402 AMBARD 's INDEX OF UREA EXCRETION 



often noted that the albumin content of the urine of pyelitis is far greater than that 

 from cystitis. This is true for pyelonephritis but does not hold for simple pyelitis. 



Pyelitis, usually a colon infection, must always be thought of in 

 vague disorders of children and pregnant women. 



Renal stone and renal tuberculosis often give similar symptoms but the X-ray 

 and animal inoculation test should differentiate. 



DETERMINATION OF EFFICIENCY OF RENAL FUNCTIONING 



At present we are paying great attention to laboratory tests which 

 give us an idea of the activity of nitrogen metabolism and efficiency 

 of the renal functions. Probably the most reliable single test is the 

 phenolsulphonephthalein or "red" test. This is given in the appendix. 

 For alveolar CO 2 content see Acidosis. 



Determination of the ammonia output in the urine is also of value in conditions 

 of acidosis. In acidosis connected with diabetes we expect a great increase in the 

 urinary ammonia to neutralize acetone bodies as is also true of degenerations invol- 

 ving the parenchymatous liver cells, when the urea function is interfered with. 

 In the acidosis of chronic nephritis, however, we may have a deficiency in the ammo- 

 nia output in the urine. Simple tests for this determination will be found in the 

 appendix. 



Great attention is being given to the nonprotein nitrogen of the blood as well 

 as to blood urea. See appendix. 



The study of nitrogen metabolism is best undertaken with a patient 

 on a known nitrogen value diet and the most accurate determination 

 is along the lines of the Ambard index of urea excretion. 



Ambard Index. McLean has worked out an index of urea excretion based on 

 the Ambard variables of (i) concentration of urea in the blood. (2) Concentration 

 of urea in the urine. (3) Rate of urinary excretion and (4) weight of the individual. 

 McLean's formula is as follows: 



_ . 



= Index of urea excretion. 



D = Grams urea excreted in twenty-four hours. 



C = Grams urea per liter urine. 

 Ur = Grams urea per liter blood. 

 Wt = Eody weight, individual in kilograms. 



One hundred is accepted as a typical normal finding, and findings down to 80 

 as within normal limits. In deficiency of renal function the index falls below 50 

 and in cases of marked deficiency may fall below 10, and in terminal stages 

 index may approximate i. Such cases practically show an absence or only a trace 

 phenolsulphonephthalein excretion. 



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