Medicine – Vitamin Deficiencies

Vitamins are essential organic compounds required in relatively small amounts for normal metabolism, neurological function, blood formation, vision, bone health, coagulation and tissue maintenance. Deficiency may occur because of poor dietary intake, malabsorption, chronic illness, alcohol misuse, increased physiological requirements or medications that interfere with vitamin metabolism.

A useful first distinction is between fat-soluble vitamins A, D, E and K and the water-soluble B-group vitamins and vitamin C. Fat malabsorption therefore particularly predisposes to deficiencies of:

A, D, E and K.

1. Vitamin A Deficiency

Vitamin A is important for:

Vision.

Epithelial integrity.

Immune function.

Cell differentiation.

The retinal form of vitamin A participates in formation of visual pigments required for vision, particularly in:

Low-light conditions.

Causes of Vitamin A Deficiency

The original notes correctly include:

Protein-energy malnutrition.

Other important causes include:

Severe dietary deficiency.

Fat malabsorption.

Chronic cholestatic liver disease.

Pancreatic insufficiency.

Because vitamin A is fat-soluble, disorders that impair fat absorption can reduce its absorption.

Night Blindness

One of the earliest characteristic manifestations is:

Night blindness – nyctalopia.

The patient has difficulty seeing when moving from a bright environment into:

Dim light.

Therefore:

VITAMIN A DEFICIENCY → NIGHT BLINDNESS.

Xerophthalmia

More severe deficiency produces dryness of the:

Conjunctiva and cornea.

This is part of:

Xerophthalmia.

Characteristic ocular abnormalities can include:

Conjunctival xerosis.

Bitot spots.

Corneal xerosis.

Keratomalacia

Severe vitamin A deficiency may cause:

Keratomalacia.

This involves softening and destruction of the cornea and can result in:

Permanent blindness.

Therefore:

VITAMIN A → NIGHT BLINDNESS → XEROPHTHALMIA → KERATOMALACIA.

2. Vitamin B1 – Thiamine Deficiency

Thiamine – vitamin B1 is essential for carbohydrate metabolism and normal neurological and cardiac function.

Thiamine deficiency is particularly important because severe neurological deficiency can become:

A medical emergency.

Causes of Thiamine Deficiency

The original notes include:

Alcohol misuse

and

Dietary restriction.

Other causes include:

Severe malnutrition.

Prolonged vomiting.

Malabsorption.

Bariatric surgery.

Increased metabolic requirements.

Chronic alcohol misuse is particularly important because it can combine:

Poor intake + impaired absorption + reduced storage/utilisation.

3. Dry Beriberi

Neurological thiamine deficiency produces:

Dry beriberi.

Typical manifestations include:

Peripheral neuropathy.

Muscle weakness.

Reduced reflexes.

Sensory abnormalities.

Therefore:

DRY BERIBERI = MAINLY NEUROLOGICAL.

4. Wet Beriberi

Cardiovascular thiamine deficiency produces:

Wet beriberi.

This may cause:

Peripheral vasodilatation.

Tachycardia.

Oedema.

High-output cardiac failure.

Therefore:

WET BERIBERI = MAINLY CARDIOVASCULAR.

5. Wernicke Encephalopathy

Severe thiamine deficiency can cause:

Wernicke encephalopathy.

The classic triad is:

Confusion.

Ataxia.

Ocular abnormalities, such as ophthalmoplegia or nystagmus.

However, the complete triad is often absent.

Therefore thiamine should be given promptly when Wernicke encephalopathy is suspected.

6. Korsakoff Syndrome

Untreated or prolonged thiamine deficiency may progress to:

Korsakoff syndrome.

Typical features include:

Severe anterograde amnesia.

Memory impairment.

Confabulation.

The older combined term:

Wernicke–Korsakoff syndrome

describes the relationship between the acute encephalopathic and chronic amnestic manifestations.

7. Vitamin B2 – Riboflavin Deficiency

Riboflavin – vitamin B2 is required for flavin-containing coenzymes involved in:

Cellular energy metabolism.

Deficiency commonly occurs in association with:

General malnutrition.

Causes of Riboflavin Deficiency

The original notes include:

Protein-energy malnutrition.

Other situations associated with deficiency include:

Poor dietary intake.

Malabsorption.

Chronic alcohol misuse.

Deficiency often occurs together with other vitamin deficiencies rather than in isolation.

Clinical Features

Characteristic manifestations include:

Angular cheilitis/stomatitis.

