Table 3 FT4 and FT3 reference intervals derived using different laboratory instruments in children with TSH concentration 0.5–5.0 mIU/L.
Statistical Parameters | FT4, pmol/L | FT3, pmol/L | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
DxI 800 | Centaur | Vitros 5600 | Cobas | Architect | DxI 800 | Centaur | Vitros 5600 | Cobas | Architect | |
TSH < 0.5 mIU/L, n excluded | 11 | 11 | 12 | 11 | 12 | 11 | 11 | 12 | 11 | 12 |
TSH > 5.0 mIU/L, n excluded | 5 | 5 | 4 | 6 | 3 | 5 | 5 | 4 | 6 | 3 |
Outlier by Reeds test | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Final n | 44 | 44 | 44 | 43 | 45 | 44 | 44 | 44 | 43 | 45 |
Normality by Shapiro-Wilk test | Accept | Accept | Accept | Accept | Accept | Reject | Accept | Accept | Accept | Accept |
Transformation | None | None | None | None | None | Logarithmic | None | None | None | None |
Minimum | 10.1 | 12.8 | 11.0 | 14.6 | 11.2 | 4.7 | 4.2 | 4.9 | 4.2 | 3.6 |
Maximum | 19.0 | 23.2 | 25.0 | 27.0 | 20.1 | 9.1 | 8.5 | 9.2 | 8.4 | 7.0 |
Mean | 13.9 | 17.6 | 17.7 | 20.5 | 15.7 | 6.4 | 5.8 | 6.7 | 5.9 | 5.0 |
Median | 14.0 | 18.0 | 18.0 | 20.6 | 15.6 | 6.1 | 5.9 | 6.8 | 5.9 | 5.0 |
SD | 2.0 | 2.3 | 3.1 | 2.8 | 1.9 | NA | 0.9 | 1.1 | 1.0 | 0.7 |
Reference intervals (normal) | ||||||||||
Lower limit (2.5th percentile) | 10.0 | 13.1 | 11.5 | 15.1 | 11.8 | 4.6 | 4.1 | 4.6 | 4.0 | 3.6 |
90% CI | 9.1 to 10.8 | 12.1 to 14.1 | 10.2 to 12.9 | 13.8 to 16.3 | 11.0 to 12.7 | 4.3 to 5.0 | 3.7 to 4.5 | 4.1 to 5.0 | 3.6 to 4.4 | 3.4 to 3.9 |
Upper limit (97.5th percentile) | 17.8 | 22.1 | 23.8 | 25.9 | 19.5 | 8.8 | 7.6 | 8.8 | 7.7 | 6.4 |
90% CI | 17.0 to 18.7 | 21.1 to 23.0 | 22.4 to 25.1 | 24.7 to 27.1 | 18.6 to 20.3 | 8.2 to 9.5 | 7.2 to 8.0 | 8.3 to 9.3 | 7.3 to 8.1 | 6.1 to 6.7 |
Robust method (CLSI C28-A3) | ||||||||||
Lower limit | 9.8 | 12.8 | 11.3 | 14.9 | 11.7 | 4.4 | 4.0 | 4.4 | 3.8 | 3.5 |
90% CI | 8.9 to 10.8 | 11.9 to 14.0 | 9.9 to 13.0 | 13.7 to 16.2 | 10.9 to 12.6 | 4.1 to 4.8 | 3.6 to 4.5 | 4.0 to 5.0 | 3.4 to 4.3 | 3.2 to 3.9 |
Upper limit | 17.9 | 22.3 | 24.1 | 26.2 | 19.7 | 8.9 | 7.6 | 8.9 | 7.7 | 6.5 |
90% CI | 17.1 to 18.8 | 21.3 to 23.2 | 22.9 to 25.4 | 25.0 to 27.3 | 18.8 to 20.5 | 8.1 to 9.6 | 7.2 to 8.0 | 8.4 to 9.3 | 7.3 to 8.2 | 6.2 to 6.8 |
