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

Table 2

Marker cutoffs for detecting subclinical B12 deficiency (4cB12≤ -0.5 and >-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)	<73	44.1	<25	27.5	<45	85.7/81.2
B12 (pmol/L)	<351	36.7	<142	28.2	<229	86.1/77.7
MMA (nmol/L)	>152	37.8	>480	29.3	>245	81.8/83.4
Hcy (μmol/L)	>8	12.6	>29	11.5	>15	67.7/76.7