Table 3.
Basal and stimulated copeptin concentrations of patients with central diabetes insipidus and primary polydipsia upon the hypertonic saline infusion test.
| KRYPTOR | LIA | ELISA | p-value | |
|---|---|---|---|---|
| Central diabetes insipidus (n = 20) | ||||
| Basal plasma copeptin (pmol/l) | 1.6 [1.4, 1.9] | 0.8 [0.4, 2.0] | 18.2 [8.8, 23.1] | < 0.001* |
| KRYPTOR vs LIA | 1.6 [1.4, 1.9] | 0.8 [0.4, 2.0] | – | 0.52 |
| KRYPTOR vs ELISA | 1.6 [1.4, 1.9] | – | 18.2 [8.8, 23.1] | < 0.001* |
| LIA vs ELISA | – | 0.8 [0.4, 2.0] | 18.2 [8.8, 23.1] | < 0.001* |
| Stimulated plasma copeptin (pmol/l) | 1.7 [1.3, 2.6] | 1.4 [0.4, 2.3] | 17.2 [12.8, 28.6] | < 0.001* |
| KRYPTOR vs LIA | 1.7 [1.3, 2.6] | 1.4 [0.4, 2.3] | – | 1 |
| KRYPTOR vs ELISA | 1.7 [1.3, 2.6] | – | 17.2 [12.8, 28.6] | < 0.001* |
| LIA vs ELISA | – | 1.4 [0.4, 2.3] | 17.2 [12.8, 28.6] | < 0.001* |
| Primary polydipsia (n = 20) | ||||
| Basal plasma copeptin (pmol/l) | 4.1 [2.6, 5.6] | 3.4 [1.7, 5.9] | 14.7 [11.1, 27.8] | < 0.001* |
| KRYPTOR vs LIA | 4.1 [2.6, 5.6] | 3.4 [1.7, 5.9] | 1 | |
| KRYPTOR vs ELISA | 4.1 [2.6, 5.6] | 14.7 [11.1, 27.8] | < 0.001* | |
| LIA vs ELISA | 3.4 [1.7, 5.9] | 14.7 [11.1, 27.8] | 0.001* | |
| Stimulated plasma copeptin (pmol/l) | 20.4 [13.0, 27.8] | 18.0 [11.5, 26.4] | 23.0 [15.7, 34.6] | 0.350 |
| KRYPTOR vs LIA | 20.4 [13.0, 27.8] | 18.0 [11.5, 26.4] | – | 1 |
| KRYPTOR vs ELISA | 20.4 [13.0, 27.8] | – | 23.0 [15.7, 34.6] | 0.34 |
| LIA vs ELISA | – | 18.0 [11.5, 26.4] | 23.0 [15.7, 34.6] | 0.34 |
Copeptin was measured in duplicates with the KRYPTOR, the LIA and the ELISA. Results are indicated as median [Interquartile range]. Three-group comparison was done using the Friedman Test. Posthoc two group comparison was done using the paired Wilcoxon Sign Rank Test with Bonferroni p-value adjustment.
*Statistically significant.