The relation between amylase retention and excretion and non-protein nitrogen retention in experimental uranium nephritis / R. Fitz, M.D. Boston.

  • Fitz, Reginald, 1885-1953
Date:
1915
Catalogue details

Licence: In copyright

Credit: The relation between amylase retention and excretion and non-protein nitrogen retention in experimental uranium nephritis / R. Fitz, M.D. Boston. Source: Wellcome Collection.

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    Thus the amylase test is very similar to the phenolsulphone- phthalein test. It has certain disadvantages. In a series of nineteen rabbits, the normal excretion showed such marked variation that the information obtained from the test could only be applied to the indi¬ vidual case. Therefore in studying the renal function of any one it was first necessary to discover the normal excretion for that animal. It is only fair to state, however, that the results obtained in man by other observers tend to show that there is much less normal individual variation than in the experiments reported here. A second disad¬ vantage with the test is that it is less quantitative than the phenolsul- phonephthalein test. If the “absolute diastatic strength’’ is taken, small changes in the output of urine may exaggerate changes in renal func¬ tion. If the “d” reading is accepted, slight changes in renal function are overlooked. Possibly a different method of diluting the urine, as suggested by Brown and Smith,21 may obviate this source of error. On the whole, these experiments show that there is a close parallel¬ ism between the modes of excretion of phenolsulphonephthalein and amylase, and that amylase like phenolsulphonephthalein diminishes with an increasing nephritis, returns to normal with improvement of renal function, and is not influenced by blood retention to the same extent as is the accumulation of non-protein nitrogen. CONCLUSIONS 1. In acute uranium nephritis in rabbits, the excretion of amylase in the urine and the amount of non-protein nitrogen in the blood vary from the normal during the course of the nephritis and return to nor¬ mal as the nephritis heals. 2. In individual cases the degree of variation from the normal agrees on the whole with the amount of destruction demonstrated his¬ tologically in the kidney. • 3. The amylase excretion, like that of phenolsulphonephthalein, drops rapidly to its lowest point and returns rapidly toward its previous level with recovery of the kidney. It is but little influenced by accumu¬ lation in the blood. 4. The non-protein nitrogen accumulates gradually in the blood, and returns to normal gradually as the kidney recovers. 5. Amylase excretion as a test for renal function is similar to phenolsulphonephthalein, but is less delicate. 6. The amylase and phenolsulphonephthalein tests show the renal function at the moment; the blood nitrogen test is more influenced by the duration of the condition causing its accumulation. Peter Bent Brigham Hospital. 21. Brown and Smith: Bull. Johns Hopkins Hosp., 1914, xxv, 213.