HYPOPITUITARISM (underactivity of the pituitary gland)

The pituitary gland is a pea-sized endocrine gland (an "endocrine" gland is one that secretes "hormones", chemicals that circulate in the blood and affect other organs) situated in the head below the front part of the brain. It has important functions in the control of other endocrine glands, indeed it has been called "the conductor of the endocrine orchestra". The pituitary has two lobes, anterior and posterior, each of which secretes hormones. The posterior lobe is chiefly involved with the control of water balance through a hormone called ADH (antidiuretic hormone) and is only rarely involved in disease (see diabetes insipidus). The anterior lobe secretes several hormones of major importance including growth hormone (GH, which, as the name implies, is important in controlling growth), thyroid stimulating hormone (TSH, which drives the thyroid gland in the neck to produce thyroxine), adrenocorticotrophic hormone (ACTH, which drives the adrenal glands in the abdomen to produce steroids, especially hydrocortisone), and, at puberty, gonadotrophins (FSH and LH, which control sexual development and function).

Causes

Underactivity of the pituitary gland may result from several different causes. There may be a "congenital" (present at birth) abnormality in the formation of the gland or a congenital tumour (a "craniopharyngioma") in the region above the gland. Various diseases may damage the gland or the function may be disturbed by a head injury or as a side effect of treatment with radiotherapy to the head which may be needed for the treatment of leukaemia and some related conditions.

Diagnosis.

Diagnosis depends on the measurement of pituitary hormones in the blood either in the resting state or after stimulation tests to show more clearly the capacity of the gland. Scanning of the head, usually with an MR (magnetic resonance) scan can show the structure of the gland well.

Treatment.

Treatment consists of replacement either of the missing pituitary hormones themselves or of the hormones produced by the target glands. The most important of these hormones are hydrocortisone from the adrenal glands, which is important in maintaining the blood sugar and protecting against stress, and thyroxine, from the thyroid gland, which is involved in maintaining the rate of many biochemical processes. Growth hormone may have to be replaced in children before and during puberty to achieve adequate growth. Sex hormones, testosterone in boys and oestrogen in girls, may be needed to induce puberty in hypopituitary children and to maintain sexual development in adults.

Treatment Plan.

.........................................................'s current treatment regimen is as follows: Hydrocortisone ................mg (milligrams) each morning, ..........................mg each evening (this dose has to be increased to cover physical stress, such as an illness or injury, see the sheet on steroid replacement)

Thyroxine .........................mcg (micrograms) in the morning.

Growth hormone...............units.............................by subcutaneous injection each evening Testosterone ....................................................................

or

Oestrogen ........................................................................

Outlook.

With replacement of the missing hormones, people with hypopituitarism can live a full life with normal health and strength. To achieve fertility, special hormone treatment is usually needed.