Evaluation of a commercial radioassay for the simultaneous estimation of vitamin B12 and folate, with subsequent derivation of the normal reference range.

A commercial assay kit method for the simultaneous estimation of vitamin B12 and folate concentrations has been evaluated. Values derived for folate by a microbiological assay and vitamin B12 by a verified radioassay showed good correlation with the investigated method. The clinical sensitivity of the assay for detecting deficient concentrations of vitamin B12 and folate was comparable to that of the non-commercial methods and other more definitive clinical procedures. Establishment of reference ranges, based on accepted statistical criteria, are discussed and such ranges are contrasted with those proposed by the manufacturer. The kit method is time and labour saving compared with the non-commercial methods.