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 sheet on 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. |
