CH. xxxix.] METABOLISM IN DISEASE. 59 1 



Exchange of Material in Diseases. 



Fever. Fever is a condition in which the temperature of the 

 body is raised above the normal, and the degree to which it is 

 raised is a measure of the intensity of the febrile condition. A 

 rise of temperature may be produced either by increased produc- 

 tion of heat, due to the increase of katabolic processes in the 

 body, or to a diminished loss of heat from the body. A mere 

 increase in the production of heat does not necessarily produce 

 fever. By administering an excess of food, combustion is increased 

 in the body ; but in the healthy individual this does not produce 

 a rise of temperature, because part passu with the increased pro- 

 duction, there is increased loss of heat. Similarly, diminution in 

 the loss of heat, such as occurs on a hot as compared with a cold 

 day, does not produce fever,* because the production of heat 

 within the body is correspondingly diminished. In fever there is 

 increased production of heat, as is seen by the study of exchange 

 of material ; the intake of food is, as a rule, very small ; the 

 discharge of nitrogen and carbon results from the disintegration 

 of tissues, which, as compared with that in simple inanition, is 

 large ; the tissues are said to be in a labile condition, that is, 

 they are easily broken down. In most febrile states, the skin is 

 dry, the sweat-glands, like most of the secreting organs of the 

 body, being comparatively inactive, and so the discharge of heat 

 is lessened. The skin may, however, sometimes be bathed in 

 perspiration, and yet high fever be present. The essential cause 

 of the high temperature is neither increased formation nor 

 diminished discharge of heat, but an interference with the reflex 

 mechanism, which in health operates so as to equalise the two. 



Increased nitrogenous metabolism in fever has been observed 

 in pneumonia, in pyaemia and in other febrile conditions. Ringer 

 showed the correspondence in temperature and output of nitrogen 

 very clearly in intermittent fever (ague). 



What is known as the epicritical increase of urea is the greatly 

 increased secretion of urea that occurs at the commencement 

 of the defervescence of a fever. It is probably not due to an 

 increased formation of urea, but to the removal of urea which has 

 accumulated, owing to the fact that the kidneys have been acting 

 sluggishly during the height of the fever. 



* A febrile condition does occur on undue exposure to a tropical sun, for 

 :M-I;IIICC in soldiers in India ; this is mainly due to their tight fitting and 

 otherwise unsuitable clothing, which interferes with the proper action of 

 the skin. 



