Read about addison’s disease
Hyponatremia (low blood sodium levels), due to the kidney’s inability to excrete free water in the absence of sufficient cortisol, and also the effect of Corticotropin-releasing hormone to stimulate secretion of ADH. That hyponatremia occurs even in secondary adrenal insufficiency (i.e. due to pituitary disease), in which aldosterone deficiency is not a feature, underscores the fact that hyponatremia in addison’s disease is not due to lack of aldosterone.
Like many other hormones, cortisol is regulated by the brain’s hypothalamus and the pituitary gland, a bean-sized organ at the base of the brain. First, the hypothalamus sends “releasing hormones” to the pituitary gland. The pituitary responds by secreting hormones that regulate growth and thyroid and adrenal function, and sex hormones such as estrogen and testosterone. One of the pituitary’s main functions is to secrete ACTH (adrenocorticotropin), a hormone that stimulates the adrenal glands.