Table 1: Traditional and evidence-based vitamin B12 deficiency reference values.

Assessment	Traditional assessment cutoffs	Evidence-based assessment cutoffs
Serum B12	< 148 pmol/L (< 200 pg/ml)	< 300 pmol/L (< 405 pg/ml)
Homocysteine	> 15 µmol/L	≥ 10 µmol/L
Holo TC II	< 35 pmol/L	< 50 pmol/L
Serum MMA	> 260 nmol/L or > 271 nmol/L	> 260 nmol/L or > 271 nmol/L
Urinary MMA	> 4.3 µmol/L	> 4.0 µmol/L
Urinary MMA/creatinine	> 4.8 mmol/L creatinine	> 3.5 mmol/L creatinine
MCV	> 98 µm^3/cell	> 98 µm^3/cell