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Pituitary incidentalomas are pituitary tumors that are characterized as an incidental finding. They are often discovered by computed tomography (CT) or magnetic resonance imaging (MRI), performed in the evaluation of unrelated medical conditions such as suspected head trauma, in cancer staging or in the evaluation of nonspecific symptoms such as dizziness and headache. It is not uncommon for them to be discovered at autopsy. In a meta-analysis, adenomas were found in an average of 16.7% in postmortem studies, with most being microadenomas (<10mm); macrodenomas accounted for only 0.16% to 0.2% of the decedents. While non-secreting, noninvasive pituitary microadenomas are generally considered to be literally as well as clinically benign, there are to date scant studies of low quality to support this assertion.
It has been recommended in the current Clinical Practice Guidelines (2011) by the Endocrine Society - a professional, international medical organization in the field of endocrinology and metabolism - that all patients with pituitary incidentalomas undergo a complete medical history and physical examination, laboratory evaluations to screen for hormone hypersecretion and for hypopituitarism. If the lesion is in close proximity to the optic nerves or optic chiasm, a visual field examination should be performed. For those with incidentalomas which do not require surgical removal, follow up clinical assessments and neuroimaging should be performed as well follow-up visual field examinations for incidentalomas that abut or compress the optic nerve and chiasm and follow-up endocrine testing for macroincidentalomas.
Unlike tumors of the posterior Pituitary, Pituitary adenomas are classified as endocrine tumors (not brain tumors). Pituitary adenomas are classified based upon anatomical, histological and functional criteria.
- Anatomically pituitary tumors are classified by their size based on radiological findings; either microadenomas (less than <10 mm) or macroadenomas (equal or greater than ≥10 mm).
- Histological classification utilizes an immunohistological characterization of the tumors in terms of their hormone production. Historically they were classed as either basophilic, acidophilic, or chromophobic on the basis of whether or not they took up the tinctorial stains hematoxylin and eosin. This classification has fallen into disuse, in favor of a classification based on what type of hormone is secreted by the tumor. Approximately 20-25% of adenomas do not secrete any readily identifiable active hormones ('non-functioning tumors') yet they are still sometimes referred to as 'chromophobic'.
- Functional classification is based upon the tumors endocrine activity as determined by serum hormone levels and pituitary tissue cellular hormone secretion detected via immunohistochemical staining. The "Percentage of hormone production cases" values are the fractions of adenomas producing each related hormone of each tumor type as compared to all cases of pituitary tumors, and does not directly correlate to the percentages of each tumor type because of smaller or greater incidences of absence of secretion of the expected hormone. Thus, nonsecretive adenomas may be either "null cell adenomas" or a more specific adenoma that, however, remains nonsecretive.
Hyperparathyroidism is confirmed by blood tests such as calcium and PTH levels. A specific test for parathyroid adenoma is sestamibi parathyroid scintigraphy, the sestamibi scan. This nuclear imaging technique reveals the presence and location of pathological parathyroid tissue.
A physician's response to detecting an adenoma in a patient will vary according to the type and location of the adenoma among other factors. Different adenomas will grow at different rates, but typically physicians can anticipate the rates of growth because some types of common adenomas progress similarly in most patients. Two common responses are removing the adenoma with surgery and then monitoring the patient according to established guidelines.
One common example of treatment is the response recommended by specialty professional organizations upon removing adenomatous polyps from a patient. In the common case of removing one or two of these polyps from the colon from a patient with no particular risk factors for cancer, thereafter the best practice is to resume surveillance colonoscopy after 5–10 years rather than repeating it more frequently than the standard recommendation.
