Investigations
1st investigations to order
whole blood thiamine pyrophosphate
erythrocyte thiamine pyrophosphate
ABG
Test
Vitamin B1 deficiency is associated with lactic acidosis and a raised lactate, but their presence is not diagnostic and their absence does not exclude the deficiency.
Result
anion gap metabolic acidosis
lactate
Test
Lactate levels are typically an indicator of anaerobic metabolism due to poor tissue perfusion, and should be measured in response to an unexplained raised anion gap metabolic acidosis found on ABG measurement.
While vitamin B1 deficiency is associated with lactic acidosis and a raised lactate, their presence is not diagnostic and their absence does not exclude the deficiency.[44]
Result
raised
thyroid function tests
Test
All patients presenting in high-output cardiac failure should have urgent thyroid function tests to rule out thyrotoxicosis.[60]
Result
raised free thyroxine (T4)/triiodothyronine (T3) and suppressed thyroid-stimulating hormone (TSH) in thyrotoxicosis
Investigations to consider
MRI brain
Test
MRI of the brain is useful to support a diagnosis of Wernicke's encephalopathy.[13][61]
In Wenicke’s encephalopathy, sensitivity is 53% and specificity is 93%.[13][62]
Result
bilateral and symmetrical lesions in the thalamus, mammillary bodies, tectal plate, and periaqueductal region on T2-weighted imaging or fluid-attenuated inversion recovery (FLAIR) sequence
echocardiography
Test
May be useful for diagnosis of wet beriberi and to help guide management.[7]
Result
high-output cardiac failure
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