422 PHYSIOLOGICAL CHEMISTRY 



PROTEINS 



Normal urine contains a trace of protein material, but the amount 

 present is so slight as to escape detection by any of the simple tests in 

 general use for the detection of protein urinary constituents. The 

 following are the more important forms of protein material which have 

 been detected in the urine under pathological conditions: 



(1) Serum albumin. 



(2) Serum globulin. 



Deutero-proteose. 



(3) Proteoses Hetero-proteose. 



"Bence- Jones' protein." 



(4) Peptone. 



(5) Nucleoprotein. 



(6) Fibrin. 



(7) Oxyhemoglobin. 



ALBUMIN 



Normal urine contains a trace of albumin which is too slight to be 

 detected by the* usual procedures. 



Albuminuria is a condition in which serum albumin or serum globulin 

 appears in the urine. There are two distinct forms of albuminuria, i.e., 

 renal' albuminuria and accidental albuminuria. Sometimes the terms 

 "true" albuminuria and "false" albuminuria are substituted for those 

 just given. In the renal type the albumin is excreted by the kidneys. 

 This is the more serious form of the malady and at the same time is more 

 frequently encountered than the accidental type. Among the causes of 

 renal albuminuria are altered blood pressure in the kidneys, altered 

 kidney structure, or changes in the composition of the blood entering 

 the kidneys, thus allowing the albumin to diffuse more readily. In the 

 accidental form of albuminuria the albumin is not excreted by the 

 kidneys as is the case in the renal form of the disorder, but arises from 

 the blood, lymph, or some albumin- containing exudate coming into 

 contact with the urine at some point below the kidneys. It has been 

 suggested 1 that albuminurias may be classed as pre-renal, renal and 

 post-renal. The pre-renal type is illustrated by the albuminuria of 

 heart disease, whereas the post-renal form corresponds to what we have 

 called "accidental" albuminuria. 



The determination of albumin may be of assistance in following the 

 course of kidney disturbances, but the results can only be interpreted 

 in the light of other clinical findings. 



1 Bruce: Lancet, May 6, 1911, p. 1205. 



