Table 2 Median copeptin concentrations of all three patients’ cohorts at any measured timepoint using the three different copeptin assays.

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

 

KRYPTOR

LIA

ELISA

p-value

Healthy volunteers (n = 30)

Plasma copeptin (pmol/l)

14.7 [8.8, 20.6]

10.1 [7.1, 14.0]

48.1 [35.4, 59.0]

 < 0.001*

 KRYPTOR vs LIA

14.7 [8.8, 20.6]

10.1 [7.1, 14.0]

–

 < 0.001*

 KRYPTOR vs ELISA

14.7 [8.8, 20.6]

–

48.1 [35.4, 59.0]

 < 0.001*

 LIA vs ELISA

–

10.1 [7.1, 14.0]

48.1 [35.4, 59.0]

 < 0.001*

Severely ill patients (n = 40)

Plasma copeptin (pmol/l)

74.3 [50.5, 135.1]

70.9 [47.8, 108.6]

80.1 [70.2, 125.0]

0.025*

 KRYPTOR vs LIA

74.3 [50.5, 135.1]

70.9 [47.8, 108.6]

–

0.023*

 KRYPTOR vs ELISA

74.3 [50.5, 135.1]

–

80.1 [70.2, 125.0]

1

 LIA vs ELISA

–

70.9 [47.8, 108.6]

80.1 [70.2, 125.0]

0.71

Polyuria-polydipsia patients (n = 80)

Plasma copeptin (pmol/l)

2.9 [1.6, 10.3]

2.8 [0.7, 9.7]

17.9 [11.3, 28.9]

 < 0.001*

 KRYPTOR vs LIA

2.9 [1.6, 10.3]

2.8 [0.7, 9.7]

 

0.70

 KRYPTOR vs ELISA

2.9 [1.6, 10.3]

 

17.9 [11.3, 28.9]

 < 0.001*

 LIA vs ELISA

 

2.8 [0.7, 9.7]

17.9 [11.3, 28.9]

 < 0.001*

  1. Copeptin was measured in duplicates with the KRYPTOR, the LIA and the ELISA. Continuous variables are expressed 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.
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