Creatin and creatinin / by Edward Mellanby.

  • Mellanby, Edward, Sir, 1884-1955.
Date:
[1908?]
Catalogue details

Licence: In copyright

Credit: Creatin and creatinin / by Edward Mellanby. Source: Wellcome Collection.

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    cyamin feeding, obtained by these observers, may indicate that cieatin is normally formed by the methylation of glycocyamin. Recently, work has been done on the urinary creatinin by several workers, among whom may be mentioned Klercker*16) and Closson(7). Both these men confirm Folin’s conclusion that the endogenous creatinin elimination is constant despite varying nitrogenous intake of creatin-free food. Also that the quantity excreted appears to be quantitatively dependent on the body weight. Considering the amount of research being carried out on creatinin eliminated under various conditions of diet intake and energy output, it was thought well after having tested the colorimetric method of estimating creatin as creatinin, to go to the root of the matter like the earliest researchers and to experiment with the muscle direct. 2. Method of estimation. At the beginning of this research, the idea was to confirm Folin’s colorimetric method of estimation by isolating creatinin from urine and comparing the weight of the isolated substance with that calculated from the colorimetric reading. The necessity of this kind of confirmation was felt because of the belief that a colorimetric estimation of pure creatinin would be quite different from the result of an estimation of urinary creatinin. An endeavour was made to estimate creatinin in urine by the Neubauer(20) method. This consists of the addition of Ca(OH)2 to urine, evaporating the filtrate and making it up to an 80 per cent, alcoholic solution. To this solution alcoholic zinc chloride is added and the precipitated creatinin-zinc chloride compound is weighed. This method was quickly found to be impossible. The alcoholic solution after standing in a cold place for several days was generally found to contain a great deal of creatinin. In one case as much as *26 gr. of creatinin- zinc chloride was further precipitated from the filtrates after the appli¬ cation of the Neubauer method. Many other criticisms of this method of estimation might be made but as it now stands generally condemned, even if only because of the amount of controversy which it has brought about, it will be sufficient to say that I feel no confidence whatever in the results of all the older workers who used this method. As for those experimenters who deduced the quantitative relation of creatin to creatinin in muscle using this method of estimation, their results must be quite wrong. In the first place the solutions used are always made