When in a water deprivation test S-ADH (antidiuretic hormone) decreases between eight a'clock and eleven, does it mean diabetes insipidus? Is 0.7 normal ADH? I have periods of polyuria and dehydration. During such periods my serum osmolality is near the upper reference limit and Na+ slightly over the upper limit. Can partial diabetes insipidus be periodic. I have also primary hyperparathyroidism.