Table 3.

Hydration Status and Chronic Diseases

Chronic Disease	Evidence Level*	Findings
Urolithiasis	Strong	Increased urine volume from increased fluid intake reduces stone recurrence. Favorable associations between increased hydration status and lower stone recurrence rate.
Bronchopulmonary Disorders	Strong	Exercise related asthma is linked with low fluid intake.128
Hypertonic Dehydration in Infants	Less strong	In infants with gastroenteritis, a high urine osmolality due to a high protein and sodium content of formula and weaning foods increases the risk of hypertonic dehydration.129
Diabetic Hyper glycemia and Ketoacidosis	Less strong	In diabetics, experimentally induced dehydration promotes development of hyperglycemia.130 Higher serum osmolality at time of hospital admission was the most important predictor of death in children with diabetic ketoacidosis.131
Morphological and Functional Changes in the Kidney	Weaker	In patients with polycystic kidney disease and chronic renal failure, sustained high urine volumes with urine osmolalities below plasma osmolality accelerate the decline of glomerular filtration rate.132
Hypertension	Weaker	In diabetic patients, lower urine flow and sodium excretion rates are associated with higher blood pressure during the day and a reduced fall in blood pressure at night.133 In a study of 1688 healthy men, a low urine production day-to-night ratio was not associated with hypertension.134 In one study, eight male hypertensive volunteers and eight controls were exercised in a hot environment with or without water ingestion. In hypertensive men, water ingestion increased exercise-related differences in their systolic and diastolic blood pressure.
Fatal Coronary Heart Disease	Weaker	High intake of water is associated with lower risk of fatal heart disease.135
Venous Thromboembolism	Weaker	High serum osmolality after stroke is associated with increased rate of thromboembolism.136
Cerebral Infarct (Stroke)	Weaker	Increased serum osmolality or hematocrit is associated with increased risk of stroke morbidity/mortality.137, 138 Stroke patients with initial mid-range hematocrit have better discharge outcomes.139
Dental Diseases	Weaker	Salivary output decreases with dehydration. Hypohydration may be linked with dental disease.
Urinary Tract Infection (UTI)	Weaker	Occurrence of UTI is associated with low fluid intake or low urine output.140, 141 No definitive evidence links susceptibility to UTI to fluid intake.
Bladder and Colon Cancer	Inconsistent	Generally show no association between fluid intake and cancer risk or tumor recurrence.142–144
Gallstone	Speculative	Water intake induces gallbladder emptying suggestive that a high daily water intake may prevent gallstone formation.145
Mitral Valve Prolapse	Speculative	Mitral valve prolapse developed after dehydration in one in 10 healthy men.146
Glaucoma	Speculative	Dehydration reduces intraocular pressure and elevated colloid osmotic pressure.147 Intraocular pressure increases minutes after water ingestion and remains elevated above baseline for up to 45 minutes post-ingestion.148

^*Categories of evidence: Described in Table 2