Histidine load test, folate status

Folate status can be assessed by the measurement of serum or red blood ceil folate levels, by the histidine load test, and by hematological methods. 

Although the FIGLU test depends on folate nutritional status, the metabolism of histidine wUl also be impaired and a positive result obtained, in vitamin B12 deficiency, because of the secondary deficiency of folate (Section 10.3.4.1). About 60% of vitamin Bi2-deficient subjects show increased FIGLU excretion after a histidine load. 

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