Pituitary Disorders Quiz

See Hypopituitarism. Option A is correct because antidiuretic hormone (ADH) comes from the posterior pituitary, which is normally spared when a pituitary adenoma causes hypopituitarism. A pituitary adenoma (a benign tumour) usually presses on the glandular tissue of the anterior pituitary, producing a progressive loss of its hormones, with growth hormone and the gonadotrophins (LH and FSH) often lost first. ADH and oxytocin are made in the hypothalamus and merely released from the posterior pituitary, so they are only lost if the tumour also damages the hypothalamus. ADH deficiency can come from a hypothalamic tumour, a pituitary tumour that has grown up into the hypothalamus, cranial radiotherapy, pituitary surgery, autoimmune infiltration or infections such as meningitis. It causes cranial diabetes insipidus: large volumes of dilute urine, dehydration and thirst. A memory aid: the anterior lobe is the factory, so tumour pressure on it hurts production; the posterior lobe is only a warehouse for hormones made elsewhere.

• Hormone: antidiuretic hormone (ADH) comes from the posterior pituitary, which is normally spared.
• Cause: an adenoma presses on the anterior pituitary, and growth hormone and the gonadotrophins are often lost first.
• Origin: ADH is made in the hypothalamus, so it is lost only if the tumour also damages the hypothalamus.
• If lost: ADH deficiency causes cranial diabetes insipidus, with large volumes of dilute urine, dehydration and thirst.