Table 3 Basal and stimulated copeptin concentrations of patients with central diabetes insipidus and primary polydipsia upon the hypertonic saline infusion test.

From: Validity of different copeptin assays in the differential diagnosis of the polyuria-polydipsia syndrome

 

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

  1. 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.
  2. *Statistically significant.