The type II pattern is the second most common osmoregulatory defect and has been termed the ΓÇÿreset osmostatΓÇÖ. Patients with the type II defect continue to regulate water excretion about a lowered plasma osmolality. This pattern of vasopressin secretion is observed in patients with neoplasms, chest disease, and nervous disorders. The pathogenesis of the pattern remains unknown, but interruption of the afferent limb of the baroregulatory reflex arc that normally inhibits vasopressin secretion is one possible mechanism.
