Pituitary apoplexy is a stroke of the pituitary gland with 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.
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 (thanks to www.emedicinehealth.com for this link): 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 (thanks to www.emedicinehealth.com for this link) 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 (thanks to thyroid.about.com for this link) to test TSH function or the GHRH stimulation test (thanks to www.nlm.nih.gov/medlineplus for this link) 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. We are lucky nowadays that most hormones are readily analyzed by lab tests and the sex hormones can also be analyzed more accurately by saliva hormones tests, which parallel more the tissue levels than the blood tests.
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.
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 (thanks to emedicine.medscape.com for this link) 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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