TABLE 2.
Comparison of holotranscobalamin (holoTC) and total vitamin B-12 for diagnosis of vitamin B-12 deficiency1
| Total no. of subjects (total no. of subjects with vitamin B-12 deficiency) | Nationality | Age | Limits for MMA (tHcy) | AUC for holoTC | AUC for vitamin B-12 | Reference |
| y | μmol/L | |||||
| 806 (24) | Danish | >18 | >0.75 (>15) | 0.90 | 0.85 | 32 |
| 1651 (70) | English | >65 | >0.75 | 0.87 | 0.79 | 56 |
| 1651 (129) | English | >65 | >0.45 | 0.80 | 0.73 | 56 |
| 533 (71) | German | 18–98 | >0.40 | — | 0.72 | 59 |
| 125 (16) | German | 18–98 | >0.40 | 0.66 | — | 59 |
| 759 (174) | German | 8–92 | >0.30 | 0.71 | 0.60 | 58 |
| 204 (68) | German, Dutch | 21–73 | >0.27 | 0.88 | 0.84 | 57 |
1
The limits for MMA and tHcy indicate the cutoffs that were used to classify the patients as vitamin B-12 deficient. The researchers assessed the results with the use of receiver operating curves. An area under the curve (AUC) of 1.0 indicates a perfect test, and an AUC of 0.5 indicates a useless test. MMA, methylmalonic acid; tHcy, homocysteine.