Pituitary
ApoplexyThisis a condition where there is acute onset
of neck stiffness, severe headaches, possible vomiting, fever and visual disturbances.
The underlying pathology is bleeding into the pituitary gland or more commonly
a pituitary gland tumor with erosion of blood vessels and a sudden bleed. Similar
hormone deficiencies as described might also be found, but the symptoms are much
more rapid. Diagnostic Tests: If there is a visual
field defect, this needs to be documented by visual field tests through an eye
specialist. Skull X-rays of the base of the skull might show an enlargement of
the "sella turcica", a name that means literally "Turkish saddle".
This is a pocket in the bone that looks (with a a bit of fantasy) like a saddle
and accommodates the pituitary gland. Further details can be obtained through
a high-resolution MRI or CT scan. In some university centers positron emission
tomography is also used. In cases where a vascular lesion is suspected such as
in the case of an aneurysm, cerebral angiography can be ordered where a dye is
injected and picked up on X-rays as the dye travels through the pituitary gland.
Hormone-wise I have explained earlier in this chapter what tests need to be done.
I shall repeat some of these tests here with links where appropriate. 1.
TSH function is determined by thyroid function tests for hypothyroidism
and hyperthyroidism. 2.
ACTH secretion is determined by adrenal gland function tests, either testing for
insufficiency or hyperfunction
of the adrenal glands. 3. Prolactin levels are determined by immunoassay
and at the same time the gonadotropins are often low (with panhypopituitarism).
4. GH levels are usually not tested in adults. However, in children with
dwarfism GH testing can be done with
a radioimmunoassay. A more readily available indirect test is the IGF-1 test,
which when normal rules out a GH deficiency. 5. GnRH
stimulation test: FSH and LH levels are most useful when they are
low in postmenopausal women who do not take estrogen, as this would establish
the presence of panhypopituitarism due to insufficient gonadotropin production.
The synthetic hypothalamic hormone GnRH can be given in these cases, which will
show no response in true primary hypopituitarism, but will show a response in
men with Kallman syndrome or other forms of secondary hypopituitarism. 6.
Hypothalamic releasing hormone stimulation test: Apart from the GnRH stimulation
test just mentioned, other tests can also be used to distinguish between primary
and secondary hypopituitarism. For instance, the CRH
stimulation test will establish whether or not a low ACTH level originates
from the pituitary gland (primary hypopituitarism) or from a defect in the hypothalamus
(secondary hypopituitarism such as with a meningioma or ependymoma). Other such
tests are the TRH
stimulation test to test TSH function or the GHRH
stimulation test to test for GH function.
| How to investigate
a hormone deficiency: | | The
principles of investigating for a hormone deficiency are such that a thorough
history and physical examination is done by the family physician or endocrinologist
and the whole person is being scrutinized for clues that may tell the physician
something about the hidden hormone dysbalance. Often this implies that the hormones
in the higher hormone centers or the hormones in the target hormone glands must
also be analyzed to identify the cause of the disease. |
Finally, in the case of deficiency of mineralocorticoids (aldosterone)
or the antidiuretic hormone (ADH) electrolytes and other blood tests need to be
evaluated as well. Treatment: It depends on the
hormone deficiency of the pituitary gland, which has been determined with the
above mentioned tests. Whatever hormone is missing must either be replaced, if
this is possible. Or else, if this is not possible, the target gland hormone must
be replaced. For instance, if only ACTH production is affected, then cortisol
and mineralocorticoids are low in the adrenal glands and have to be replaced as
described under Addison's disease,
as it is not feasible to replace ACTH. TSH deficiency is treated as described
under hypothyroidism with thyroid
hormone replacement. Gonadotropin deficiency is treated as described under treatment
for hypogonadism. GH deficiency is not treated for the adult, but
is used in selective cases by the endocrinologist as described under dwarfism.
Most of all it is absolutely essential not to overlook a case of a tumor in the
hypothalamus, the pituitary gland or any vascular abnormality such as an aneurysm
that could be prevented from rupturing. A neurosurgical consultation on an emergency
basis is needed here. As described under panhypopituitarism
a specialist will combine hormone replacement therapy with surgical treatment
of the tumor. With a small prolactinoma, which is a prolactin secreting adenoma
in the anterior lobe of the pituitary, the endocrinologist is often using bromocriptine
to suppress milk secretion by the breast glands. However, the larger prolactinomas
(> 2cm or >0.8") require either radiation or surgical excision. With
larger tumors, particularly the ones that affect visual fields, pituitary gland
surgery is done to remove the tumor through one of the sinus cavities with an
endoscopic procedure (transsphenoidal approach). This requires a special multidisciplinary
neurosurgical unit where neurologist, endocrinologist and neurosurgeon work together
as a team.
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