and his colleagues, as well as others, under an analysis at once critical and imaginative.

Without doubt Addis's most original contribution to the treatment of kidney disease was his rest therapy. As he put it, "In dealing with a damaged or diseased organ, we must strive first of all to rest that organ from its work." Addis contrasted rest with "inactivity"—the former includes the very active processes of repair and regeneration. His focus on the work of urea excretion is now considered by most investigators to have been misguided and probably to have contributed to the disaffection of many with his ideas.

Why did Addis believe urea excretion to be the pivotal form of renal work? In rats a high-protein diet and unilateral nephrectomy both cause hypertrophy of the (remaining) renal mass; in fact, the renal growth curves in these two situations are almost identical. It is easy to see the basic stimulus to the remaining kidney after contralateral nephrectomy as an increased excretory workload. Since the most obvious consequence of a high-protein diet for the kidney is also excretion of larger amounts of urea (the final breakdown product of protein in the body and the major urinary solute), it was indeed logical for Addis to at least consider the osmotic excretory work of the kidney as a major factor in causing renal hypertrophy and thus in contributing to renal work.

One of the most revealing traits that we can observe in a human being is how he or she deals with apparent contradictions in his or her world view. Addis was quite aware of inconsistencies in his rest theory, in particular with the importance it assigned to the osmotic work of the kidney. The sophistication of his reasoning in holding to the osmotic theory in spite of these objections has often been overlooked in light of the resounding rejection the theory



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