My Doctor Said I Should Drink a Lot! Recommendations for Fluid Intake in Patients with Chronic Kidney Disease

Article Figures & Data

Table 1.

Relationship between solute and water intake in those with normal or impaired kidney concentrating ability

Urine concentrating capacity	Normal	Impaired
Urine osmolality (mOsmol/kg)	1200	600
Solute excretion (mOsmol)	800	800
Water needed = urine volume (ml)	670	1340
Water balance (food + oxidation − water loss; ml)	200	200
Drinking (ml)	470	1140

Table 2.

Conditions associated with high water intake: Those in which high water intake is indicated or not indicated^a

Condition	Comment
Conditions for which high fluid intake is indicated to prevent disease
urolithiasis	Generally, fluid intake should achieve a urine volume of 2.0 to 3.0 L/d
Conditions for which high fluid intake is recommended because of underlying disease
salt-wasting nephropathy (medullary cystic disease, other causes of chronic interstitial kidney disease)	Very rare disease; high salt intake (e.g., >400 mM/d NaCl) may be required to avoid hypotension; because these patients cannot appropriately concentrate the urine, high fluid intake (e.g., >4 L/d) may be needed
central and nephrogenic diabetes insipidus (genetic or acquired, e.g., lithium nephrotoxicity)	These patients often cannot raise urine to levels isosmotic with plasma; often large water intakes (e.g., >5 L/d) are needed to maintain water balance and a normal plasma osmolality
Conditions for which high fluid intake is not recommended
inappropriately high NaCl intake (′salt gluttony′) in the patient with CKD	The high NaCl intake “drives” the fluid intake; 24-h urine collection for creatinine (to assess completeness of the collection) and NaCl (to assess NaCl intake) will detect this condition; the appropriate management is to decrease salt intake
primary polydipsia because of the mistaken belief that high fluid intake is good for the kidney	This practice should be discouraged