Surgery is the only cure for parathyroid adenomas. It is successful about 95% of the time. Parathyroidectomy is the removal of the affected gland(s). The standard of treatment of primary hyperparathyroidism was formerly a surgical technique called bilateral neck exploration, in which the neck was opened on both sides, the parathyroids were identified, and the affected tissue was removed. By the 1980s, unilateral exploration became more common. Parathyroidectomy can now be performed in a minimally invasive fashion, mainly because imaging techniques can pinpoint the location of the tissue. Minimally invasive techniques include smaller open procedures, radio-guided and video-assisted procedures, and totally endoscopic surgery.
Before surgery is attempted, the affected glandular tissue must be located. Though the parathyroid glands are usually located on the back of the thyroid, their position is variable. Some people have one or more parathyroid glands elsewhere in the neck anatomy or in the chest. About 10% of parathyroid adenomas are ectopic, located not along the back of the thyroid but elsewhere in the body, sometimes in the mediastinum of the chest. This can make them difficult to locate, so various imaging techniques are used, such as the sestamibi scan, single-photon emission computed tomography (SPECT), ultrasound, MRI, and CT scans. sometimes parathyroid adenomas can be ablated by ethanol injection, guided by ultrasound.
A doctor will test for prolactin blood levels in women with unexplained milk secretion (galactorrhea) or irregular menses or infertility, and in men with impaired sexual function and, in rare cases, milk secretion. If prolactin is high, a doctor will test thyroid function and ask first about other conditions and medications known to raise prolactin secretion. The doctor will also request a magnetic resonance imaging (MRI), which is the most sensitive test for detecting pituitary tumors and determining their size. MRI scans may be repeated periodically to assess tumor progression and the effects of therapy. Computed Tomography (CT scan) also gives an image of the pituitary, but it is less sensitive than the MRI.
In addition to assessing the size of the pituitary tumor, doctors also look for damage to surrounding tissues, and perform tests to assess whether production of other pituitary hormones is normal. Depending on the size of the tumor, the doctor may request an eye exam with measurement of visual fields.
Fine Needle Aspiration Cytology (FNAC) is a cheap, simple, and safe method in obtaining cytological specimens for diagnosis by using a needle and a syringe. The "Bethesda System for Reporting Thyroid Cytopathology" is the system used to report whether the thyroid cytological specimen is benign or malignant. It can be divided into six categories:
Repeated FNAC is recommended for Category I, followed by clinical follow-up in Category II, repeat FNAC for Category III, and lobectomy for Category IV, near total-thyroidectomy/lobectomy for Category V, and near total thyroidectomy for Category VI. The risk of malignancy in a malignant FNAC report is 93.7% while for suspicious FNAC report, it is 18.9%.
If acromegaly is suspected, medical imaging and medical laboratory investigations are generally used together to confirm or rule out the presence of this condition.
IGF1 provides the most sensitive lab test for the diagnosis of acromegaly, and a GH suppression test following an oral glucose load, which is a very specific lab test, will confirm the diagnosis following a positive screening test for IGF1. A single value of the GH is not useful in view of its pulsatality (levels in the blood vary greatly even in healthy individuals). GH levels taken 2 hours after a 75- or 100-gram glucose tolerance test are helpful in the diagnosis: GH levels are suppressed below 1 μg/l in normal people, and levels higher than this cutoff are confirmatory of acromegaly.
Other pituitary hormones must be assessed to address the secretory effects of the tumor, as well as the mass effect of the tumor on the normal pituitary gland. They include thyroid stimulating hormone (TSH), gonadotropic hormones (FSH, LH), adrenocorticotropic hormone, and prolactin.
An MRI of the brain focusing on the sella turcica after gadolinium administration allows for clear delineation of the pituitary and the hypothalamus and the location of the tumor. A number of other overgrowth syndromes can result in similar problems.
