Table 6.
Comparison of serum VB12/MMA and plasma tHCY levels in patients with or without VB12 deficiency.
| Number (% Total Group) | |||
|---|---|---|---|
| VB12 Deficiency | |||
| Yes | No | p-Value | |
| Characteristic | (n = 37) | (n = 138) | |
| Serum VB12 levels (pg/ML) | |||
| Mean ± SEM | 254 ± 22 | 433 ± 15 | <0.0001 |
| (Range) | (71–665) | (150–999) | |
| # with VB12 level < 200 pg/mL (a) | 16 (43%) | 2 (1.4%) | <0.0001 |
| # with VB12 level 200–350 pg/mL (b) | 14 (38%) | 53 (38%) | 0.99 |
| Serum MMA levels (uM) | |||
| Mean ± SEM | 0.46 ± 0.03 | 0.19 ± 0.01 | <0.0001 |
| (Range) | (0.14–0.83) | (0.06–0.42) | |
| # with MMA level > 0.26 (uM) (c) | 31 (84%) | 22(16%) | <0.0001 |
| # with MMA level > 0.37 (uM) (c) | 30 (81%) | 2 (1.4%) | <0.0001 |
| Plasma tHCY levels (uM) | |||
| Mean ± SEM | 15.3 ± 1.1 | 8.8 ± 0.3 | <0.0001 |
| (Range) | (7.0–41.0) | (4.0–47.0) | |
| # with tHCY level > 13 uM (d) | 18 (49%) | 4 (2.9%) | <0.0001 |
| # with tHCY level > 15 uM (d) | 14 (39%) | 0 (0%) | <0.0001 |
Abbreviations: See legends in Table 1, Table 2, Table 3, Table 4 and Table 5. (a) Numerous studies have proposed a serum VB12 level of <200 pg/mL for diagnosing VB12-deficient patients [112,113,114,115,118,120,233,235]. (b) Serum VB12 levels over the range of 200–350 pg/mL have been reported to represent a low-level range that could suggest VB12 deficiency [115,116,118]. (c) Several studies propose classifying those with serum MMA > 0.37 uM as VB12-deficient patients [115,116,117,118] and a few recommend using a serum MMA level of >0.26 uM [116,235,236,237]. These recommendations are only for patients with normal renal function [113,116,236,238]. (d) Various studies have proposed either a plasma tHCY level of >13 uM [113,115,234] or >15 uM [112,114,115,235] as the upper limit of normal.