The fact that the skin and the kidneys can act, to a certain extent, vicariously, seems to be generally accepted, as is manifest by the use of sweat-baths in the treatment of uremia. The skin excretes, qualitatively, practically the same substances which occur in the urine, namely, urea, ammonia, uric acid, amino-acids,1 creatinin,2 chlorids, phosphates, sulphates and certain enzymes.3 The quantity of these substances, however, excreted by the skin is, normally, far less than that eliminated through the kidneys.
In health the ratio of the quantities of the various urinary constituents to one another is fairly constant, independent of the actual amounts of the substances eliminated by the kidney. Moreover, this ratio for urine differs from that existing between the same substances in the blood-stream. Hence the kidney exercises a selective concentrating action for certain substances. The question then suggests itself as to whether
PLAGGEMEYER HW, MARSHALL EK. A COMPARISON OF THE EXCRETORY POWER OF THE SKIN WITH THAT OF THE KIDNEY THROUGH A STUDY OF HUMAN SWEAT. Arch Intern Med (Chic). 1914;XIII(1):159–168. doi:10.1001/archinte.1914.00070070164009