Thiamine and Beri-Beri: A Summary

• Vitamin B1 is Thiamine.

(TCA = TriCarboxylic Acid cycle aka Kreb's cycle ; LDH = Lactate Dehydrogenase ; PDH = Pyruvate Dehydrogenase ; TPP = Thiamine PyroPhosphate)

• Peripheral neuropathy in dry beri-beri is symmetric, sensorimotor, distal > proximal and non-inflammatory demyelinating type.

• Wernicke's syndrome is reversible early while Korsakoff psychosis is reversible in only 20% cases.

• Wernicke-Korsakoff syndrome has typical damage to dorsomedial nucleus of thalamus and mamillary bodies.

• Clinical manifestations of B1 deficiency is worsened by glucose load! As seen in pathophysiology, excess of glucose with relative or absolute deficiency of B1 - as TPP - causes diversion from the preferred PDH pathway (linked to TCA), to the LDH pathway causing life-threatening lactic acidosis. Hence, in a patient with alcohol intoxication/ chronic alcoholism a B1+glucose cocktail is given as they usually are deficient in B1.

Biochemistry pearl: Other co-factors in PDH pathway alongside TPP are Lipoic acid, Coenzyme A, FAD(H) and NAD(H).

DIAGNOSIS:

Clinical diagnosis with confirmatory lab work - that includes:

• Diagnostic - Blood or RBC transketolase activity and increase after intramuscular B1 administration
• Supportive - Blood thiamine, pyruvate and lactate levels

MANAGEMENT:

You give what the patient lacks. An acceptable regimen is:

Injection B1 100 mg intramuscular for 1 week

followed by

Tablet B1 10 mg once-daily per-oral for 1 month.

Let me know if anything needs clarification. Happy studying!

--Ashish Singh.