Vitamin Deficiencies and Their Syndromes: Diagnosis and Treatment
Vitamin deficiencies require immediate recognition and specific treatment protocols to prevent irreversible complications, with B12 deficiency being particularly critical due to risk of permanent neurological damage if untreated for more than 3 months. 1
Vitamin B12 Deficiency
Clinical Presentation and Diagnosis
- Neurological manifestations include peripheral neuropathy, subacute combined degeneration of the spinal cord, cognitive impairment, and gait disturbances 2, 3
- Hematologic findings include megaloblastic anemia with elevated MCV 3
- Biochemical diagnosis requires serum B12 <150 pmol/L (<203 pg/mL), or levels between 140-200 pmol/L with elevated methylmalonic acid >271 nmol/L or homocysteine >15 μmol/L 3
Treatment Protocol
For patients WITH neurological involvement:
- Hydroxocobalamin 1 mg IM on alternate days until no further improvement 2
- Then hydroxocobalamin 1 mg IM every 2 months for maintenance 2
- Seek urgent specialist advice from neurologist and hematologist 2
For patients WITHOUT neurological involvement:
- Hydroxocobalamin 1 mg IM three times weekly for 2 weeks 2
- Then maintenance with 1 mg IM every 2-3 months lifelong 2
Critical Pitfall
Never administer folic acid before treating B12 deficiency, as it may mask the anemia while allowing irreversible subacute combined degeneration of the spinal cord to progress 2, 1
Thiamine (Vitamin B1) Deficiency
Clinical Syndromes
- Wernicke's encephalopathy presents with confusion, ataxia, and ophthalmoplegia—a medical emergency 2
- Beriberi causes peripheral neuropathy and cardiac dysfunction 2
Treatment
- For prolonged vomiting, dysphagia, or suspected acute deficiency: thiamine 200-300 mg daily orally PLUS vitamin B compound strong 1-2 tablets three times daily 2
- For patients unable to tolerate oral intake or with clinical suspicion of acute deficiency: full-dose intravenous thiamine immediately 2
- Never give glucose to patients at risk of thiamine deficiency before thiamine replacement, as this can precipitate Wernicke-Korsakoff syndrome 2
Folate (Vitamin B9) Deficiency
Treatment Protocol
- Always check and treat B12 deficiency FIRST before initiating folate treatment 2
- Folic acid 5 mg orally daily for minimum 4 months 2
- Further investigations if malabsorption suspected 2
Special Populations
- Women with BMI <29.9 kg/m² planning pregnancy: 400 mcg daily until 12 weeks gestation 2
- Women with BMI >30 kg/m² or type 2 diabetes: 5 mg daily until 12 weeks gestation 2
Vitamin A Deficiency
Clinical Presentation
- Night blindness (nyctalopia) and xerophthalmia are hallmark features 2
- Reduced fertility in males and risk of fetal abnormalities 2
Treatment
- Adults: 10,000-25,000 IU oral vitamin A daily for 1-2 weeks 2
- Recheck levels at 3 months 2
- If no response to oral treatment, refer for specialist assessment and consideration of IM injections 2
- Adolescents: refer for specialist support 2
Vitamin D Deficiency
Clinical Consequences
- Osteopenia, osteoporosis, and increased fracture risk 4
- Rickets in children 4
- Associated with increased risk of cardiovascular disease, autoimmune diseases, and infections 4
Treatment
- Follow local guidelines or Royal Osteoporosis Society recommendations for loading doses 2
- Maintenance: 800-1000 IU daily to achieve 25-OH vitamin D >75 nmol/L (>30 ng/mL) 4
- Higher maintenance doses often required despite good adherence 2
Vitamin E Deficiency
Clinical Features
- Peripheral neuropathy, muscle weakness, and ataxia 2
Treatment
- Oral vitamin E 100-400 IU daily 2
- Recheck levels after 3 months 2
- Adjust for serum lipids when assessing nutritional status 2
- If no response, refer for specialist assessment and consideration of IM injections 2
- Caution: Large vitamin E doses can exacerbate vitamin K deficiency and affect coagulation 2
Vitamin K Deficiency
Treatment
- 1-2 mg oral vitamin K daily (Ketovite tablets, menadiol sodium phosphate, or phytomenadione) 2
- Recheck levels after 3 months 2
- For patients on anticoagulants (warfarin): refer to specialist for assessment 2
Zinc and Copper Deficiency
Diagnostic Approach
- Always check both zinc AND copper levels together, as they affect each other's absorption 2
Treatment Algorithm
If both zinc and copper are low:
- Two Forceval capsules daily for 3 months, then recheck 2
Mild deficiency of either:
- Two Forceval capsules daily for 3 months, then recheck 2
Severe zinc deficiency with normal/borderline copper:
- High-dose zinc supplement for 3 months, then recheck 2
- If no improvement or copper falls, refer for specialist advice 2
Severe copper deficiency:
- Refer for specialist advice immediately 2
Critical Ratio
- Maintain 8-15 mg zinc to 1 mg copper ratio when supplementing 2
- Close monitoring required with higher doses 2
Iron Deficiency Anemia
Evaluation
- Always investigate and exclude sources of blood loss before treating 2
Treatment
- Follow NICE CKS Anaemia—iron deficiency guidelines for patients >12 years and pregnant women 2
Unexplained Anemia or Fatigue
Workup
- Investigate for protein, zinc, copper, and selenium deficiencies when standard causes excluded 2
Key Monitoring Principles
- Vitamin B12: Check levels every 3 months until stabilization, then annually 3
- Fat-soluble vitamins (A, E, K): Recheck at 3 months after initiating treatment 2
- Zinc and copper: Recheck at 3 months 2
Universal Precautions
- Classic vitamin deficiency syndromes (scurvy, beriberi, pellagra) are uncommon in Western societies but suboptimal intake remains common, especially in elderly populations 5
- High-risk groups include pregnant women, children, adolescents, elderly, and the 800+ million undernourished people globally 6
- Fat-soluble vitamins (A, D, E, K, B12) can accumulate and cause toxicity with excessive supplementation 7
- Most water-soluble vitamins are excreted through kidneys and rarely accumulate 7