BIO-CHEMICAL NOTES BY GEOFFREY EVANS and H. E. ARCHER.

Renal Function.-Renal efficiency is a matter of importance in many surgical conditions, and particularly in operations for removal of the prostate. The estimation of the blood urea and the urea concentration test are both commonly employed to determine the state of the kidney function.

Both these tests are valuable up to a point, but they may both lose some of their value by the conditions under which they are performed. If a patient has been kept on a low protein diet for some time, a moderate degree of failure to excrete urea will not be revealed by a single estimation of the blood urea, because so little urea is in the blood stream that even inefficient kidneys are capable of dealing with it, and accumulation is unlikely. The urea concentration test may be considerably modified bg the taking of large quantities of fluid prior to the test, and in many cases complete emptying of the bladder a t hourly intervals is difficult. It is not easy in urgent cases to adjust these conditions, and for this reason a combination of the two tests is of much more value in assessing rend efficiency.

If, during the course of a urea concentration test, the blood urea be examined a t intervals of thirty minutes, it is found that in normal in- dividuals there is an early rise followed by a fall to within 10 to 15 milli- grams of the original level in five to six hours. As i t is often inconvenient to make a series of blood examinations, the following procedure is found to give all the necessary information.

The test is commenced in the early morning after the night fast, by first emptying the bladder as far as possible, and then taking a sample of blood for estimation of the blood urea. Fifteen grams of urea are then given, and the hourly specimens of urine collected in the usual way for three hours, their volume noted and their urea content estimated. Fivc hours later a second blood urea estimation is carried out, and its figure compared with that of the previous estimation. A patient with normal urea excretion will have low blood urea figures in both cases, and the second figure wiII be not more than 15 milligrams higher than the first. There will be a normal urea concentration test. A case of gross renal inefficiency will be shown by a high resting blood urea, and further test- ing is unnecessary. Moderate degrees of inefficiency will show a normal or slightly raised resting blood urea, and possibly a good or fairly good iirea concentration, but the failure in function will be shown by the second

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blood urea being much higher than the first. This combination of tests is nndoubtedly a more sensitive index of renal impairment in regard to nitrogen excretion than the use of both tests sepnrately. In using tests which involve estimations of urea in blood and urine, it must be remembered that they only indicate the efficiency of the kidneys in dealing with urea, which function, important though it is, is not necessarily an index of their capacity in other directions.

MUSEUM SPECIMENS.

NO 1.

HYDRONEPHROSIS AND CYST OF SUPRA- RENAL.

THE specimen represents a coronal section through a hydronephrosis which is combined with a cyst of the supra-renal gland.

The degree of renal atrophy is such, that only two small portions of kidney tissue remain. The lower sac, which represents the distended renal pelvis, shows the patches of inflammation on its mucous aspect, which are charac- teristically seen in specimens of hydronephrosis.

The glass rod indicates the pelvic outlet into the ureter, and its direction shoa s that the commencement of the latter structure is directed upwards, and is crossed and compressed by a renal blood vessel. This vascular relation- ship t o the ureter is a common complication of hydronephrosis.

The upper sac represents the supra-renal cyst, and it is lined with partly orgariised blood clot. On the lateral margins are two masses of tissue which have the macroscopical characteristics of supra-renal tissue. The portioii on the right can be seen to extend throughout the whole depth of the cyst wall.

A microscopical section through the upper margin of the sac shows thc presence of typical adrenal tissue.

The specimen was removed by operation from the left side of a woman aged fifty, who made a satisfactory recovery from her operation.

There was a history of attacks of indigestion and left-sided abdominal pain, accompanied by increased frequency of micturition extending over a period of six years.

The urine was slightly turbid with pus, and microscopically was found to contain coliform hacilli.

Cystoscopy showed effluxes of clear urine coming from the right ureteric orifice, but no sign of urinary excretion from the left ureteric orifice.

Indigo-carmine injected intravenously was excreted in good concentratioil from the right ureteric orifice in four minutes, but did not appear at all from the left within twenty minutes after the dye nas introduced.

On examination the left kidney was tender and enlarged.

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