CHAPTER XXV 

 URINE: CALCULI 



URINARY calculi, also called concretions, or concrements are solid 

 masses of urinary sediment formed in some part of the urinary tract. 

 They vary in shape and size according to their location, the smaller 

 calculi, termed sand or gravel, in general arising from the kidney or the 

 pelvic portion of the kidney, whereas the large calculi are ordinarily 

 formed in the bladder. There are two general classes of calculi as 

 regards composition, i.e., simple and compound. The simple form is 

 made up of but a single constituent, whereas the compound type con- 

 tains two or more individual constituents. The structural plan of 

 most calculi consists of an arrangement of concentric rings about a 

 central nucleus, the number of rings frequently being dependent upon 

 the number of individual constituents which enter into the structure 

 of the calculus. However, layers quite different in macroscopical 

 appearance may be almost identical in composition. In case two or 

 more calculi unite to form a single calculus the resultant body will 

 obviously contain as many nuclei as there were individual calculi 

 concerned in its construction. Under certain conditions the growth of 

 a calculus will be principally in only one direction, thus preventing 

 the nucleus from maintaining a central location. The qualitative 

 composition of urinary calculi is dependent, in great part, upon the 

 reaction of the urine, e.g., if the reaction of the urine is acid the calculi 

 present will be composed, in great part at least, of substances that are 

 capable of depositing in acid urine, e.g., uric acid, urates and calcium 

 oxalates. 



According to Ultzmann, out of 545 cases of urinary calculus, uric 

 acid and urates formed the nucleus in about 81 per cent of the cases; 

 earthy phosphates in about 9 per cent; calcium oxalate in about 6 per 

 cent; cystine in something over i per cent, while in about 3 per cent 

 of the cases some foreign body comprised the nucleus. 



More recent analyses 1 of twenty-four calculi showed the nucleus in 

 75 per cent of them to be calcium oxalate (60 per cent) and in 25 per 

 cent to be phosphate (56 per cent). All of the calculi contained some 

 uric acid and urates, but only three gave more than 10 per cent. 



1 Kahn and Rosenbloom: Jour. Am. Med. Ass'n, 59, 2252, 1913. 



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