Anatomical Changes, Symptoms. 985 



in peritonitis and in edema of the thoracic organs, finally in 

 exceptional cases, owing to compression or thrombosis of the 

 posterior vena cava. 



Anatomical Changes. The arterial hyperemia is manifested 

 by livid redness of the renal substance, in which the congested 

 glomeruli often stand out sharply and appear as dark red spots 

 on the cut surface of the cortical substance. 



In venous hyperemia the kidneys are dark blue-red, some- 

 what enlarged and firm ; the tense capsule is easily peeled off, 

 whereupon the smooth surface of the cortical layer, which is 

 traversed by venous plexuses (Stellulae Verheyenii) becomes 

 visible. A somewhat prolonged blood stasis leads gradually to 

 an increase of connective tissue which causes the kidneys to be- 

 come very firm (Induratio cyanotica renum), but later their vol- 

 ume diminishes with the atrophy of the newly formed connective 

 tissue, the surface becomes irregular, and the renal capsule 

 adheres in places to the substance of the kidneys (Atrophia 

 cyanotica). In stasis-hyperemia there is no cellular infiltration 

 in contrast to inflammatory atrophy of the kidneys, but red 

 blood corpuscles lie in small clumps between the tortuous 

 urinary tubuli (Kitt). 



Symptoms. In arterial hyperemia of the kidneys an in- 

 creased amount of arterial blood flows in a given time through 

 the kidneys, in consequence the quantity of urine increases 

 and its specific gravity becomes lower. Aside from polyuria 

 (see p. 918), which is usually accompanied by an increased 

 sensation of thirst, a certain sensitiveness in the region of 

 the kidneys and a stiff gait were noted in many cases. 



In venous hyperemia of the kidneys the slowing of the 

 blood stream results, as an immediate consequence, in a 

 diminution of the quantity of urine. If the stasis of the blood 

 is prolonged, the nutrition of the epithelial cells suffers and 

 there occurs an albuminuria which is usually only slight; on 

 microscopical examination red blood corpuscles and hyaline 

 casts may sometimes be found in the urine. The specific 

 gravit}^ of the latter is increased and it contains, in carnivora, 

 large quantities of acid urates which form, on cooling, a reddish 

 sediment on the bottom of the vessel and disappear when the 

 urine is heated. 



Diagnosis. For the determination of arterial renal 

 hyperemia it is necessary to exclude all other diseases for 

 which polyuria is also characteristic. — Diabetes mellitus is 

 distinguished by its high specific gravity and the content in 

 grape sugar, chronic indurative nephritis differs by the amount 

 of albumen present in the urine and by the long duration of 

 the disease. — From diabetes insipidus arterial hyperemia can 



