Investigations

1st investigations to order

whole blood thiamine pyrophosphate

Test
Result
Test

Guidelines recommend measurement of thiamine pyrophosphate levels in whole blood or erythrocytes.[1][13]​​ 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

erythrocyte thiamine pyrophosphate

Test
Result
Test

Guidelines recommend measurement of thiamine pyrophosphate levels in whole blood or erythrocytes.[1][13]​​ 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

ABG

Test
Result
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
Result
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
Result
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
Result
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
Result
Test

May be useful for diagnosis of wet beriberi and to help guide management.[7]

Result

high-output cardiac failure

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