Makindo Medical Notes

Folate supplementation should be provided to anyone in early pregnancy or planning pregnancy to prevent neural tube defects in the baby.

About

• Folic acid fortification in flour is mandatory in the UK to prevent neural tube defects in babies.
• Folate, a B9 vitamin, is naturally present in green vegetables, legumes, and some fruits.

Aetiology

• Folate stores last approximately 4 months but deficiency can develop rapidly in individuals with poor intake.
• Absorbed in the terminal ileum, almost 50% of folate is stored in the liver.
• Folate is essential for DNA synthesis.
• Deficiency first manifests in rapidly turning-over cells, leading to conditions like megaloblastic anaemia and glossitis.

Causes

• Malabsorption: Coeliac disease, tropical sprue, jejunal resection, inflammatory bowel disease.
• Diet: Poor intake (malnutrition, alcohol excess, anorexia, food fads), particularly in the elderly or those with poor social conditions.
• Increased Requirements: Pregnancy, lactation, prematurity, malignancy (leukaemia, carcinoma), chronic blood disorders (haemolytic anaemia, sickle cell disease).
• Metabolic Disorders: Homocystinuria.
• Dialysis: Haemodialysis or peritoneal dialysis leading to excessive urinary excretion.
• Drug-Induced Deficiency: Anticonvulsants, phenytoin, trimethoprim, methotrexate, alcohol, nitrofurantoin, sulfasalazine.
• Genetic Disorders: SLC46A1 gene mutations causing folate transporter deficiency.

Clinical Features

• Macrocytic anaemia and glossitis.
• Neurological symptoms such as paraesthesia, numbness, peripheral neuropathy, or psychiatric disturbances (e.g., depression).

Differential Diagnoses

• Vitamin B12 deficiency.
• Macrocytosis: Pregnancy, alcohol excess, liver disease, reticulocytosis, hypothyroidism.
• Aplastic anaemia, sideroblastic anaemia, pure red cell aplasia.

Investigations

• FBC and Blood Film: Features of megaloblastic anaemia with hypersegmented polymorphs.
• Mean Corpuscular Volume (MCV): Typically >96 fL.
• Serum Folate: Levels <7 nmol/L (<3 µg/L) indicate a deficiency. Note that recent folate intake can give false reassurance.
• Red Cell Folate: A better long-term indicator of folate status than serum folate.
• Vitamin B12 Levels: Should be checked and replaced if low.

Management

• Folic acid 5 mg daily for 4 months (until term for pregnant women).
• In malabsorption states, 15 mg daily may be required.
• Treat any underlying causes (e.g., coeliac disease).
• Ensure Vitamin B12 is replaced if deficient to prevent subacute combined degeneration of the spinal cord.

References

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Revisions

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