Table 5.
Serum MMA and vitamin B-12 median, central 95% reference intervals, and corresponding samples sizes by age group in US persons ≥20 y of age, NHANES 2011–20141
| Serum B-12, pmol/L | Serum MMA, nmol/L | ||||
|---|---|---|---|---|---|
| Age group | Overall2 | Overall2 | Normal renal function3 | B-12 replete4 | B-12 replete & normal renal function5 |
| Median (95% CI) | |||||
| All | 378 (372, 384) | 144 (141, 147) | 138 (134, 141) | 135 (132, 139) | 130 (127, 133) |
| Age, y | |||||
| 20–39 | 373 (364, 381) | 126 (123, 128) | 125 (123, 128) | 121 (118, 124) | 120 (118, 124) |
| 40–59 | 365 (357, 378) | 144 (140, 148) | 142 (138, 146) | 133 (129, 139) | 133 (128, 138) |
| 60–69 | 398 (375, 420) | 157 (150, 164) | 151 (143, 158) | 149 (143, 154) | 143 (134, 149) |
| ≥70 | 416 (401, 428) | 191 (186, 197) | 168 (162, 175) | 180 (175, 184) | 161 (151, 167) |
| 2.5th – 97.5th Percentile | |||||
| All | 158 – 1,140 | 70.6 – 451 | 69.6 – 391 | 67.9 – 328 | 67.2 – 281 |
| Age, y | |||||
| 20–39 | 167 – 840 | 65.1 – 304 | 65.5 – 297 | 63.3 – 256 | 63.5 – 254 |
| 40–59 | 160 – 1,150 | 72.8 – 442 | 73.0 – 403 | 70.5 – 324 | 70.5 – 293 |
| 60–69 | 152 – 1,530 | 77.0 – 497 | 76.4 – 430 | 74.0 – 327 | 72.4 – 281 |
| ≥70 | 137 – 1,720 | 92.5 – 758 | 85.9 – 571 | 90.1 – 447 | 84.3 – 317 |
| Sample size | |||||
| All | 10,020 | 10,020 | 7,718 | 7,109 | 5,481 |
| Age, y | |||||
| 20–39 | 3,375 | 3,373 | 3,038 | 2,420 | 2,178 |
| 40–59 | 3,431 | 3,429 | 2,835 | 2,393 | 1,988 |
| 60–69 | 1,666 | 1,667 | 1,173 | 1,170 | 824 |
| ≥70 | 1,548 | 1,551 | 672 | 1,126 | 491 |
Values are weighted percentiles and sample sizes. While NHANES 2013–2014 collected samples from participants ≥19 y of age, we only included data for participants ≥20 y of age. Serum vitamin B-12 was measured by Roche E-170 immunoassay and serum MMA by HPLC-MS/MS. B-12, vitamin B-12; CKD, chronic kidney disease; MMA, methylmalonic acid.
Pregnant and lactating women were excluded.
Pregnant and lactating women, participants with CKD stage 1–5, and participants with missing or incomplete CKD stage information were excluded.
Pregnant and lactating women, participants with serum B-12 <300 pmol/L, and participants with missing serum vitamin B-12 data were excluded.
Pregnant and lactating women, participants with CKD stage 1–5 and serum B-12 <300 pmol/L, and participants with missing/incomplete CKD stage information and/or missing serum vitamin B-12 data were excluded.