Table 1.
Results on Passing-and-Bablok-fit analyses for phenylalanine and tyrosine concentrations in LH plasma, EDTA plasma, and capillary DBS
| Phenylalaninea | Lithium heparin (LH) plasma | EDTA plasma | Capillary blood spot | |||||||
| Median (range) | intercept | slope | R | intercept | slope | R | intercept | slope | R | |
| LH plasma | 326 (20–1574) | |||||||||
| EDTA plasma | 321 (23–1707) | −2.1 | 1.10* | 0.991 | ||||||
| Capillary DBS | 325.5 (26.8–1580) | 2.8 | 1.00 | 0.993 | 9.7 | 0.92* | 0.978 | |||
| Venous DBS | 309 (25.9–1490) | 7.5 | 0.98 | 0.990 | 6.1 | 0.93* | 0.981 | 0.7 | 1.01 | 0.984 |
| LH DBS | 297 (23.5–1610) | 6.5 | 0.96* | 0.996 | 4.7 | 0.88* | 0.985 | −0.7 | 0.98 | 0.991 |
| EDTA DBS | 311 (26.4–1550) | 6.3 | 0.96* | 0.995 | 5.9 | 0.89* | 0.984 | −0.6 | 1.00 | 0.992 |
| Tyrosinea | LH plasma | EDTA plasma | Capillary blood spot | |||||||
| Median (range) | intercept | slope | R | intercept | slope | R | intercept | slope | R | |
| LH plasma | 61 (25–804) | |||||||||
| EDTA plasma | 72 (29–912) | 0.0 | 1.12* | 0.982 | ||||||
| Capillary DBS | 68.25 (24.2–881) | 6.4* | 1.02 | 0.930 | 6.8* | 0.93* | 0.903 | |||
| Venous DBS | 67 (26.8–871) | 3.3 | 1.04 | 0.934 | 4.6 | 0.92* | 0.934 | −0.9 | 0.99 | 0.934 |
| LH DBS | 64.1 (23.1–845) | 1.8 | 1.05 | 0.951 | −0.1 | 0.96 | 0.937 | −4.1 | 1.01 | 0.964 |
| EDTA DBS | 70.9 (24.1–793) | 4.5 | 0.98 | 0.959 | 4.7 | 0.91 | 0.934 | −1.3 | 0.97 | 0.959 |
aThe methods in the upper row (x) were compared to parameters in the left column (y), where y = intercept + slope * x. Results with an asterix represent significant differences with p < 0.05 (intercept significantly different from 0; slope significantly different from 1)