Hydration for Adult Patients with Nephrolithiasis: Specificities and Current Recommendations

Abstract

Nephrolithiasis affects around 10% of the population and is frequently associated with impaired dietary factors. The first one is insufficient fluid intake inducing reduced urine volume, urine supersaturation, and subsequently urinary lithiasis. Kidneys regulate 24 h urine volume, which, under physiological conditions, approximately reflects daily fluid intake. The aim of this study is to synthesize and highlight the role of hydration in the treatment of nephrolithiasis. Increasing fluid intake has a preventive effect on the risk of developing a first kidney stone (primary prevention) and also decreases the risk of stone recurrence (secondary prevention). Current guidelines recommend increasing fluid intake to at least at 2.5 L/day to prevent stone formation, and even to 3.5–4 L in some severe forms of nephrolithiasis (primary or enteric hyperoxaluria or cystinuria). Fluid intake must also be balanced between day and night, to avoid urinary supersaturation during the night. Patients should be informed and supported in this difficult process of increasing urine dilution, with practical ways and daily routines to increase their fluid intake. The liquid of choice is water, which should be chosen depending on its composition (such as calcium, bicarbonate, or magnesium content). Finally, some additional advice has to be given to avoid certain beverages such as those containing fructose or phosphoric acid, which are susceptible to increase the risk of nephrolithiasis.

Causal associations between 45 dietary intake habits and urolithiasis: insights from genetic studies

“…Many studies have shown that low urine volume is a risk factor for kidney stones, and adequate intake of drinking water can prevent kidney stone formation. A large amount of water intake can dilute the concentration of urine, prevent the formation of crystals of uric acid, oxalate, and other chemical components in urine, and promote their excretion ( 41 - 44 ). However, unexpectedly, the MR analysis in our study did not show a significant association between water intake and kidney or ureteral stones, although water intake was found to reduce the risk of bladder and other lower urinary tract stone formation.…”