478 G ASTRO-INTESTINAL "AUTOINTOXICATION 



CYSTIN AND CYSTINURIA 1 



The presence of cystin in the urine has been observed in a 

 number of cases, and when present at all it is usually present 

 in considerable quantities. Because of its slight solubility it 

 appears as a deposit of hexagonal crystals, and frequently 

 forms cystin concretions (g. v.) in the urinary bladder. 2 

 Baumann and others observed that in cystinuria the urine 

 often contains, besides the cystin, the diamins cadaverin and 

 putrescin, which are both formed in the intestines through 

 putrefaction, and they naturally suspected that cystin arose in the 

 same way. Another view was that the diamins interfered 

 with the oxidation of sulphur in the body, so that it was 

 eliminated in the unoxidized form of cystin. But it has been 

 demonstrated that neither of these hypotheses is correct, for (1) 

 cystin could not be found in the feces ; (2) if given by mouth, it 

 is completely oxidized, and causes only the appearance of 

 excessive amounts of sulphates in the urine; (3) cystinuria 

 has been observed to occur independent of the presence of 

 the diamins, 3 and not to be modified or caused by their adminis- 

 tration or pathological formation. The view now prevalent 

 is that the cystin that escapes in the urine in cystinuria is not 

 derived from intestinal putrefaction, but is formed in the tissues 

 from the proteid molecule, and fails to be further decomposed 

 because of some anomaly of metabolism. This view is sup- 

 ported by the fact that cystinuria often appears to be an hered- 

 itary disease, occurring in families for several generations ; it 

 is independent of the diet, cystin appearing even if proteids are 

 withheld, and also independent of intestinal putrefaction. It 

 having been found that leucin and tyrosin may also occur in the 

 urine in cystinuria, 4 it seems probable that this condition 

 depends upon a general abnormality of proteid metabolism. 5 



1 Literature concerning cystin given by Friedmann, Ergebnisse der Physiol., 

 1902 (I, Abt. 1), 15 ; and by Mann, Chemistry of the Proteids, pp. 56-64. Cys- 

 tinuria reviewed by Bodtker, Zeit. physiol. Chem., 1905 (45), 393. 



2 Abderhalden (Zeit. physiol. Chem., 1903 (38), 557) has described a case 

 in a child in which the organs were infiltrated with masses of the cystin crys- 

 tals. 



3 See Garrod and Hartley, Jour, of Physiol., 1906 (34), 217. 



4 Abderhalden and Schittenhelm, Zeit. physiol. Chem., 1905 (45), 468. 



5 The question as to the identity of proteid cystin and " stone cystin" raised 

 by Loewi and Neuberg seems to have been decided affirmatively. As to the 

 condition of general proteid metabolism in cystinuria, the discussion is at the 

 present time too unsettled to permit of consideration. For discussion and 

 literature see Alsberg and Folin, Amer. Jour. Physiol., 1905 (14), 54; also 

 Marriott and Wolf, Amer. Jour. Med. Sci., 1906 (131), 197 ; Garrod and Hart- 

 ley, lac. tit. 



