Table 2.
Currently reported and calculated reference intervals for vitamins and related ratios
| Test/Ratio | RIreported | n | LRL | URL |
|---|---|---|---|---|
| Retinol [Vitamin A] (μmol/L) | 1.6–2.5 | 137 | 1.1 (1.1–1.3) | 2.8 (2.7–2.9) |
| Alpha-Tocopherol [alpha-T, Vitamin E] (μmol/L) | 18.6–46.2 | 139 | 18.9 (17.6–21.4) | 42.2 (41.6–43.2) |
| Alpha-T/CH ratio (μmol/mmol) | NA | 138 | 5.2 (4.9–5.3) | 8.9 (8.6–9.3) |
| Alpha-T/TL ratio (μmol/mmol) | NA | 137 | 4.5 (4.2–4.6) | 7.4 (7.3–7.5) |
| Thiamine pyrophosphate [TPP, Vitamin B1] (nmol/L) | 78–144 | 141 | 85.9 (78.1–95.8) | 181.6 (173.3–187.8) |
| TPP/Hb ratio (ng/g) | NA | 135 | 246.2 (237.4–269.7) | 561.1 (535.0–588.8) |
| Pyridoxal 5'-phosphate [PLP, Vitamin B6] (nmol/L) | 51–183 | 138 | 57.0 (48.2–60.9) | 165.7 (155.2–176.6) |
Numbers in parentheses indicate 90% confidence intervals of each limit. RIreported, reference intervals currently reported in our laboratory; LRL, lower reference limit; URL, upper reference limit; NA, not applicable.