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beriberi, muscle wasting is obvious. In infants, cardiac failure may occur rather suddenly (McCormick and Greene, 1994). Severe thiamin deficiency in industrialized countries is likely to be related to heavy alcohol consumption with limited food consumption, as was noted for at least four of five Welsh cases reported by Anderson and colleagues (1985). In those cases renal and cardiovascular complications were life threatening.

SELECTION OF INDICATORS FOR ESTIMATING THE REQUIREMENT FOR THIAMIN

Biochemical changes in thiamin status occur well before the appearance of overt signs of deficiency. Thiamin status can be assessed by determining erythrocyte transketolase activity, by measuring the concentration of thiamin and its phosphorylated esters in blood or serum components using high-performance liquid chromatography, or by measuring urinary thiamin excretion under basal conditions or after thiamin loading. Commonly used reference values indicating marginal deficiency for these indicators are given in Table 4-1. Other methods have also been reported and are covered briefly below.

No currently available indicator, by itself, provides an adequate basis on which to estimate the thiamin requirement.

Urinary Thiamin Excretion

The urinary excretion of thiamin is the indicator that has been used most widely in metabolic studies of thiamin requirements and

TABLE 4-1 Reference Values for the Primary Measures of Thiamin Status

Indicator

Marginal Deficiency

Deficiency

Erythrocyte transketolase activitya

1.20–1.25

> 1.25

Erythrocyte thiamin (nmol/L)a

70–90

< 70

Thiamin pyrophosphate effect (%)b

15–24

≥ 25

Urinary thiamina

 

 

(nmol [µg]/g creatinine)

90–220 (27–66)

< 27

(nmol [µg]/d)

133–333 (40–100)

< 40

a Schrijver (1991).

b Stimulated value, expressed as a multiple of the basal value. Also termed the activity coefficient. Brin (1970).



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