Vitamin E, B6, Riboflavin and Biotin Deficiencies
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Direct answer
Vitamin E, B6, riboflavin and biotin deficiencies are uncommon, and each produces a recognisable syndrome linked to the vitamin's metabolic role. Vitamin E deficiency causes ataxia and neuropathy in fat malabsorption, B6 deficiency causes seizures and sideroblastic anaemia, riboflavin deficiency causes cheilosis and corneal vascularisation, and biotin deficiency causes dermatitis and alopecia.
What you must remember
- Vitamin E: a fat-soluble antioxidant whose deficiency causes spinocerebellar ataxia, peripheral neuropathy and pigmentary retinopathy, mainly in fat malabsorption.
- Vitamin E in preterm infants: haemolytic anaemia, because immature red cell membranes are vulnerable to oxidative damage.
- Vitamin B6: deficiency causes convulsions in infants, sideroblastic anaemia, glossitis and peripheral neuropathy, and isoniazid neuropathy is the classic drug-induced example.
- Pyridoxine-dependent epilepsy: an inherited form caused by an ALDH7A1 mutation, presenting with neonatal seizures that respond to pyridoxine.
- Riboflavin: deficiency causes angular stomatitis, cheilosis, glossitis and corneal vascularisation, and measuring erythrocyte glutathione reductase activity helps confirm it.
- Biotin: avidin in raw egg white binds biotin, and deficiency causes periorificial dermatitis, alopecia, conjunctivitis and neurological features.
- Biotinidase deficiency: an autosomal recessive defect detected by newborn screening, with features that respond to biotin.
- Assay interference: biotin supplements can falsely alter some immunoassays: sandwich assays such as troponin read falsely low, and thyroid tests can mimic hyperthyroidism.
Recognising each deficiency from its risk group
Each deficiency is recognised by a small set of signs, and the risk group usually points to the cause. Diet and drugs are often responsible, and malabsorption is the main clue for vitamin E.
| Vitamin | Key syndrome | Typical risk group |
|---|---|---|
| E | Ataxia, neuropathy, retinopathy | Cholestasis, cystic fibrosis, short bowel |
| B6 | Seizures, sideroblastic anaemia | Isoniazid, alcohol, malnutrition |
| B2 (riboflavin) | Cheilosis, glossitis, corneal vascularisation | Poor intake, alcohol, malnutrition |
| Biotin | Dermatitis, alopecia, neurological features | Raw egg white, parenteral feeding, some anticonvulsants |
Vitamin E deficiency is the one most tightly linked to malabsorption, so cholestatic or steatorrhoeic patients need it checked. In India, the B6 link matters in practice, because isoniazid is given to many tuberculosis patients and pyridoxine is commonly added for those at risk of neuropathy.
Micronutrient traps students fall into
Vitamin questions usually test the cofactor or the risk group rather than the textbook definition.
- Trap: attributing ataxia and neuropathy to vitamin B12 alone Correct: vitamin E deficiency produces the same picture in fat malabsorption, so the malabsorptive history is the clue.
- Trap: treating neonatal seizures as ordinary epilepsy without a trial of pyridoxine Correct: pyridoxine-dependent epilepsy should be considered, with a supervised pyridoxine trial during evaluation.
- Trap: accepting a falsely low troponin or a spurious thyroid result (for example low TSH with high free T4) at face value when the patient takes biotin Correct: check for biotin interference and repeat the test after stopping the supplement.
Frequently asked questions
Which vitamin deficiency causes ataxia and neuropathy in fat malabsorption?
Vitamin E deficiency causes spinocerebellar ataxia, peripheral neuropathy and retinopathy when fat absorption is impaired, as in cholestasis, cystic fibrosis or short bowel. Replacement is given orally or parenterally, depending on the severity of the malabsorption.
What is pyridoxine-dependent epilepsy?
Pyridoxine-dependent epilepsy is an inherited disorder caused by an ALDH7A1 mutation, presenting with neonatal seizures that stop after pyridoxine. Because treatment is simple and early seizure control protects the developing brain, a pyridoxine trial should be considered in any neonate with unexplained convulsions.
How is riboflavin deficiency confirmed in the laboratory?
Riboflavin deficiency is supported by measuring erythrocyte glutathione reductase activity, where the stimulation after adding flavin adenine dinucleotide in vitro is raised in deficiency. Cheilosis, angular stomatitis and glossitis at the bedside support the same diagnosis.
Why does raw egg white cause biotin deficiency?
Raw egg white contains avidin, a protein that binds biotin tightly and stops its absorption, so repeated consumption of raw egg can cause deficiency. Cooking denatures avidin, which is why the risk comes mainly from raw preparations.