618 



THE UBINARY ORGANS. 



kidney. Thrombosis of the renal vein may be induced by the pressure 

 of tumors, either on this vessel or on the vena cava ; or it may occur in 

 cachectic conditions. 



ALBUMINUBIA AND CASTS. 



Albuminuria. Albuminous material or serum not infrequently passes 

 out of the blood-vessels of the kidneys, either through the glomeruli or 

 the tubules, and mingles with the excreted substances. While this may 

 occasionally occur under conditions which cannot be regarded as ab- 

 normal, it is common in many diseases of the kidney and is frequent 

 without demonstrable kidney lesions in fevers, infectious diseases, ab- 

 normal conditions of the blood, various forms of poisoning, disturbances 

 of the circulation, etc. Albuminous material may also be set free by 

 abnormal metabolism or disintegration of the renal epithelium. 



In albuminuria with pronounced kidney lesions there are usually 

 well-defined alterations in the capillaries of the tufts and in their epi- 

 thelial investment. There may be thrombi in the capillaries ; their walls 

 may be thickened ; the flat epithelium covering them may be swollen or 

 fatty, or may peel off, or it may proliferate. In the kidneys of cases of 

 pronounced albuminuria, preserved in alcohol or other fixatives which 

 coagulate albuminous material, this substance may be seen within Bow- 

 man's capsule or in the lumina of the tubules as fine or coarse granules. 



FIG. 378. HYALINE GLOBULES IN URINIFEROUS TUBULE. 

 There Is also degeneration and disintegration of the epithelium. 



Albuminous material in the tubules may form casts (see below) or when 

 the conditions are favorable fibrillar fibrin may form. 



Casts. Albuminous material which under various abnormal condi- 

 tions has escaped from the blood-vessels in solution may coagulate, 

 especially in the lumina of the tubules, forming the more or less cylin- 

 drical or globular structures called casts. These may be homogeneous 

 in structure hyaline casts ; or the albuminous material of which they 



