Our knowledge of the causes for the increased production of phos phate is scanty. Nor is it certain whether the train of symptoms ascribed to the loss is due to the lime or to the phosphatic constitu ents of the bone earth.
The following clinical clues are, however, established: The Sources of the Lime and Phosphates.—In osteomalacia, the urine contains from three to four times the amount of earthy phos phates that it normally eliminates. The phosphaturia is constant and not periodical. That the supply is derived from the bones is obvious, from the following estimate of lime salts in bone : In normal bone there is from 60.5 to 70.2 per cent. of lime salts. In lacia 29.17 per cent. In the last stages of osteomalacia 1.83 per cent.
So great is the deposit of phosphate of lime in the urine that stones form in the kidneys and even the bladder, except when disease of the kidneys checks the output, in which case the deposit of the lime salts is found in other organs.
In rickets the bones soften and bend, often to a remarkable extent, proving clinically, what has been established chemically, that the withdrawal of the lime salts is great. In these cases also turia is noticed at some time or other in the course of the disease, and the phosphates may rise to four or five times the normal amount.
Although they are not always deposited as earthy phosphates, yet they are held in solution by the large amount of lactic acid which is present in the urine.
As a link in the chain of associated conditions the following sta tistics by Neumann may be mentioned: He collected 327 cases of fracture of the bones (fragilitas ossium), these fractures having for the most part taken place spontaneously and the brittleness being due to the removal of the lime salts. Paralytic dementia occurred in 39.1 per cent. ; imbecility in 28.1 per cent. ; mania in 17.2 per cent. ; melancholia in 6.3 per cent. ; psychic insanity in 3.1 per cent. ; other forms of mental disease in 1.6 per cent.
Phosphaturia was noticed in acute meningitis by Bence Jones, and in acute paroxysms of certain forms of mania by Sutherland and Beale.
Phosphaturia has also been observed as a symptom occurring in progressive pernicious anmmia and preceding or accompany ing such debilitating diseases as phthisis, cancer, and diabetes mellitus.
These observations are yet too limited to draw general conclusions from. We are, however, in a position to connect the appearance of phosphaturia with the destruction and waste of some tissue of the body. But whether in these conditions "it is due to increased meta morphosis of nervous matter or to the irritation of a still hypotheti cal co-ordinating chemical centre," or to the influence of a disturbed condition of the nervous system upon nutrition generally, it is at present impossible to decide (Ralfe).