8.3.1　Pituitarism

A pituitary adenoma（tumor）usually increases secretion of growth hormone or adrenocorticotropic hormone（ACTH）.Less commonly，a tumor affects the secretion of prolactin.An excess of growth hormone in children causes gigantism.In adults，it causes acromegaly，characterized by enlargement of the hands，feet，jaw，and facial features.Treatment is by surgery to remove the tumor（adenomectomy）or by drugs to reduce the level of growth hormone in the blood.Excess ACTH overstimulates the adrenal cortex，resulting in Cushing disease.Increased prolactin causes milk secretion，or galactorrhea，in both males and females.Radiographic studies in cases of pituitary adenoma usually show enlargement of the bony structure in the skull（sella turcica）that contains the pituitary.

Hypofunction of the pituitary caused by tumor or interruption of blood supply to the gland may involve a single hormone but usually affects all functions，a condition referred to as panhypopituitarism.The widespread effects of this condition include dwarfism（from lack of growth hormone），lack of sexual development and sexual function，fatigue，and weakness.A specific lack of ADH from the posterior pituitary results in diabetes insipidus，in which the kidneys have a decreased ability to conserve water.Symptoms include polyuria（elimination of large amounts of urine）and polydipsia（excessive thirst）.Diabetes insipidus should not be confused with diabetes mellitus.The two diseases share the symptoms of polyuria and polydipsia but have entirely different causes.Diabetes mellitus is the more common disorder，and when the term diabetes is used alone，it generally refers to diabetes mellitus.

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Task 3　Define the meaning of each medical term given below.