DIAGNOSTIC REAGENTS 329 



or the amount excreted is below normal, an impairment of renal function is indi- 

 cated. The degree of dysfunction may be estimated by the proportionate amount 

 excreted. The functional efficiency of each kidney may be determined by cathe- 

 terizing each ureter and collecting the excretions separately. 



For the performance of the test, exactly 1 ml. of the solution containing 6 mg. 

 of phenolsulfonphthalein is carefully withdrawn from a Phenolsulfonphthalein 

 Ampul, Difco, by means of an accurately graduated syringe. This solution is in- 

 jected either intramuscularly or intravenously, aseptic technique being observed 

 throughout. {Note: More than 1 ml. has been placed in each ampul in order that 

 exactly 1 ml. may be easily withdrawn) . To insure copious excretion of urine, the 

 patient is given 200-400 ml. of water 20-30 minutes before the beginning of the 

 test. If this precaution is not taken, a late appearance of phenolsulfonphthalein 

 in the urine may be due to lack of excretion. The patient's bladder must be 

 emptied, preferably by catherization, the time noted, and 1 ml. of phenolsul- 

 fonphthalein solution injected. When the injection is made intramuscularly, the 

 most suitable site is in the lumbar region. The area surrounding the point of in- 

 jection must be free from edema. If the patient is catheterized the urine may be 

 allowed to drain into a test tube containing a drop of 25 per cent sodium hydrox- 

 ide solution and the time noted for the appearance of phenolsulfonphthalein 

 denoted by the first faintly pink tinge. In patients having no obstruction to the 

 free passage of urine, the catheter may now be withdrawn. If there is no urinary 

 obstruction and the passing of the catheter be disagreeable or inconvenient, it 

 may be omitted, in which case the first appearance of the dye in the urine is not 

 noted. When the phenolsulfonphthalein is administered intramuscularly, the 

 patient is instructed to void into a suitable receptacle at the end of 70 minutes 

 and again into another receptacle at the end of the second hour. If the injection 

 is made intravenously, it is customary for the urine to be collected at the end of 

 15 minutes, 30 minutes or 1 hour. 



The amount of phenolsulfonphthalein in the urine may be estimated by making 

 the sample alkaline with a sufficient quantity of 25 per cent sodium hydroxide 

 solution, diluting to 1 liter, and after filtering, if necessary, comparing the depth 

 of color with that of a standard solution. When the color is faint, it is advisable 

 to dilute to only 500 ml., in which case the result should be divided by 2. 



If the comparison is made by means of the ordinary biological colorimeter, it 

 is customary to use a 50 per cent standard, prepared by diluting 0.5 ml. of the 

 same solution used for injection, to 1 liter, after the addition of a few drops of 

 25 per cent sodium hydroxide solution to insure the development of the full 

 alkaline color. If this standard solution is kept in a cool place and not exposed 

 to strong light, it will keep for several months. 



The depth of color may be also conveniently, but less accurately, estimated by 

 placing a small quantity of the diluted alkaline sample in a tube or vial and com- 

 paring the depth of color with similar tubes or vials containing amounts of alka- 

 line phenolsulfonphthalein corresponding to 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 

 60, 80 and 100 per cent. The 100 per cent standard is prepared by diluting 1 ml. 

 of solution from a Phenolsulfonphthalein Ampul, Difco, and a few drops of 25 

 per cent sodium hydroxide solution to 1 liter. The other standards are made by 

 appropriate dilution of the 100 per cent standard. 



Complete details of the phenolsulfonphthalein renal function test will be found 

 in the references of the original articles as given below and also in such texts as 

 "Manual of Clinical Laboratory Methods" by Cummer, "Diagnostic Methods" 

 by Webster, "Approved Laboratory Technic" by Kolmer, Spaulding and Robin- 

 son and other similar texts. 



=}: 



Pharmacol ., 1:231:1909. 

 Phsurmacol., i: 579:1910. 



