Thiamine (Vitamin B1) deficiency causes Wernicke's encephalopathy, which is characterized by the classic triad of mental confusion, oculomotor dysfunction, and gait ataxia. Punctate hemorrhages around the third and fourth ventricles are characteristic. Thiamine deficiency is most often associated with chronic alcoholism. Other conditions associated with thiamine deficency include anorexia nervosa, prolonged intravenous feeding without proper supplementation, prolonged fasting or starvation, dialysis, and gastrointestinal surgery. Wernicke's encephalopathy is a well known complication of bariatric surgery and typically occurs 4 to 12 weeks following surgery.
Laboratory and neuroimaging studies are helpful, but the biggest barrier to diagnosis is a low index of suspicion. Whenever Wernicke's encephalopathy is considered in the differential diagnosis, immediate thiamine replacement should be given. Treatment should not be delayed for diagnostic testing.
Thiamine diphosphate is the active form of thiamine. It is present predominantly in erythrocytes, with very little occurring in plasma. Measurement of thiamine diphosphate in whole blood by liquid chromatography and mass spectrometry is the preferred method for determining nutritional status.
Reference range is 70-180 nmol/L.
Specimen requirement is a lavender top (EDTA) tube of blood. Specimen should be transferred to an amber tube to protect from light and immediately frozen.