Treatment of Vitamin B6 Deficiency
For suspected vitamin B6 deficiency resulting from chronic poor dietary intake, oral supplementation with 50-100 mg daily for 1-2 weeks is safe, widely available, and effective. 1
Initial Assessment and Diagnosis
Measure plasma pyridoxal phosphate (PLP) levels to confirm deficiency (normal range: 20-200 nmol/L; deficiency defined as <20 nmol/L). 1 In patients with inflammation, low albumin, or serious illness, red cell PLP measurements are more reliable than plasma measurements for differentiating true from apparent deficiency. 1
Standard Treatment Protocol
Oral Supplementation for Dietary Deficiency
- Administer 50-100 mg pyridoxine orally daily for 1-2 weeks for deficiency from chronic poor dietary intake. 1
- This dose is safe, widely available, and responds rapidly to treatment. 1
- PLP levels reflect liver stores and plateau within 6-10 days of treatment initiation. 1
High-Risk Populations Requiring Special Attention
Elderly patients represent a particularly vulnerable group, with deficiency affecting 49% of community-dwelling and 75% of institutionalized elderly in the UK. 2 The elderly have markedly increased requirements, potentially needing 1.96-2.0 mg/day or even 3-4.9 mg/day to maintain adequate plasma PLP levels and prevent hyperhomocysteinemia. 1, 3
Pregnant women require higher intakes up to 2 mg/day. 3 Pregnancy is specifically identified as a high-risk condition for deficiency. 1
Other high-risk populations include:
- Alcoholics 1
- Renal dialysis patients (especially continuous renal replacement therapy) 1
- Post-operative patients 1
- Patients with infections or critical illness 1
- Patients receiving medications that inhibit vitamin B6 activity (isoniazid, penicillamine, anti-cancer drugs, corticosteroids, anticonvulsants) 1
Special Clinical Situations
Isoniazid Overdose
For acute deficiency with isoniazid-induced seizures, administer 5 g pyridoxine (1 g per gram of isoniazid ingested, then 1 g IM or IV every 30 minutes up to maximum 5 g). 1
Ethylene Glycol Poisoning
Administer 50 mg pyridoxine IV every 6 hours as part of treatment protocol. 1
Dialysis Patients
Despite potential for B6 elevation, vitamin B6 supplementation is recommended in dialysis patients as deficiency contributes to hyperhomocysteinemia. 4 Oral supplementation of 30 mg daily has been shown effective in eliminating sensory abnormalities in elderly dialysis patients within one month. 5
Monitoring and Follow-Up
Check vitamin B6 levels 3 months after starting supplementation to verify normalization. 2 Once levels normalize, monitor annually in stable patients. 4 For patients with conditions increasing B6 requirements (chronic kidney disease, dialysis), monitor every 3 months until stabilization. 4
Clinical Manifestations to Assess
Deficiency causes:
- Seborrheic dermatitis with cheilosis and glossitis 1
- Microcytic anemia 1
- Epileptiform convulsions 1
- Confusion and/or depression 1
- Angular stomatitis 1
- Peripheral neuropathy (paresthesia, burning dysesthesias, thermal sensations) 5
Safety Considerations
Avoid prolonged doses exceeding 100 mg/day as long-term use at this level has been associated with Lhermitte signs suggesting spinal cord effects. 1 Doses above 300 mg/day have been related to negative effects, and large supplemental doses (>500 mg/day) can cause sensory neuropathy with ataxia, areflexia, impaired cutaneous and deep sensations, and dermatologic lesions. 1
Nutritional Support Regimens
For patients on enteral nutrition, deliver at least 1.5 mg pyridoxine per day in 1500 kcal. 1 For parenteral nutrition, provide 4-6 mg pyridoxine per day. 1