69 



many, however, who hold that easts are always the products of 

 an inflammatory process, and are, therefore, indicative of renal 

 inflammation. Other evidences or symptoms should also be 

 taken into account. 



Occasional- 

 ly it is diffi- 

 cult to find 

 casts even 

 when they 

 are known to 

 exist. Alka- 

 line urine has 

 a tendency to 

 dissolve them 

 At times 

 they will not 

 settle for 

 hours. Usu- 

 ally if al- 

 lowed to 

 stand s i x 

 hours, the 

 casts will set- 

 -le if they are 

 present. The 



centrifuge will bring them down in a few minutes. A low power 

 of the microscope (150-200 diameters) may be used in the search 

 for casts and will enable the observer to pass over the field quite 

 rapidly. To identify the cast and its structure, a power of 400- 

 500 diameters is required. More than one specimen must always 

 be examined before giving a positive statement as to the presence 

 or absence of casts. False or pseudo-casts have been described; 

 these are believed to be accidental formations, while true casts in 

 general indicate nephritis. 



True casts may appear in three different sizes according to 

 the portion of the tubule in which they are formed. The smallest 

 size originates in the narrow tubule. The next in size comes from 

 the convoluted tubule of the second order (no casts from the 

 convoluted tubule of the first order, i. e., that portion of the 



Fig. 24. a. Blood cast and hyaline cast carrying 

 blood cells, b. Pus cast. c. Hyaline cast carrying epi- 

 thelial cells, d. Epithelial casts. (Greene). 



