540 ABNORMALITIES IN METABOLISM 



which appeared only when the urea concentration of the blood had 

 reached levels of 160 to 245 mg. of urea per 100 c.c. i. e., just the con- 

 centrations that are usually seen in well developed uremia. If in these 

 experiments of brief duration such marked symptoms were produced 

 by urea, what striking effects must be expected when these same urea 

 concentrations are continued in the blood for days and weeks at a 

 time.^^ We must find out what results not only from urea, but from 

 creatinine and uric acid kept in the blood at the concentration found 

 in uremia for long periods, as well as any other substance that may be 

 increased in the blood in uremia. An experiment of a few minutes' 

 or hours' duration cannot be expected to duplicate or elucidate a con- 

 dition of weeks duration. In chronic diseases our experimental in- 

 vestigations must be of some reasonably comparable duration, and this 

 principle of investigation is now made possible by Woodyatt's methods. 

 And finally, in view of the extremely varied symptomatologj^ of renal 

 incompetence, we must recognize that it is highly probable that in 

 different cases these symptoms vary because of different conditions. 

 In one case, urea may be the chief factor, in another the action of urea 

 may be complicated by the effects of acidosis or high blood pressure 

 per se, while in others cerebral edema may be the chief influence. 

 Some continental writers hold that there is a true uremic picture due 

 solely to cerebral edema from salt and water retention, occurring 

 especially in the young, to be distinguished from the uremia of nitro- 

 genous retention, and from a pseudouremia resulting from the circula- 

 tory disturbances of arteriosclerosis. ^° Rowland and Marriott caU 

 attention to the reduced calcium in the blood in uremic acidosis, and 

 as nervous irritability is increased by reduction of calcimn this may also 

 be a factor in the nervous manifestations of uremia. All possible 

 shades of cooperating influences may be expected to occur when the 

 kidneys fail, and to explain the confused, variable, changing picture 

 of the uremic state. ^^ 



TOXEMIAS OF PREGNANCY" 



Under this heading are included eclampsia, as characterized by 

 convulsions and certain anatomical changes, together with those in- 

 stances of intoxication with similar anatomical changes and no con- 



*^ However, in Salachians the normal urea content in the blood is over two 



per cent, and ammonium salts exceed ^^ NHs, (See A. B. Macallum, Amer. Jour. 



Med. Sci., 1918 (156), 1), but it may well be that in such species the tissues are 

 adapted to their environment. 



60 See Haim and TchertkofT, Rev. M6d. Suisse Romande, 1918 (38), 15. 



"^ The influence of a hypothetical internal secretion of the kidney (Brown- 

 Sequard)), or of the products of nephrolysis (.Ascoli), as a cause of uremia, may now 

 be considered as of historical interest only. (See Pearce, Arch. Int. Med., 1908 

 (2), 77; 1910 (5), 133.) The same is true of the attempt to explain the high 

 blood pressure as the result of adrenal hypertrophy. (Pearce, Jour. Exp. Med., 

 190S (10), 735; 1910 (12), 128.) 



" Review and bibliography by Ewing, Amer. Jour. Med. Sci., 1910 (139), 829. 



