Comparative study of vitamin B12 and holotranscobalamin or active B12 as a marker for vitamin B12 deficiency at Dr George Mukhari Hospital

Abstract

Abstract

Aim: This study was undertaken to compare the diagnostic sensitivity and specificity of

total vitamin B 12 analyses to active B 12 (holoTC) analyses in a population of patients

attending the Dr George Mukhari Hospital in Pretoria.

Methods: Routine serum folate, full blood count (FBC), thyroid function test,

homocysteine, serum total vitamin B 12 and active B 12 analyses were performed on 30

samples.

Results: Serum folate was determined in all patients and 96% of the patients had a

normal folate value. When looking at the FBC results it is important to note that three

times as many males as females presented with anemia (36% versus 16%). Thyroid

function tests were normal in 90% of patients. When the total vitamin B 12 test was

preformed only 10% of patients tested positive for vitamin B 12 deficiency, in contrast to

the active B12 analyses where 16% of patients tested positive for vitamin B12 deficiency.

Both tests had a diagnostic sensitivity of 50%. The diagnostic specificity for total vitamin

B12 was 93% in comparison with the 86% obtained by the active B12 analyses; when

homocysteine was used as the true marker for vitamin B12 deficiency.

Conclusion: Diagnostic sensitivity was the same and the total vitamin B12 test's

specificity was better in comparison to the active B 12 analyses. Thus the active B 12

assay cannot be recommended for routine use, since it has no benefit.