One study reported a mean AQP2 of 176.3 fmol/mg Cr in healthy individuals and mean levels of 685.0 fmol/mg Cr in individuals with SIADH.28 Another study found levels averaging 569.9 ± 162.7 fmol/mg Cr in individuals with SIADH.17 Several studies have examined U-AQP2 excretion in patients with SIADH due to various factors. The gene discussed is AQP2; the disease is inappropriate ADH syndrome.