Water-Soluble Vitamins in Dialysis Patients
Water-soluble vitamins should be monitored and supplemented in dialysis patients due to increased requirements during kidney failure and significant losses during kidney replacement therapy. 1
Rationale for Supplementation
Water-soluble vitamins are particularly vulnerable in dialysis patients due to:
- Increased requirements during kidney failure and critical illness
- Significant losses in dialysate during treatment
- Poor nutritional intake in many dialysis patients
Specific Vitamin Losses and Requirements
High Priority Vitamins
- Vitamin C: Daily losses of approximately 68 mg in effluent during continuous kidney replacement therapy 1
- Folate: Daily losses of approximately 0.3 mg in effluent 1
- Thiamine (B1): Daily losses of approximately 4 mg in effluent 1
Other Water-Soluble Vitamins
- Vitamin B6 (Pyridoxine): Among the most deficient micronutrients (35.1%) in chronic hemodialysis patients 1
- Vitamin B2 (Riboflavin): Significant losses during dialysis sessions 2
Monitoring Recommendations
- Regular monitoring of serum levels of water-soluble vitamins is essential, particularly for patients on extended hours hemodialysis who may be at higher risk of deficiencies 3
- Special attention should be given to vitamin C, folate, and thiamine levels 1
Supplementation Guidelines
Standard Supplementation: Water-soluble vitamin supplementation should be provided to all dialysis patients 1
Dosing Considerations:
- Vitamin C: Suggested dosage of 100 mg/day 1
- Supplementation should be adjusted based on:
- Dialysis modality (hemodialysis vs. peritoneal dialysis)
- Duration of dialysis sessions (extended hours may require higher doses)
- Serum levels when available
Method of Administration:
- Post-dialysis supplementation is common practice
- Dose may need adjustment based on dialysis technique (conventional vs. hemodiafiltration) 4
Important Considerations
- Dialysis Technique: On-line hemodiafiltration may lead to greater losses of water-soluble vitamins compared to conventional hemodialysis 2
- Extended Hours Dialysis: Patients on extended hours hemodialysis (>15 hours/week) show higher rates of vitamin C deficiency and may require higher supplementation doses 3
- Membrane Type: Both high-flux and low-flux dialyzer membranes result in significant vitamin losses, requiring supplementation regardless of membrane type 5
Pitfalls to Avoid
- Oversupplementation: Excessive doses of B vitamins may exacerbate left ventricular diastolic dysfunction in CKD patients 6
- Vitamin C Overdose: Excessive vitamin C supplementation can lead to oxalate accumulation and increase risk of kidney stones 1
- Inadequate Monitoring: Relying solely on standard supplementation without periodic monitoring may miss individual deficiencies
By implementing appropriate monitoring and supplementation of water-soluble vitamins, clinicians can help prevent deficiencies that could negatively impact morbidity, mortality, and quality of life in dialysis patients.