Thiamine-Biologic action, Requirements, Dietary sources, Deficiency, Diagnosis, Treatment

THIAMINE (VITAMIN B1)
The active form of thiamine is Thiamine pyrophosphate (TPP)
GLUCOSE METABOLISM AND CELLULAR ENERGY GENERATION
TPP acts as a cofactor for
▪︎ pyruvate dehydrogenase in oxidative decarboxylation
▪︎ transketolase in HMP shunt pathway of glucose metabolism
▪︎ alpha ketoglutarate dehydrogenase in citric acid cycle
2. NUCLEIC ACID AND FATTY ACID SYNTHESIS
3. NERVE CONDUCTION (by synthesis of acetylcholine)

Recommended daily allowance is 0.4 mg/1000 Cal of carbohydrate intake.
⊙ 0 to 6 months - 0.2 mg
⊙ 6 to 12 months - 0.3 mg
⊙ 1 to 3 years - 0.5 mg
⊙ 4 to 8 years - 0.6 mg
⊙ 9 to 13 years - 0.9 mg
⊙ 14 years and above - 1.2 mg

Requirement of thiamine is increased …….
When carbohydrates are taken in large amounts
During periods of increased metabolism

Dietary sources

•Breast milk of well nourished mother
•Cow milk (Thiamine is sensitive to pasteurization and heat)
•Unpolished grains (Polishing removes thiamine rich aleurone layer)
•Eggs
•Organ meats
•Legumes
Parboiling of rice retains Thiamine and other vitamins

Thiamine deficiency results in Beriberi
At risk groups : groups with diets based on polished rice and severely malnourished.
Three forms of beriberi :
▪︎ Dry beriberi
▪︎ Wet beriberi
▪︎ Infantile beriberi

Clinical manifestations of beriberi

• Dry beriberi : peripheral neuritis, paralysis of lower limbs, loss of deep tendon reflexes, muscle wasting, loss of position sense

• Wet beriberi : congestive cardiac failure and pulmonary edema

• Infantile beriberi : cardiomegaly, cyanosis, dyspepsia and aphonia (paralysis of laryngeal nerve)

WERNICKE ENCEPHALOPATHY:
~ occurs in infants and children with severe deficiency
~ TRIAD :
Mental state changes
Ocular signs
Ataxia
~ Thalamus and periventricular gray matter show hemorrhagic lesions

Diagnosis

⊙ 24 hours urinary thiamine excretion - less than 15 μg/day
(Normal excretion is 40 to 100 μg/day in children)
⊙ Response of red cell transketolase to addition of TPP
over 25% increase - severe deficiency
15 to 25% increase - mild deficiency
(Normally there is less than 15% increase in response)
⊙ Serum lactate and pyruvate levels - raised

Treatment

▪In children with mild beriberi - Thiamine 5 mg/day orally
▪In︎ severely ill children- Thiamine 10 mg BD intravenously
▪In children with fulminant heart disease - high doses of Thiamine + treatment of congestive heart failure

1. Thiamine (Vitamin B1) Angelin.A 3rd MBBS

2. Outline Biologic action Requirements Dietary sources Deficiency Diagnosis Treatment

3. Biologic action The active form of thiamine is Thiamine pyrophosphate (TPP) GLUCOSE METABOLISM AND CELLULAR ENERGY GENERATION TPP acts as a cofactor for ▪︎ pyruvate dehydrogenase in oxidative decarboxylation ▪︎ transketolase in HMP shunt pathway of glucose metabolism ▪︎ alpha ketoglutarate dehydrogenase in citric acid cycle 2. NUCLEIC ACID AND FATTY ACID SYNTHESIS 3. NERVE CONDUCTION ( by synthesis of acetylcholine)

4. Requirements Recommended daily allowance is 0.4 mg/1000 Cal of carbohydrate intake . ⊙ 0 to 6 months - 0.2 mg ⊙ 6 to 12 months - 0.3 mg ⊙ 1 to 3 years - 0.5 mg ⊙ 4 to 8 years - 0.6 mg ⊙ 9 to 13 years - 0.9 mg ⊙ 14 years and above - 1.2 mg

5. Requirement of thiamine is increased ……. When carbohydrates are taken in large amounts During periods of increased metabolism

6. Dietary sources •Breast milk of well nourished mother •Cow milk (Thiamine is sensitive to pasteurization and heat) •Unpolished grains (Polishing removes thiamine rich aleurone layer) •Eggs •Organ meats •Legumes Parboiling of rice retains Thiamine and other vitamins

7. Deficiency Thiamine deficiency results in Beriberi At risk groups : groups with diets based on polished rice and severely malnourished. Three forms of beriberi : ▪︎ Dry beriberi ▪︎ Wet beriberi ▪︎ Infantile beriberi

8. Clinical manifestations of beriberi • Dry beriberi : peripheral neuritis, paralysis of lower limbs, loss of deep tendon reflexes, muscle wasting, loss of position sense • Wet beriberi : congestive cardiac failure and pulmonary edema • Infantile beriberi : cardiomegaly, cyanosis, dyspepsia and aphonia (paralysis of laryngeal nerve)

9. WERNICKE ENCEPHALOPATHY: ~ occurs in infants and children with severe deficiency ~ TRIAD : Mental state changes Ocular signs Ataxia ~ Thalamus and periventricular gray matter show hemorrhagic lesions

10. Diagnosis ⊙ 24 hours urinary thiamine excretion - less than 15 μg /day (Normal excretion is 40 to 100 μg /day in children) ⊙ Response of red cell transketolase to addition of TPP over 25% increase - severe deficiency 15 to 25% increase - mild deficiency (Normally there is less than 15% increase in response) ⊙ Serum lactate and pyruvate levels - raised

11. Treatment ▪In children with mild beriberi - Thiamine 5 mg/day orally ▪In︎ severely ill children- Thiamine 10 mg BD intravenously ▪In children with fulminant heart disease - high doses of Thiamine + treatment of congestive heart failure