There are different causes for pituitary hypofunction, which all lead to decreased release of pituitary hormones. As a result of this decreased release of pituitary hormones, the endocrine target organs have decreased function. In this picture, three important causes of hypopituitarism are mentioned. (1) A disorder at the level of the hypothalamus (e.g. a tumor): the releasing hormones are not secreted or cannot reach the endocrine cells in the anterior pituitary. (2) A disorder in the vascularisation
of the pituitary caused by an infarction or trauma. (3) A disorder at the level of the endocrine cells of the pituitary mostly as a result of benign tumors. Substitution of all target hormones (thyroxine, glucocorticoids, growth hormone, androgens and estrogens) is necessary, when there is complete hypofunction.
Check out these drugs under their specific headings (hypothalamic-pituitary-thyroid axis, hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-gonadal axis).
I. Hypothalamic and pituitary diseases affect either single or multiple hormonal systems. II. Pituitary hormone deficiency is characterised by decreased pituitary hormone levels and increased hormone levels secreted by the target organs.
Extra info: In a hypothalamic or pituitary disorder one or more hormones of the pituitary can be involved and as a result one or more hormonal systems can be affected. In hypopituitarism, the levels of one or more pituitary hormones are decreased. As a result of the decreased pituitary hormone secretion, the hormone levels secreted by the target organs are also decreased.