FATIGUE 459 



Mauban l distinguishes the following groups of conditions 

 causing acetonuria : Physiological acetonuria, diabetes, febrile 

 diseases, carcinoma, resorption of tissues and exudates, gastro- 

 enteritis, nervous diseases, general anesthesia, and inanition. 



As mentioned in discussing these diseases, lactic acid has 

 been found in the urine in osteomalacia and in rickets, but the 

 attempts to explain these diseases as due to solution of the bone 

 salts by the organic acids have not met with success. (See " Cal- 

 cification/' Chap. xv). In rheumatism lactic acid is said to have 

 been found in the urine and sweat, but these results have not 

 been verified, particularly as to the sweat, and the once promi- 

 nent idea that rheumatism is due to an acid intoxication seems 

 to have been given up. 2 In rheumatoid arthritis, as shown by 

 Herter and by Baldwin, 3 there is an excessive elimination of or- 

 ganic acids of undetermined nature in the urine. 



FATIGUE 



The symptoms of fatigue, whether general or local, seem to be 

 due to an intoxication with the products of the excessive meta- 

 bolic activity, and part of the symptoms, at least, seem to be due 

 to acid intoxication. Among the metabolic products of muscular 

 activity are known to be creatin, creatinin, sarcolactic acid, and 

 carbon dioxide. The amount of acid developed in an active 

 muscle is quite considerable, and when the activity is violent or 

 prolonged the sarcolactic acid accumulates, being formed faster 

 than it can be removed. Part of the acidity of the muscle is due, 

 however, not to the sarcolactic acid itself, but to monopotassium 

 phosphate (KH 2 PO 4 ), which is formed by the action of the 

 sarcolactic acid upon the dipotassium phosphate present in the 

 blood and muscle. The effect of these various substances upon 

 muscular fatigue has been studied experimentally, and while the 

 creatin seems not to be a " fatigue substance," sarcolactic acid, 

 monopotassium phosphate, potassium sarcolactate, and carbon 

 dioxide all cause muscle tissue to react to stimuli in the same 

 way that a fatigued muscle does (Lee 4 ). 



It is quite probable that the muscular weakness of diabetics, 

 and the exhaustion associated with many conditions in which 

 organic acids appear in the urine in abnormal quantities, depend, 



1 These de Paris, 1905. 



2 See Garrod, Treatise on Rheumatism, 1890. Walker and Ryffel (Brit. 

 Med. Jour., 1903 (ii), 659, report finding formic acid in the urine in acute 

 rheumatism. 



3 Amer. Jour. Med. Sci., 1904 (128), 1038. 



4 Jour. Amer. Med. Assoc., 1906 (46), 1491 ; where is given a complete re- 

 view of the subject of fatigue, with the literature. 



