Journal Club - Water intake in CKD improves or worsens disease?

Hydration is an important aspect of nutrition that should receive more attention. The 2010 European Food Safety Authority guidelines recommend a total water intake of 2.5 L/day for men and 2 L/day for women. The kidneys play a central role in controlling water balance, a function that is impaired in chronic kidney disease (CKD), which affects 10–15% of the population worldwide.  

We all know that chronic kidney disease (CKD) means your kidneys are damaged and can`t filter blood the way they should. The main risk factors for developing kidney disease are diabetes, high blood pressure, heart disease, and a family history of kidney failure.

 A recent study reveals that the relation between plain water intake and progression to kidney failure is not linear but U-shaped in patients with chronic kidney disease (CKD). This implies that both low and high water intake may not be beneficial for CKD patients. The study appears in the journal Nephrology Dialysis Transplantation. 

Based on the study, the authors suggest, an optimum range of 1–2 L/day water intake for CKD patients that still needs to be confirmed. Not much is known about optimal daily water intake for preventing CKD progression. The Study also aimed to assess the relation of kidney outcomes in patients with CKD to total and plain water intake and urine volume taking into account the kidneys urine-concentrating ability. 

For the purpose, the researchers included 1265 CKD patients with a median age of 69 years. They assessed fluid intake at baseline interviews, collected 24-h urine volumes and estimated urine osmolarity.  Based on the study, the researchers found patients; median daily intake was 2.0 L for total water and 1.5 L for plain water, median urine volume was 1.9 L/24.

Neither total water intake nor urine volume was associated with either kidney outcome. Kidney failure risk increased significantly with decreasing estimated urine osmolarity. High plain water intake was also significantly associated with faster eGFR decline.

The authors hence concluded that these findings may have important clinical implications for CKD management.