Lithium decreases sodium reabsorption by the renal tubules which could lead to sodium depletion. Lithium is excreted primarily by the kidney; adequate renal function and adequate salt and fluid intake are essential in order to avoid lithium accumulation and intoxication. Diminished intake of excessive loss of salt and fluids, as a result of vomiting, diarrhea, perspiration or use of diuretics will also increase lithium retention. If diuretics are used during lithium therapy the serum lithium concentration must be closely monitored.