Studies have been conducted to assess whether increased water intake will prevent renal disease (aside from kidney stone formation, as discussed earlier). The association between consumption of varying amounts of water intake and renal function was assessed in a study of eight men and one woman (Shore et al., 1988). As expected, urine volume decreased during water restriction and urine volume increased with water loading. These changes occurred without any effects on atrial natriuretic peptide levels. Plasma arginine vasopressin and plasma and urine osmolality were increased during water restriction and decreased during the water loading period (Shore et al., 1988). Similar changes in plasma osmolality and arginine vasopressin levels have been reported during water loading (Kimura et al., 1976). While no specific data were identified that would indicate that the volume of water consumed on a chronic basis was related to subsequent development of kidney diseases, such as glomerulonephritis or end-stage renal disease, total water consumption must be adequate to allow excretion of variable amounts of osmotically active ions and compounds that are the end products of dietary intake and metabolism; in healthy-functioning kidneys, it appears that homeostatic changes typically maintain water balance in spite of the wide range of dietary intakes (Shore et al., 1988).

There are no medications that directly stimulate water intake. However, certain anticholineric drugs may do so indirectly by producing a dry mouth. Also, in settings where decreased fluid intake has occurred, medications that improve metabolic and cognitive function should indirectly assist individuals to increase fluid intake. Examples of such medications include antibiotics for infection, insulin for unstable diabetes, and analgesics to control pain that has produced delirium. Antidepressant therapy may also stimulate improved fluid intake.

On the other hand, some medications produce excess water loss. In the situation of diuretic use, unintentional dehydration may occur when individuals reduce their fluid intake for some illness or behavior-related reason, yet continue with their diuretic treatments. This may occur clinically when a heart failure patient on chronic diuretics undergoes a bowel preparation for elective colonoscopy and loses excess fluid through the gastrointestinal tract during the preparation. Dehydration may also occur if the individual does not