Glossitis.

The tongue may become:

Red and inflamed.

Other mucocutaneous changes can also occur.

Therefore:

B2 DEFICIENCY → GLOSSITIS + ANGULAR STOMATITIS/CHEILITIS.

8. Niacin – Vitamin B3 Deficiency

Niacin – vitamin B3 is required for formation of:

NAD and NADP.

These coenzymes participate in numerous oxidation-reduction reactions and energy-producing pathways.

Causes of Niacin Deficiency

The original notes include:

Alcohol misuse.

Isoniazid.

Carcinoid syndrome.

Severe dietary deficiency or malabsorption can also cause niacin deficiency.

Carcinoid Syndrome and Niacin

Tryptophan can normally be used for:

Niacin synthesis.

In carcinoid syndrome, large amounts of tryptophan may be diverted toward:

Serotonin synthesis.

This reduces substrate available for niacin production and can contribute to:

Pellagra.

9. Pellagra

Niacin deficiency causes:

Pellagra.

The classic manifestations are remembered as the:

Four Ds.

Dermatitis.

Diarrhoea.

Dementia.

Death.

Pellagra Dermatitis

The dermatitis is characteristically:

Photosensitive.

It tends to affect sun-exposed skin.

A characteristic distribution around the neck is traditionally called:

Casal’s necklace.

Therefore:

NIACIN DEFICIENCY → PELLAGRA → 4 Ds.

10. Vitamin B6 – Pyridoxine Deficiency

Pyridoxine – vitamin B6 is important in:

Amino-acid metabolism.

Neurotransmitter synthesis.

Haem synthesis.

Causes of Vitamin B6 Deficiency

The original notes correctly include:

Isoniazid

and

Hydralazine.

Isoniazid is particularly important because it interferes with pyridoxine metabolism.

Clinical Features

Vitamin B6 deficiency may cause:

Peripheral neuropathy.

Glossitis.

Cheilosis.

Dermatitis.

It can also impair haem synthesis and produce:

Sideroblastic anaemia.

In severe deficiency, neurological manifestations such as seizures can occur.

Isoniazid and Pyridoxine

A classic examination association is:

ISONIAZID → B6 DEFICIENCY → PERIPHERAL NEUROPATHY.

Pyridoxine supplementation is therefore given to patients at increased risk of isoniazid-associated neuropathy.

11. Vitamin B12 – Cobalamin Deficiency

Vitamin B12 – cobalamin is essential for:

DNA synthesis.

Normal red-cell production.

Neurological function.

Myelin maintenance.

The image uses the term cyanocobalamin, which is one pharmaceutical form of vitamin B12; cobalamin is the broader physiological term.

Causes of Vitamin B12 Deficiency

Important causes include:

Pernicious anaemia.

Autoimmune gastritis.

Gastrectomy.

Terminal ileal disease or resection.

Crohn disease affecting the terminal ileum.

Severe dietary deficiency, especially prolonged strict vegan intake without supplementation.

Malabsorption.

Some medications, such as prolonged metformin use, can also contribute.

12. Pernicious Anaemia

Pernicious anaemia results from autoimmune loss of:

Intrinsic factor

and gastric parietal-cell dysfunction.

Intrinsic factor is required for B12 absorption in the:

Terminal ileum.

Therefore:

LOSS OF INTRINSIC FACTOR → B12 MALABSORPTION → B12 DEFICIENCY.

13. Haematological Features of B12 Deficiency

B12 deficiency impairs DNA synthesis and can produce:

Megaloblastic macrocytic anaemia.

Blood film may show:

Macro-ovalocytes.

Hypersegmented neutrophils.

14. Neurological Features of B12 Deficiency

Unlike isolated folate deficiency, B12 deficiency can cause significant:

Neurological disease.

Features include:

Peripheral neuropathy.

Loss of vibration sensation.

Loss of proprioception.

Sensory ataxia.

Spastic weakness.

Subacute Combined Degeneration

Severe B12 deficiency may cause:

Subacute combined degeneration of the spinal cord.

This predominantly affects:

Posterior columns

and

Corticospinal tracts.

Therefore:

B12 DEFICIENCY → MACROCYTIC ANAEMIA + NEUROLOGICAL DEFICITS.

15. Vitamin C Deficiency

Vitamin C – ascorbic acid is essential for normal:

Collagen synthesis.

It is also important for wound healing and enhances:

Non-haem iron absorption.

