5 things that might surprise you about GHK Cu 1 Your body already makes it. GHK Cu is a naturally occurring copper peptide found in plasma, saliva, and urinebut levels decline as we age. Do I Have Wilson Disease? Wilson Disease Association Progress toward improved Wilson's disease drug Cold Spring Harbor Laboratory EASL Clinical Practice Guidelines: Wilson's disease ScienceDirect In the Beginning: Neonatal Screening and Management of Wilson Disease AASLD Diagnosis Wilson Disease Association