Makindo Medical Notes

⚠️ Safety Tip: Always check Vitamin B12 levels first. ❌ Never give folic acid alone in suspected or confirmed pernicious anaemia, as it can precipitate subacute combined degeneration of the spinal cord.

📖 About

Always check the BNF link here.

• 🧬 Essential vitamin for synthesis of nitrogenous bases in DNA and RNA.
• 🔄 Needed for red cell production and rapid cell turnover (pregnancy, haemolysis).

⚡ Mechanism of Action

• Coenzyme in one-carbon transfer reactions in purine/pyrimidine synthesis.
• Supports erythropoiesis and prevents megaloblastic changes.

🩺 Indications

• 👩‍🍼 Pre-pregnancy: reduces risk of neural tube defects.
• 🤰 First trimester: prevents neural tube defects; higher dose for high-risk women (epilepsy meds, diabetes, obesity, FHx NTDs).
• 🍽️ Folate deficiency – dietary, malabsorption, alcoholism, high metabolic states.
• 🩸 Chronic haemolytic anaemias (e.g. sickle cell, thalassaemia).
• 📉 Drug-induced folate deficiency (methotrexate, phenytoin, trimethoprim).

💊 Dose

• 📉 Folate deficiency: 5 mg PO OD for 4 months (up to 15 mg daily in severe deficiency).
• 🤰 Pregnancy: 5 mg PO OD from pre-conception until week 12 of pregnancy.
• 🧬 Chronic haemolysis: 5 mg PO daily (1–7x per week depending on severity).
• 📌 If B12 deficiency co-exists → replace both simultaneously.

⚠️ Interactions

• See BNF – interactions with anticonvulsants (phenytoin), antifolates (methotrexate, trimethoprim).

⚠️ Cautions

• ❌ Do not give in undiagnosed macrocytic anaemia until B12 deficiency excluded.
• Risk of masking B12 deficiency → can allow neurological damage to progress.

🚫 Contraindications

• Untreated or unrecognised Vitamin B12 deficiency (pernicious anaemia, dietary deficiency, malabsorption).
• Unexplained megaloblastic anaemia without full workup.

💥 Side Effects

• 🧠 Subacute combined degeneration of the spinal cord (if B12 deficiency not corrected at same time).
• 🤢 GI upset: dyspepsia, nausea, bloating.
• 🌡️ Rare: allergic reactions, pruritus, erythema.
• 🩸 May rarely precipitate seizures in predisposed patients on anticonvulsants.

📑 References

• BNF: Folic Acid
• UK Chief Medical Officer: Neural Tube Defect Prevention Guidance