Thiamine (Vitamin B1) deficiency is a metabolic disorder caused by inadequate intake, absorption, storage, or utilization of thiamine — a critical co-enzyme in carbohydrate metabolism and neuronal energy production.

Thiamine deficiency primarily affects organs with high energy demand:

• Brain

• Heart

• Peripheral nerves

Severe deficiency leads to two classic clinical syndromes:

If untreated, Wernicke encephalopathy progresses to Wernicke-Korsakoff syndrome, causing irreversible memory impairment.

2. Physiology & Pathophysiology

Thiamine (as Thiamine Pyrophosphate — TPP) is required for:

Mechanism of disease

Deficiency → impaired aerobic metabolism → lactic acidosis + neuronal injury

Organs affected first:

• Mammillary bodies

• Thalamus

• Cerebellum

• Peripheral nerves

• Myocardium

3. Types of Thiamine Deficiency

A. Dry Beriberi (Neurological)

Peripheral neuropathy predominates

B. Wet Beriberi (Cardiac)

High output cardiac failure

C. Infantile Beriberi

Occurs in breastfed infants of deficient mothers

D. Wernicke Encephalopathy

Acute neurological emergency

4. Risk Factors

Nutritional

• Starvation

• Polished rice diet

• Malnutrition

• Eating disorders

Medical

• Chronic diarrhoea

• Malabsorption syndromes

• Bariatric surgery

• Dialysis

• Hyperemesis gravidarum

• Cancer

Substance related

• Chronic alcoholism (most common worldwide cause)

Increased metabolic demand

• Sepsis

• Fever

• Pregnancy

• Hyperthyroidism

• Refeeding syndrome

Drug-related

• Loop diuretics

• Chemotherapy

• Prolonged IV glucose without vitamins

5. Clinical Features

A. Wernicke Encephalopathy (Medical Emergency)

Classic triad:

Other signs:

• Nystagmus

• Hypothermia

• Coma

• Hypotension

B. Dry Beriberi (Neurological)

• Symmetrical peripheral neuropathy

• Burning feet syndrome

• Reduced reflexes

• Muscle wasting

• Foot drop

C. Wet Beriberi (Cardiac)

• Tachycardia

• Wide pulse pressure

• Peripheral oedema

• Cardiomegaly

• High-output cardiac failure

• Pulmonary oedema

D. Infantile Beriberi

Occurs age 2–6 months:

• Hoarse cry (aphonia)

• Heart failure

• Vomiting

• Cyanosis

• Sudden death

6. Diagnostic Criteria

Diagnosis is clinical — treatment must not wait for labs.

Suspect in any patient with:

• Malnutrition + confusion

• Alcohol abuse + ataxia

• Heart failure without cause

• Neuropathy with poor diet

Response to thiamine confirms diagnosis.

7. Investigations

(Not required before treatment)

Supportive tests

• Blood lactate ↑

• Metabolic acidosis

• Low RBC transketolase activity

• MRI brain — mammillary body lesions

• Echocardiography — high output failure

Additional

• Electrolytes

• Liver function

• Magnesium (important cofactor)

8. Management

THIS IS A MEDICAL EMERGENCY

Glucose without thiamine → precipitates coma

Acute Treatment (Suspected Wernicke Encephalopathy)

Immediately:

High-dose parenteral thiamine

Recommended regimen:

• Thiamine 200–500 mg IV every 8 hours for 3 days

• Then 250 mg IV daily for 5 days

• Then oral therapy

Give magnesium supplementation if low.

Cardiac Failure (Wet Beriberi)

• IV thiamine → dramatic improvement within 24–48 hrs

• Diuretics cautiously

• Oxygen if pulmonary oedema

Peripheral Neuropathy

• Oral thiamine 100 mg daily for 3–6 months

9. Non-Pharmacological Management

Lifestyle

• Stop alcohol use

• Nutrition rehabilitation

• Treat malabsorption

Dietary advice

Increase thiamine-rich foods:

10. Prevention

Public health

• Food fortification programs

• Nutrition education

• Antenatal supplementation

Clinical prevention

Give thiamine prophylaxis to:

• Alcohol dependence

• Malnourished patients

• Before IV glucose infusion

• Prolonged vomiting

• Refeeding syndrome

11. Complications

Untreated leads to:

Key Clinical Message