To the Editor:—
According to current concepts of renal physiology, the end products of protein metabolism are excreted into the urine without any effort on the part of the kidney. That is to say, urea, sulfate and phosphate, along with most of the other constituents of the urine, pass the glomerular capsule by the physical process of filtration, energy being supplied by the heart. The work of the kidneys is carried on by the renal tubules; it is chiefly concerned with resorption from the glomerular filtrate of water, dextrose and physiologic salts which must be retained by the body. This work is rather constant and independent of the diet.Nevertheless, as brought out in the recent paper of Drs. Murphy and Rastetter discussed by Dr. Addis (The Journal, August 20, p. 668), restriction of protein in nephritis continues to be practiced with a view toward putting the kidneys at rest.