Ultrasound imaging is useful as the first-line, non-invasive investigation in determining the size, texture, position, and vascularity of a nodule, accessing lymph nodes metastasis in the neck, and for guiding fine needle aspiration cytology (FNAC) or biopsy. High frequency transducer (7–12 MHz) is used to scan the thyroid nodule, while taking cross-sectional and longitudinal sections during scan. Suspicious findings in a nodule are hypoechoic, ill-defined margins, absence of peripheral halo or irregular margin, fine, punctate microcalcifications, presence of solid nodule, high levels of irregular blood flow within the nodule or "taller-than-wide sign" (anterior-posterior diameter is greater than transverse diameter of a nodule). Features of benign lesion are: hyperechoic, having coarse, dysmorphic or curvilinear calcifications, comet tail artifact (reflection of a highly calcified object), absence of blood flow in the nodule, and presence of cystic (fluid-filled) nodule. However, the presence of solitary or multiple nodules is not a good predictor of malignancy. Malignancy is only diagnosed when ultrasound findings and FNAC report are suggestive of malignancy. Another imaging modality, which is ultrasound elastography, is also useful in diagnosing thyroid malignancy especially for follicular thyroid cancer. However, it is limited by the presence of adequate amount of normal tissue around the lesion, calcified shell around a nodule, cystic nodules, coalescent nodules.
For the diagnosis of hyperpituitarism it depends on the cell type(s) affected, clinical manifestations of hormone excess may include, gigantism or acromegaly, which can be identified by clinical and radiographic results. Cushing's disease diagnosis is done with a physical examination, laboratory tests and X rays of the pituitary glands (to locate tumors) For prolactinoma, diagnosis comes in the form of the measurement of serum prolactin levels and x-ray of pituitary gland.
If one of these tests shows a deficiency of hormones produced by the pituitary, magnetic resonance imaging (MRI) scan of the pituitary is the first step in identifying an underlying cause. MRI may show various tumors and may assist in delineating other causes. Tumors smaller than 1 cm are referred to as "microadenomas", and larger lesions are called "macroadenomas". Computed tomography with radiocontrast may be used if MRI is not available. Formal visual field testing by perimetry is recommended, as this would show evidence of optic nerve compression by a tumor.
Other tests that may assist in the diagnosis of hypopituitarism, especially if no tumor is found on the MRI scan, are ferritin (elevated in hemochromatosis), angiotensin converting enzyme (ACE) levels (often elevated in sarcoidosis), and human chorionic gonadotropin (often elevated in tumor of germ cell origin). If a genetic cause is suspected, genetic testing may be performed.
It is recommended that magnetic resonance imaging (MRI) scan of the pituitary gland is performed if the diagnosis is suspected; this has a sensitivity of over 90% for detecting pituitary apoplexy; it may demonstrate infarction (tissue damage due to a decreased blood supply) or hemorrhage. Different MRI sequences can be used to establish when the apoplexy occurred, and the predominant form of damage (hemorrhage or infarction). If MRI is not suitable (e.g. due to claustrophobia or the presence of metal-containing implants), a computed tomography (CT) scan may demonstrate abnormalities in the pituitary gland, although it is less reliable. Many pituitary tumors (25%) are found to have areas of hemorrhagic infarction on MRI scans, but apoplexy is not said to exist unless it is accompanied by symptoms.
In some instances, lumbar puncture may be required if there is a suspicion that the symptoms might be caused by other problems (meningitis or subarachnoid hemorrhage). This is the examination of the cerebrospinal fluid that envelops the brain and the spinal cord; the sample is obtained with a needle that is passed under local anesthetic into the spine. In pituitary apoplexy the results are typically normal, although abnormalities may be detected if blood from the pituitary has entered the subarachnoid space. If there is remaining doubt about the possibility of subarachnoid hemorrhage (SAH), a magnetic resonance angiogram (MRI with a contrast agent) may be required to identify aneurysms of the brain blood vessels, the most common cause of SAH.
Professional guidelines recommend that if pituitary apoplexy is suspected or confirmed, the minimal blood tests performed should include a complete blood count, urea (a measure of renal function, usually performed together with creatinine), electrolytes (sodium and potassium), liver function tests, routine coagulation testing, and a hormonal panel including IGF-1, growth hormone, prolactin, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, thyroid hormone, and either testosterone in men or estradiol in women.
