1. Balance studies have been made on three dogs before and after adrenalectomy, performed in two stages.
2. It has been shown that the sodium concentration of the blood decreases in adrenalectomized dogs, as is true in patients suffering from Addison's disease and in cats experimentally adrenalectomized.
3. There are also decreases in the chloride and bicarbonate concentrations which together are approximately equivalent to the decrease in sodium.
4. An increase in the potassium concentration of the blood occurs after adrenalectomy, as reported in other studies. There is no obvious correlation of this change with changes in potassium balances.
5. The balance studies show a striking loss of sodium from the body during the development of adrenal insufficiency. This loss of Na results from an increased excretion of sodium in the urine and is not complicated by loss of base as a result of vomiting or diarrhea.
6. Following adrenalectomy, both the total amount of sodium and its concentration in the urine are markedly increased. This increase in concentration of sodium occurs in spite of an augmented urine volume.
7. The behavior of the chloride ion following adrenalectomy parallels that of the sodium ion, but the loss is not equivalent.
8. During the period of accumulation of non-protein nitrogen in the blood, the rate of water excretion by the kidney is even greater than before removal of the adrenal glands.
9. The possibility of a regulatory effect of the adrenal glands upon sodium metabolism and renal function has been discussed.