476 



UREA. 



as well as with the degree of disintegration of the nitrogen-containing 

 tissues in the body. As the latter is increased by withholding oxygen 

 and by hemorrhage, these also cause an increase in the amount of urea. 

 The administration of large amounts of water by more thorough 

 washing out of the tissues and also of salts, frequent micturition and 

 exposure to compressed air likewise increase the amount of urea. In 

 diabetics who partake of large amounts of food, the amount of urea 

 occasionally exceeds 100 grams daily, while in the state of hunger it 

 falls to 5.6 grams. In the state of inanition a maximum of elimination 

 has been observed toward noon, and a minimum toward morning. 



Daily variations in the amount of urea pursue a course parallel with 

 the amount of urine. Three or four hours after digestion begins the forma- 

 tion of urea reaches its maximum, subsequently falling again and reaching 

 its minimum during the night. The excretion of urea, and in the same 

 proportion that of the total nitrogen, with the urine is materially aug- 

 mented in consequence of increased muscular activity. This excretion 



FIG. 146. i, 2, Prisms of pure urea; 3, rhombic plates; 4, hexagonal tablets; 5, 6, irregular scales and plates 



of urea nitrate. 



is less on the first working day, as observed in dogs, than on the second 

 and third, but it is still increased on the two resting days succeeding 

 the work. 



Pathological. In the presence of acute febrile inflammatory processes and of 

 fever in general, the excretion of urea increases to the height of the morbid process, 

 in association with which it again declines. After the cessation of the process 

 the excretion is often subnormal. At times the formation of urea may be in- 

 creased in association with high fever, but the excretion may be checked and 

 retention of urea takes place. In the further course of the disorder the excretion 

 may be greatly increased. In chronic diseases the amount of urea varies with 

 the state of the nutrition, the metabolism of the patient and in accordance with 

 the height of the accompanying fever. Degenerative disorders of the liver, as, 

 for instance, from phosphorus-poisoning, may be attended with diminished excre- 

 tion of urea and increased excretion of ammonia. 



Substances that increase the proteid disintegration in the body, as, for instance, 

 arsenic, antimony-combinations, and small amounts of phosphorus, increase the 

 formation of urea; while those that conserve proteids, as, for instance, quinin, 

 diminish the production. Increased formation of bile in the liver gives rise at the 

 same time to increased formation of urea. 