Humans cannot synthesise sufficient vitamin C and therefore depend on:

Dietary intake.

Cause of Vitamin C Deficiency

The major cause is:

Inadequate dietary intake.

Risk increases with:

Severe dietary restriction.

Malnutrition.

Alcohol misuse with poor diet.

Extreme food selectivity.

16. Scurvy

Vitamin C deficiency causes:

Scurvy.

Defective collagen formation leads to:

Fragile blood vessels and connective tissue abnormalities.

Clinical Features of Scurvy

Features include:

Swollen or bleeding gums.

Easy bruising.

Petechiae or perifollicular haemorrhage.

Poor wound healing.

Joint or bone pain.

Fatigue.

Therefore:

VITAMIN C DEFICIENCY → SCURVY → BLEEDING GUMS + BRUISING + POOR WOUND HEALING.

17. Vitamin D Deficiency

Vitamin D is essential for normal:

Calcium and phosphate homeostasis

and

Bone mineralisation.

Its active form is:

1,25-dihydroxyvitamin D – calcitriol.

Causes of Vitamin D Deficiency

The original notes include:

Renal failure

and

Dietary deficiency.

Important additional causes include:

Reduced sunlight exposure.

Fat malabsorption.

Cholestatic disease.

Severe liver disease.

18. Vitamin D and Chronic Kidney Disease

Advanced CKD does not simply cause a nutritional vitamin D deficiency.

The kidney normally converts 25-hydroxyvitamin D into:

Active calcitriol

through:

1α-hydroxylase.

In CKD:

↓ Functional renal mass

↓

↓ Calcitriol production

↓

↓ Intestinal calcium absorption

↓

Secondary hyperparathyroidism

↓

CKD-mineral and bone disorder.

Therefore the original term “renal failure → vitamin D deficiency” is directionally useful but physiologically simplified.

19. Rickets

Vitamin D deficiency in children causes:

Rickets.

Because growing bones are affected, manifestations can include:

Bowed legs.

Widened wrists.

Rachitic rosary.

Growth impairment.

20. Osteomalacia

In adults, defective mineralisation causes:

Osteomalacia.

Patients may develop:

Diffuse bone pain.

Proximal muscle weakness.

Fragility or insufficiency fractures.

Therefore:

VITAMIN D DEFICIENCY → RICKETS IN CHILDREN, OSTEOMALACIA IN ADULTS.

21. Vitamin E Deficiency

Vitamin E – tocopherol is an important:

Lipid-soluble antioxidant.

It protects cell membranes against:

Oxidative damage.

Causes of Vitamin E Deficiency

The original notes correctly include:

Fat malabsorption

and

Abetalipoproteinaemia.

Because vitamin E is fat-soluble, deficiency occurs particularly in disorders involving:

Chronic fat malabsorption.

22. Abetalipoproteinaemia

Abetalipoproteinaemia impairs the formation and transport of:

ApoB-containing lipoproteins.

This results in severe malabsorption and transport abnormalities involving:

Fat-soluble vitamins, particularly vitamin E.

23. Neurological Features of Vitamin E Deficiency

Vitamin E deficiency can cause:

Peripheral neuropathy.

Ataxia.

Loss of vibration and proprioception.

Hyporeflexia.

Spinocerebellar dysfunction.

Therefore the original description:

Spinocerebellar degeneration

captures an important manifestation but does not represent the full neurological picture.

Other Features

Vitamin E deficiency may also cause:

Haemolytic anaemia, particularly in susceptible patients.

A useful memory association is:

VITAMIN E DEFICIENCY → NEUROLOGICAL DYSFUNCTION + HAEMOLYSIS.

24. Vitamin K Deficiency

Vitamin K is required for normal activation of several:

Coagulation factors.

It acts as a cofactor for:

γ-carboxylation

of vitamin K-dependent proteins.

Vitamin K-Dependent Factors

The major vitamin K-dependent coagulation factors are:

II, VII, IX and X.

Vitamin K is also required for:

Protein C

and

Protein S.

25. Causes of Vitamin K Deficiency

The original notes correctly include:

Biliary obstruction

and

Antibiotic therapy.

Other causes include:

Fat malabsorption.

Poor dietary intake in susceptible patients.

Neonatal deficiency.

26. Biliary Obstruction and Vitamin K

Vitamin K is:

Fat-soluble.

Normal absorption therefore requires adequate:

Bile salts.

In biliary obstruction, reduced bile delivery to the intestine impairs fat absorption.

