Tests
1st tests to order
erythrocyte thiamine pyrophosphate
Test
Before starting thiamine-replacement therapy, a blood sample should be taken for erythrocyte thiamine pyrophosphate. Erythrocyte thiamine phosphate is a good indicator of the body stores of thiamine, as thiamine depletes at the same rate in erythrocytes as in other tissues.[49]
As this test will take several days, treatment should not be delayed while awaiting the result.
The result can be used to retrospectively confirm thiamine deficiency.
Result
reduced
arterial blood gas
Test
While vitamin B1 deficiency is associated with lactic acidosis and an elevated lactate, their presence is not diagnostic and their absence does not exclude the deficiency.
Result
raised anion gap metabolic acidosis
lactate
Test
Lactate is elevated in any condition causing an increase in anaerobic respiration and should be measured in response to an unexplained raised anion gap metabolic acidosis found on arterial blood gas measurement.
While vitamin B1 deficiency is associated with lactic acidosis and an elevated lactate, their presence is not diagnostic and their absence does not exclude the deficiency.
Result
elevated
thyroid function tests
Test
All patients presenting in high-output cardiac failure should have thyroid function tests urgently checked to rule out thyrotoxicosis.
Result
elevated free T4/T3 and suppressed TSH in thyrotoxicosis
Tests to consider
MRI brain
Test
MRI of the brain can detect changes associated with Wernicke encephalopathy, but these are not entirely specific to the condition. With a sensitivity of 53% and a specificity of 93% for Wernicke encephalopathy, this investigation is most useful to rule out the diagnosis.[51]
Result
bilateral increased T2 signal in the paraventricular regions of the thalamus, hypothalamus, mamillary bodies, periaqueductal region, fourth ventricle floor, and midline cerebellum
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