My vasopressin is low and I'm taking a pituitary/ hypothalamus glandular called "Cytozyme PT/HPT" from Biotics. This is my suggestion for anyone with HPA axis dysfunction (along w adrenal support). But also, if a person is low in vasopressin, he/she might need to supplement w potassium, but I would only do this if the person has symptoms of low potassium (muscle cramps, excessive thirst, frequent urination)--- not to be confused w symptoms of low sodium (dizziness, excessive thirst, frequent urination).
Originally, when I was talking to Dr Neville about pituitary glandulars, he said that he wasn't sure if it made it through the blood brain barrier, but after using it, I'm sure that it does, because I definitely notice a difference.