Diseases of the kidneys and of the spleen : hemorrhagic diseases / by Dr. H. Senator and Dr. M. Litten ; edited with additions by James B. Herrick ; authorized translation from the German, under the editorial supervision of Alfred Stengel.

  • Senator, H. (Hermann), 1834-1911.
Date:
1905
Catalogue details

Licence: Public Domain Mark

Credit: Diseases of the kidneys and of the spleen : hemorrhagic diseases / by Dr. H. Senator and Dr. M. Litten ; edited with additions by James B. Herrick ; authorized translation from the German, under the editorial supervision of Alfred Stengel. Source: Wellcome Collection.

    30/858 (page 26)
    Tests for Albumin.—In order to demonstrate the presence of any form of albumin, the urine must be perfectly clear. Turbid urine must therefore be filtered before an analysis is made, and, if necessary —that is, if simple filtering does not clear it up sufficiently—must be shaken up with a little burnt magnesia. If the urine is very concen¬ trated, it is advisable, in order to obtain more trustworthy results, to dilute it with water. The oldest method, the one by which Cotugno discovered albumin in the urine, consists in boiling the urine, which must be acid in reaction. It is not very reliable, because it produces turbidities that are not due to the presence of albumin, and if the quantity of albumin is very small the test is not to be depended upon. If a little nitric acid is added to the boiled urine the test is somewhat more reliable, as the nitric acid clears up the other turbidities which are due to earthy salts; but small quantities of albumin may escape detection because they are destroyed by boiling with nitric acid, and the albumoses are altogether overlooked because they remain in solution at high temperatures. The writer recommends the following methods as trustworthy and at the same time sufficiently sensitive in every instance for the require¬ ments of general practice. 1. Nitric Acid Test.—While the urine is cold, pure (officinal) nitric acid is added—best by means of a pipet—by carefully allowing it to flow down along the side of the test tube held at an angle, so that the acid, which is heavier than the urine, collects at the bottom of the tube, where it forms a plainly visible layer, £ to 1 cm. (about \ in.), in thickness. In the presence of albumin or albumoses a white precipitate of varying thickness is formed at the plane of contact of the two fluids and spreads upward; if the quantity of albumin is very small, the cloud forms only after one or two minutes. When the urine contains a great deal of pigment a brown or violet pigmentation may appear between the urine and the layer of albumin; but this does not interfere with the recognition of the albu¬ minous cloud. When the urine is very concentrated the addition of nitric acid not infrequently produces a cloud, which is due to urates, and which might pos¬ sibly be mistaken for albumin. If, however, the nitric acid is added exactly as the writer has indicated above, the turbidity due to urates, which is delicate like a veil and may appear crystalline to the naked eye, spreads from above downward and disappears when the urine is slightly warmed; these two points serve to dis¬ tinguish it from the turbidity due to albumin. In doubtful cases the test may be repeated after diluting the urine, as the urates then remain in solution. Finally a cloud may appear on the addition of nitric acid when the urine contains certain excretory products which occur after the ingestion of resins or balsamics; but these substances are dissolved by alcohol or ether. If by this test a precipitate is formed that is not due to uric acid or acids derived from resins, it may indicate ordinary albumin (serin and globulin) or albu¬ moses or both. If the precipitate disappears on the application of heat, it is composed of albumoses. It is advisable to take another specimen of urine and repeat the test in the inverse order—that is, the urine, which must be acid in reaction, is first boiled and then treated with nitric acid—by this procedure a cloud due to phosphates is dissolved while the albumin remains undissolved. If the precipitate should first form after the urine cools, it would indicate the presence of albumoses. When the urine contains a very minute quantity of albumin a precipitate is sometimes formed on boiling, which disappears wholly or in part after the addi¬ tion of nitric acid. In this case a greater part of the precipitate is due to phos¬ phates, and the quantity of albumin is so small that it is recognized only after the urine has completely cooled and the albumin has settled to the bottom of the test tube.