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

Table 1

Baseline characteristics of the 11,833 samples.

Parameter (units)	Median (IQR or %)
Patient age (years)	56 (41, 68)
Female gender ()	58.8% (57.9, 59.7) (6961)
Holotranscobalamin (pmol/L)	64 (45, 93)
B12 (pmol/L)	292 (222, 393)
MMA (nmol/L)	175 (137, 234)
Hcy (μmol/L)	12.1 (9.7, 15.3)
HoloTC/B12 % (%)	21.1% (15.7, 27.9)
Haptocorrin-bound B12 (pmol/L)	226 (164, 312)
4cB12	0.24 (-0.11, 0.58)
Elevated B12 () ()	0.9% (0.75, 1.1) (107)
B12 adequacy (4cB12: -0.5 to 1.5) ()	90.4% (89.9, 91) (10701)
Low B12 (4cB12: -1.5 to -0.51) ()	8.2% (7.7, 8.7) (967)
Possible B12 deficiency (4cB12: -1.51 to -2.5) ()	0.43% (0.33,0.57) (51)
Probable B12 deficiency () ()	0.06% (0.03, 0.12) (7)

IQR: interquartile range for continuous variables; CI: confidence interval for proportion. Both are given in brackets.