PHOSPHATIC DIATHESIS, in medicine, designates the condition in which there is a tendency in the urine to deposit:white gravel. . As the deposit of lithates (see LITHIC ACID DIATHESIS) depends upon an excessive acidity of the urine, so that of the phosphates is determined by the opposite condition—namely, by deficient acidity, or by positive allta leseense. Alkalescence of the urine may occur from two distinct causes—viz. (1) from the presence of the carbonate of a fixed alkali (potash, or soda), or of alkaline phosphate of soda (see PHOtiPlIATES in physiology); or (2) from the presence of the_carbonate of the volatile alkali, ammonia, which is due to the decomposition of urea. This decomposition is due to the fermenting action of the mucus of the bladder on the urea, and is explained Carbonate of Urea. Water. Ammonia.
by the + 2110 = 2(N113,C0a). • The white gravel which is deposited in the second of these conditions—viz., when the urine contains carbonate of ammonia, is composed of minute shining prismatic crystals of the triple phosphate of ammonia and magnesia, whose formula is given in the article PILOSPIIATES. This salt is formed as follows: Healthy urine contains phosphate of mag nesia in a state of solution. however, the urine become alkaline front the decompo sition of the urea, a portion of the ammonia combines with the phosphate of magnesia, and forms the triple salt which is insoluble in the urine, which has now become alkaline. With this triple phosphate, there is almost always an admixture of phosphate of lime (3CaO,P0,) in the form of an amorphous precipitate. The tendency to deposit the mixed phosphates (triple phosphate and amorphous phosphate of lime) is especially observed in cases of disease or injury of the spinal cord, and in disease of the bladder, particularly in chronic inflammation of its mucous coat. Upon allowing urine of this kind, which is usually pale in color, to stand for some time an iridescent tiltu or pellicle generally forms upon its surface, which, when examined under the microscope, is found to consist mainly of the salts we have described. Such urine speedily becomes putrid,
and evolves a strong ammoniacal odor.
The above is by far the most common form of the phosphatic deposits, but, as has been already stated, time urine may become alkaline from the presence of the carbonate of potash or soda; and then, no ammonia being present, in place of the triple salt, there is a deposition of amorphous phosphate of lime, or in rare cases, of a crystalline stellar phosphate, whose composition, according to Dr. Bence Jones, is represented by 2Ca0,11 0,P06 (foam. of Chem Soc. vol. 15). Iii these cases the urine is alkaline, pale, copious, slightly turbid, of low specific gravity, and of a peculiar odor. This urine makes red dened litmus paper permanently blue; while ammoniacal urine causes only a temporary change in the color of the same test-paper. As the urine cools, and sometimes even in the bladder, the white sand is deposited, occasionally giving the last portion of the excreted urine a milky appearance. During perfect health, the urine often becomes tem porarily alkaline during the act of digestion (when the gastric juice is especially acid)ti but as a general rule, the tendency to alkalescenee from a fixed alkali, and therefore to phosphatic deposits, is associated with general debility. These deposits occur for the most part in sallow, languid, unhealthy-looking persons, whose vital energies have been depressed by mental anxiety, by insufficient food, or by sexual excesses.
In both forms of alkaline urine, and therefore of phosphatic deposits, a generous diet and tonics, such as bark, wine, and the mineral acids (given before meals), are of great service; and opium is usually of great value, if judiciously administered. Small doses of benzoic acid, twice or thrice a day. with the view of restoring the acidity to the urine; and the occasional washing-out of the bladder with tepid injections, have been also found serviceable in the ammoniacal form of the disease.