LITHIC ACID DIATWESIS is the term employed in medicine to designate the condition in which there is an excess of lithic (or uric) acid, either free or in cotnbination, or both, in the urine. The urine of persons who have the lithic acid diathesis is usually of a dark golden color, like brown sherry, and is more acid, of higher specific gravity, and less abundant than the urine in health. -When the urine cools, there is usually a deposit or sediment of lithates. The sediment is usually spoken of as one of Iithate (or urate) of ammonia, but in reality it consists mainly of lithate of soda mixed with lithates of ammonia, potash, and lime. Its color varies according to the amount and nature of the urine-pigment which tenaciously adheres to it, so that its tints vary from a whitish yel low to a brick-dust red, or even a deep purple. Persons seeing these deposits in their urine when it has cooled are very apt to believe that they may aggregate and harden in the bladder, and form a stone. Such fears may, however, be relieved by heating the urine containing the sediment to the temperature of the interior of the body (about 100°), when the fluid will resume its original clearness, and the sediment will disappear.
The color of the deposit is of considerable importance in determining its value as a morbid symptom. Tawny or reddish sediments of this kind are frequently the result of mere indigestion or a common cold; the yellowish-white ones deserve more attention, as they arc believed frequently to precede the excretion of sugar through the kidneys. Thc pink or brick-dust sediments are almost always associated with febrile disturbance or acute rheumatism; and if these sediments are habitual, without fever, there is most probably disease of the liver or spleen. If the urine is very acid, a portion of the Mille
acid is sepamted from its base, and shows itself, as the fluid cools, in a free crystallized state, resembling, to the naked eye, grains of cayenne pepper, but appearing under the microscope as rhombic tablets. This free lithic acid is far less common than the Iithates, and does not dissolve on the application of heat.
The persons who suffer from this diathesis are chiefly adults beyond the middle age, and of indolent and luxurious or intemperate habits. A_s the formation of lithic deposits is due to over.acidity of the urine, alkalies are the medicines most commonly prescribed, and the preparations of potash are far preferable to those of soda, because lithate of potash is perfectly soluble, and will pass off dissolved in the urine, while lithate of soda is a hard, insoluble salt.
Regimen is, however, of far more use than medicine in the lithic acid diathesis. The patient should dine moderately and very plainly, avoiding acid, saccharine, and starchy matters and fermented liquors. The skin should be made to act freely by friction, and by occasional warm or daily tepid baths. Warm clothing must be used; plenty of active exercise must be taken in the open air; and the healthy action of the bowels and liver duly attended to. It must be recollected that the lithates axe sometimes thrown down, not from undue acidity of the urine, but simply from that fluid not containing the due quantity of water to hold them in solution. In such cases a tumbler of cold spring-water taken night and morning will at once cause the cessation of this morbid symptom.