APPENDIX TO URINE. 



i. THE PIGMENTS. 



(1) The chief pigment of the urine is urochrome, which gives urine its 

 yellow colour. 



(2) Urobilin is present only in small quantities, generally in the form of its 

 chromogen, urobilinogen. Under certain pathological conditions its amount 

 may be greatly increased. Urobilin is derived from haematin and is very like 

 hydrobilirubin, which is obtained by reduction of bilirubin. It is identical 

 with stercobilin, the yellow pigment of the faeces. 



(3) Uroerythrin gives the pink colour to urate sediments. Normally it is 

 present only in small amounts, but is greatly increased in' certain diseases. 



(4) Hsematoporphyrin is also only present in small amounts. 



I. Urochrome and Urobilin in Normal Urine. 



Normal urine shows no absorption bands with the spectroscope but only a 

 general absorption of the violet. Neither urochrome nor urobilinogen show 

 absorption bands. 



Urine is saturated with ammonium sulphate crystals 1 and allowed to 

 stand a short time. The precipitate, which consists of ammonium urate as- 

 sociated with the chromogen of urobilin, is filtered off and extracted with 

 hot alcohol. The alcoholic solution shows no absorption band or only a 

 very faint one ; on acidifying it, the chromogen is broken up and the absorp- 

 tion band of urobilin can be seen at the junction of the green and blue. 



To the filtrate containing the ammonium sulphate is added 2-3 times 

 its volume of alcohol. The ammonium sulphate is precipitated and a clear 

 yellow layer of alcohol containing the urochome forms above the salt solution. 

 It shows no absorption bands on examination with the spectroscope. 



II. Pathological Urine Containing Excess of Urobilin (or 



Normal Urine). 



The urates are precipitated by saturating the urine with ammonium 

 -chloride 2 and filtered off. The filtrate is saturated with ammonium sulphate, 

 acidified with a drop of sulphuric acid and shaken up with a mixture of 2 

 parts of ether and i part of chloroform. The urobilin is taken up by this 

 solvent and shows the absorption band well. If the ether-chloroform layer 

 be pipetted into another test tube and shaken well with water made slightly 

 alkaline with caustic soda, the pigment passes entirely into the alkaline solu- 

 tion. A solution of urobilin in alcohol shows a green fluorescence and an 

 -absorption band in the green between b and F. 



III. Pathological Urine Containing a Pink Urate Sediment, 

 Uroerythrin. 



The urate sediment is filtered off. If to a portion of this precipitate 

 caustic soda be added, the pink colour becomes green. If the remainder of 

 the precipitate be dissolved in hot water and the solution extracted with 

 acetic ester or amyl alcohol, a pink solution is obtained which shows two 

 absorption bands in the green ; ir weak, only one. 



IV. Haematoporphyrin in Normal Urine. 



For the detection of haematoporphyrin in normal urine, in which it is present 

 -as alkaline haematoporphyrin, at least 200-400 c.c. are necessary, but in patho- 

 logical urine, where its quantity is increased, a smaller quantity can be used. 

 The best method is that of Garrod. To every 100 c.c. of urine are added 20 

 c.c, of dilute caustic soda. This precipitates the earthy phosphates which carry 

 down the pigment. The urine must give a precipitate like that of normal urine, 

 otherwise calcium phosphate in acetic acid solution must be added before 

 precipitating. This is obtained by precipitating a little calcium chloride with 

 sodium phosphate in a test tube. Too large a precipitate should be avoided. 

 The earthy phosphates are allowed to settle and the supernatant liquid is 

 poured off; they are transferred to a filter paper and washed with water (till the 

 washings are colourless if haematoporphyrin free from other pigments be re- 

 quired ; too much washing must be avoided if only a little haematoporphyrin be 

 present). The precipitate is extracted with alcohol, acidified with hydiochloric 

 -acid and the solution is examined for the spectrum of acid haematoporphyrin. 



1 80 gm. per too c.c. 2 27 gm. per 100 c.c. 



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