Table 2.

Summary of SIAD subtype definition in response to 3% NaCl infusion

SIAD Subtype	Definition
A	Plasma copeptin consistently >38 pmol/L with a copeptin slope <95% CI for that of healthy persons (i.e., <0.66 pmol/L/mOsM/kg H2O)
B	Any plasma copeptin concentration with a positive copeptin slope >0.25 pmol/L/mOsM/kg H2O, but a low osmotic threshold <95% CI for that of healthy persons (i.e., <281 mOsM/kg H2O)
C	Plasma copeptin concentration between 2 and 38 pmol/L with a copeptin slope between −0.25 and 0.25 pmol/L/mOsM/kg H2O
D	Plasma copeptin concentration consistently <2 pmol/L regardless of the copeptin slope
E	Any plasma copeptin concentration with a copeptin slope <−0.25 pmol/L/mOsM/kg H2O