Diagnostic Accuracy of Holotranscobalamin, Vitamin B12, Methylmalonic Acid, and Homocysteine in Detecting B12 Deficiency in a Large, Mixed Patient Population

Table 3

Marker cutoffs for detecting possible or probable B12 deficiency (4cB12≤ -1.5) with a sensitivity or specificity of 99% at a given specificity and sensitivity, as well as the optimum decision point.

Marker	Cutoff 99% sensitivity	Corresponding specificity (%)	Cutoff 99% specificity	Corresponding sensitivity (%)	Optimum decision point	Corresponding sensitivity/specificity (%)
HoloTC (pmol/L)	<56.5	60	<19	77.6	<27	93.1/96
B12 (pmol/L)	<320	41.6	<115	56.9	<167	94.8/92.3
MMA (nmol/L)	>158	39.1	>723	72.4	>466	94.8/96.4
Hcy (μmol/L)	>6.2	3	>34	32.8	>16,4	87.9/80.9