Assessment of Thiamin Nutritional Status

The impairment of pyruvate dehydrogenase in thiamin deficiency (Section 

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Nutritional status assessment for thiamine is generally carried out by assaying the total thiamine in whole blood or erythrocytes, or by measuring the activity of erythrocyte transketolase before and after incubation with exogenous thiamine pyrophosphate. The latter serves as the sensitive index of thiamine nutritional status (Brin 1980). In addition to the enzymatic test, a measure of urinary thiamine in relation to dietary intake has been the basis for balance studies to assess the adequacy of intake. When thiamine excretion is low, a larger portion of the test dose is retained, indicating a tissue s need for thiamine. A high excretion indicates tissue saturation. In the deficient state, excretion drops to zero. Plasma pyruvate and lactate concentrations have also been used to assess thiamine status. 

A small amount of thiamin is excreted in the urine unchanged, accounting for about 3% of a test dose, together with small amounts of thiamin monophosphate and thiamin diphosphate. As discussed in Section 6.5.1, this can be used to assess thiamin nutritional status. One of the major excretory products is thiochrome cyclization to thiochrome is the basis of the normal method of determining thiamin so, most reports of thiamin excretion are actually of thiamin plus thiochrome. In addition, small amounts of thiamin disulfide, formed by the oxidation of thiamin thiol, are also excreted. 

The increase in plasma lactate and pyruvate after a test dose of glucose was used historically as a means of assessing thiamin nutritional status (Section 6.5). 

When the alcoholic first presents for treatment, his/her nutritional status should be fully assessed. Vitamin supplementation should always be a component of this treatment. In the emergency room setting, the alcoholic patient usually receives intravenous fluids containing magnesium, thiamine, and multivitamin supplements. The yellow-colored fluid is commonly called a banana bag or rally pack. A daily... 

Thiamine, or vitamin Bi, is a water-soluble compound which is rapidly broken down by moist heat in neutral or alkaline solutions into its constituent pyrimidine and thiazole rings. The ready destructability of thiamine is important in human nutrition, since much may be lost in the preparation of food. Some of the biochemical methods used in evaluating thiamine nutrition are based on reactions with the thiazole and pyrimidine portions of the thiamine molecule. The thiochrome method is widely used in assaying biological materials for thiamine, while determination of the urinary excretion of pyramine (a pyrimidine-like compound) has been used to assist in assessment of nutritional status. 

For enzymes that have a tightly bound cofactor, such as thiamin diphosphate (and also riboflavin derivatives see section 11.7 and vitamin B, section 11.9), the extent to which red blood cells can compete with other tissues for the vitamin-derived coenzyme provides a sensitive means of assessing nutritional status. Tissue contains ... 

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