Therefore:

BILIARY OBSTRUCTION → ↓ VITAMIN K ABSORPTION → BLEEDING TENDENCY.

27. Antibiotics and Vitamin K

Prolonged broad-spectrum antibiotic treatment can reduce:

Intestinal bacterial contribution to vitamin K availability.

This becomes more important when combined with:

Poor nutrition

or

Malabsorption.

28. Consequences of Vitamin K Deficiency

Vitamin K deficiency impairs coagulation and produces:

Bleeding tendency.

Possible manifestations include:

Easy bruising.

Mucosal bleeding.

GI bleeding.

Haemorrhage in severe cases.

Laboratory testing commonly shows early prolongation of:

Prothrombin time – PT/INR, because factor VII has a relatively short half-life.

29. Fat-Soluble Vitamins – Note Form

Vitamin A:

Deficiency → night blindness, xerophthalmia, Bitot spots, keratomalacia.

Vitamin D:

Deficiency/impaired activation → defective bone mineralisation.

Children → rickets.

Adults → osteomalacia.

Vitamin E:

Deficiency → neuropathy, ataxia, spinocerebellar dysfunction ± haemolysis.

Vitamin K:

Deficiency → impaired coagulation and bleeding.

30. Water-Soluble Vitamins – Note Form

B1 – Thiamine:

Dry beriberi → neuropathy.

Wet beriberi → high-output heart failure.

Wernicke encephalopathy → confusion + ataxia + ocular abnormalities.

Korsakoff syndrome → severe memory impairment/confabulation.

B2 – Riboflavin:

Glossitis.

Angular stomatitis/cheilitis.

B3 – Niacin:

Pellagra.

Dermatitis + diarrhoea + dementia + death.

B6 – Pyridoxine:

Peripheral neuropathy.

Glossitis.

Sideroblastic anaemia.

Classic drug association → isoniazid.

B12 – Cobalamin:

Megaloblastic anaemia.

Peripheral neuropathy.

Subacute combined degeneration.

Vitamin C:

Scurvy.

Bleeding gums.

Bruising.

Poor wound healing.

31. Important Corrections and Additions

The original vitamin A section is correct, but an important additional classic finding is:

BITOT SPOTS.

For vitamin B1, Wernicke encephalopathy and Korsakoff syndrome are related but clinically distinct:

WERNICKE = ACUTE NEUROLOGICAL EMERGENCY.

KORSAKOFF = CHRONIC AMNESTIC SYNDROME.

For niacin, remember the classic:

4 Ds → DERMATITIS + DIARRHOEA + DEMENTIA + DEATH.

For vitamin B6, an important additional manifestation is:

SIDEROBLASTIC ANAEMIA.

For vitamin B12, the key distinction from folate deficiency is:

B12 DEFICIENCY CAN CAUSE NEUROLOGICAL DAMAGE.

For vitamin D, advanced CKD particularly causes:

IMPAIRED ACTIVATION OF VITAMIN D TO CALCITRIOL, contributing to secondary hyperparathyroidism and CKD-mineral and bone disorder.

For vitamin E, the consequences extend beyond spinocerebellar degeneration and include:

PERIPHERAL NEUROPATHY + ATAXIA ± HAEMOLYTIC ANAEMIA.

For vitamin K, the key mechanism is failure of normal activation of:

FACTORS II, VII, IX AND X + PROTEINS C AND S.

Key Clinical Pattern

For rapid recall:

A → EYES → NIGHT BLINDNESS / XEROPHTHALMIA.

B1 → BRAIN + NERVES + HEART → WERNICKE / BERIBERI.

B2 → MOUTH → GLOSSITIS + ANGULAR CHEILITIS.

B3 → 4 Ds → DERMATITIS + DIARRHOEA + DEMENTIA + DEATH.

B6 → ISONIAZID → NEUROPATHY ± SIDEROBLASTIC ANAEMIA.

B12 → BLOOD + SPINAL CORD → MEGALOBLASTIC ANAEMIA + SUBACUTE COMBINED DEGENERATION.

C → COLLAGEN → SCURVY + BLEEDING GUMS + POOR WOUND HEALING.

D → BONE → RICKETS / OSTEOMALACIA.

E → NEUROLOGICAL DYSFUNCTION ± HAEMOLYSIS.

K → KOAGULATION → BLEEDING.

And remember the fat-soluble vitamins simply as:

A – D – E – K.