Ideal Serum Sodium Level Prior to Dialysis
For patients with normal serum sodium (135-145 mEq/L), use a standard dialysate sodium concentration of 135-138 mEq/L, which represents the optimal maintenance target for most hemodialysis patients. 1, 2, 3
Normal Serum Sodium (135-145 mEq/L)
The optimal dialysate sodium concentration is 135-138 mEq/L for patients with normal serum sodium levels, as recommended by KDOQI guidelines. 1, 3
Dialysate sodium concentrations ≥140 mEq/L should be avoided because they increase thirst, interdialytic weight gain, hypertension, and cardiovascular workload. 1, 3
Sodium profiling (starting with high dialysate sodium and decreasing during treatment) must be avoided as it produces post-dialysis hypernatremia, increased thirst, and excessive interdialytic weight gain. 1, 2
Hypernatremia (>145 mEq/L)
When patients present with elevated serum sodium, the dialysate prescription requires immediate modification:
Begin with dialysate sodium 5-10 mEq/L below the patient's current serum sodium to create a controlled gradient for correction. 1, 2
Target a correction rate of 6-8 mEq/L per 24 hours and never exceed 0.5 mEq/L per hour to prevent cerebral edema and neurological injury. 1, 2
Reduce blood flow rate to 200-250 mL/min (instead of standard 300-400 mL/min) to limit solute clearance speed. 1, 2
Perform frequent serum sodium measurements during and after each session to detect overly rapid correction. 2
Transition to standard dialysate (135-138 mEq/L) only after serum sodium normalizes to <145 mEq/L. 1, 2
Hyponatremia (<135 mEq/L)
The management approach differs fundamentally based on severity:
Severe Hyponatremia (<130 mEq/L)
This represents a high-risk scenario associated with significantly increased all-cause mortality (hazard ratio 1.61) in incident dialysis patients. 4
The primary concern is preventing osmotic demyelination syndrome (ODS) from overly rapid correction. 3
Target correction rate of 4-6 mEq/L per 24 hours, not exceeding 8 mEq/L per 24 hours in high-risk patients or 10-12 mEq/L per 24 hours in average-risk patients. 3
Avoid dialysate sodium ≥140 mEq/L as this causes rapid sodium loading through diffusive transfer and accelerates correction dangerously. 3
Minimize ultrafiltration volume during initial sessions, as aggressive fluid removal combined with sodium diffusion accelerates correction. 3
Mild Hyponatremia (130-134 mEq/L)
Use standard dialysate sodium of 135-138 mEq/L with careful monitoring. 3
Address underlying causes including excessive free water intake between sessions and review fluid restriction (typically 1-1.5 L/day if hypervolemic). 3
Common Pitfalls to Avoid
Never use high dialysate sodium (≥140 mEq/L) routinely, as research demonstrates this increases interdialytic weight gain proportionally to the time-averaged dialysate sodium concentration. 5
Be aware that prescribed and measured dialysate sodium can differ by 2-3 mEq/L, particularly in facilities that mix concentrates on-site or use multiple different prescriptions. 6
Recognize that sodium profiling, despite reducing intradialytic hypotension, increases 24-hour blood pressure, interdialytic discomfort, and mean diastolic blood pressure. 7, 5
Monitor for neurological symptoms (confusion, seizures, altered consciousness) that could indicate ODS in hyponatremic patients or cerebral edema in hypernatremic patients. 2, 3