METABOLISM IN NEPHRITIS 351 



locally, and is excreted practically entirely by the kidneys and with ex- 

 traordinary rapidity, appearing in the urine normally within a few min- 

 utes of injection. In alkaline solution it presents a brilliant red color 

 which is ideally adapted for quantitative colorimetric estimation." (Rown- 

 tree and Geraghty. ) 



Technic. About one-half hour before the drug is injected 400 c.c. 

 of water are given. One c.c. of a specially prepared solution containing 

 6 mg. of phenolsulphonephthalein are injected intramuscularly, prefer- 

 ably in the lumbar muscles. At the end of two hours and ten minutes (ten 

 minutes to allow for absorption and two hours for excretion) the urine is 

 collected. It is made decidedly alkaline with a sodium hydroxid solution 

 (10 to 25 per cent) diluted to one liter and the percentage of phthalein 

 excreted is determined by comparison with the standard in a suitable 

 colorimeter. There are many variations from this technic (Rowntree and 

 Geraghty) which may be employed according to various indications or 

 opinions. 



In the author's experience subcutaneous injections have been ex- 

 tremely unsatisfactory and intravenous injections have occasionally pro- 

 duced undesirable reactions. Keith and Thomson noted reappearance of 

 hematuria in acute nephritis following the injection of phthalein. Such 

 untoward experiences are rare and should not act as a deterrent to an em- 

 ployment of the test. In pregnancy the phthalein injection is not fol- 

 lowed by an excretion as in other individuals; under these circumstances, 

 therefore, it is of no value. Kendall finds that the tissues have the power 

 to destroy phthalein; this may interfere with the test theoretically and 

 may account for occasional bizarre findings, but certainly does not serve 

 to annul the worth of a most useful procedure. 



Some inaccuracies that occur may be due to the fact that the solution 

 of the dye for injection is not of the proper strength, either because it has 

 been carelessly compounded or because it has deteriorated. If precautions 

 are taken to have the standard and injected material of the same propor- 

 tionate value many of the apparent discrepancies will be obviated. 



The normal excretion of phthalein is 60 per cent or more in two hours 

 (Rowntree and Fitz) .though in many instances the lower normal limit 

 appears to be 50 per cent. In children the usual output is somewhat higher, 

 76 to 81 per cent (Tileston and Comfort(6) ; Hill). 



Clinical Significance. The first question to be dealt with under this 

 heading is, What does a diminished excretion of phthalein signify ? To 

 answer that it indicates a subnormal renal function is not entirely satis- 

 factory to-day. In addition, the problem of which anatomical portion 

 of the kidney tubules, glomeruli or blood vessels is involved, or of which 

 excretory product water, salt, urea, etc. parallels phthalein elimina- 

 tion has to be met. "Experimental evidence seems to indicate that phenol- 

 sulphonephthalein is excreted mostly by the tubules, but also to a slight 



