184 CORTEX 



creased concentration of the erythrocytes in the peripheral 

 blood as contrasted with the venous blood such as occurs in 

 surgical or traumatic shock in which the loss of fluid presum- 

 ably occurs by leakage through the capillary endothelium. 



Before attempting to explain the changes in the water metab- 

 olism observed during adrenal insufficiency, it is necessary 

 to consider the changes in the concentration of the osmotically 

 active constituents (sodium, potassium, chloride, etc.) which 

 accompany the changes occurring in the water metabolism. 



SODIUM 



The inorganic constituents of the blood undergo marked 

 changes in their concentration during adrenal insufficiency. 

 These changes are most pronounced in the case of sodium, 

 chloride, and potassium, as shown in Figure 11, in which are 

 reproduced typical curves of the blood chemistry changes oc- 

 curring in the dog following adrenalectomy. The sodium con- 

 tent of the blood plasma is usually decreased about 15 per 

 cent below its normal level in experimental cortical insuf- 

 ficiency while the chloride content is diminished to a some- 

 what lesser extent. 



The drop in the sodium and chloride contents of the blood 

 in adrenal insufficiency is due to a loss of these substances in 

 the urine. During the early stages of adrenal insufficiency, as 

 Loeb, 398 Harrop, 265 and their coworkers have shown, there is 

 a negative balance of sodium and chloride due to an excre- 

 tion of these substances in the urine in an amount which ex- 

 ceeds their intake by the organism. 



As shown in Chapter XI, anatomical evidence indicates 

 injury of the renal tubules in adrenal insufficiency, and one 

 can adequately explain all the observed changes in the blood 

 chemistry which occur in adrenal insufficiency on the basis of 

 this tubular injury. According to our present theories of 

 renal function, the blood plasma is filtered through the glo- 

 meruli to give a protein-free ultrafiltrate in which the filterable 