Visual field testing is recommended as soon as possible after diagnosis, as it quantifies the severity of any optic nerve involvement, and may be required to decide on surgical treatment.
The diagnosis of hypopituitarism is made on blood tests. Two types of blood tests are used to confirm the presence of a hormone deficiency: basal levels, where blood samples are taken–usually in the morning–without any form of stimulation, and dynamic tests, where blood tests are taken after the injection of a stimulating substance. Measurement of ACTH and growth hormone usually requires dynamic testing, whereas the other hormones (LH/FSH, prolactin, TSH) can typically be tested with basal levels. There is no adequate direct test for ADH levels, but ADH deficiency can be confirmed indirectly; oxytocin levels are not routinely measured.
Generally, the finding of a combination of a low pituitary hormone together with a low hormone from the effector gland is indicative of hypopituitarism. Occasionally, the pituitary hormone may be normal but the effector gland hormone decreased; in this case, the pituitary is not responding appropriately to effector hormone changes, and the combination of findings is still suggestive of hypopituitarism.
Diagnosis is made first by diagnosing Cushing's syndrome, which can be difficult to do clinically since the most characteristic symptoms only occur in a minority of patients. Some of the biochemical diagnostic tests used include salivary and blood serum cortisol testing, 24-hour urinary free cortisol (UFC) testing, the dexamethasone suppression test (DST), and bilateral inferior petrosal sinus sampling (BIPSS). No single test is perfect and multiple tests should always be used to achieve a proper diagnosis. Diagnosing Cushing's disease is a multidisciplinary process involving doctors, endocrinologists, radiologists, surgeons, and chemical pathologists.
Once Cushing's syndrome has been diagnosed, the first step towards finding the cause is measuring plasma corticotropin concentrations. A concentration consistently below 1.1 pmol/L is classified as corticotropin-independent and does not lead to a diagnosis of Cushing's disease. In such cases, the next step is adrenal imaging with CT. If plasma corticotropin concentrations are consistently above 3.3 pmol/L, then corticotropin-dependent Cushing's syndrome is most likely. Any intermediate values need to be cautiously interpreted and a corticotropin-releasing hormone (CRH) test is advised in order to confirm corticotropin dependency. If corticotropin-dependent Cushing's syndrome is determined then the next step is to distinguish between Cushing's disease and ectopic corticotropin syndrome. This is done via a combination of techniques including CRH, high-dose DST, BIPSS, and pituitary MRI.
Two dexamethasone suppression tests (DSTs) are generally used, the overnight and 48-h DSTs. For both tests, a plasma cortisol level above 50 nmol/L is indicative of Cushing's disease. However, 3-8% of patients with Cushing's disease will test negative due to a retention of dexamethasone suppression abilities. For non-Cushing or healthy patients, the false-positive rate is 30%. The 48-h DST is advantageous since it is more specific and can be done by outpatients upon proper instruction. In the high-dose 48-h DST, 2 mg of dexamethasone is given every 6 hours for 48 hours or a single dose of 8 mg is given. This test is not needed if the 48-h low-dose DST has shown suppression of cortisol by over 30%. These tests are based on the glucocorticoid sensitivity of pituitary adenomas compared to non-pituitary tumors.
Administration of corticotropin releasing hormone (CRH) can differentiate this condition from ectopic ACTH secretion. In a patient with Cushing's disease, the tumor cells will be stimulated to release corticotropin and elevated plasma corticotropin levels will be detected. This rarely occurs with ectopic corticotropin syndrome and thus is quite useful for distinguishing between the two conditions. If ectopic, the plasma ACTH and cortisol levels should remain unchanged; if this is pituitary related, levels of both would rise. The CRH test uses recombinant human or bovine-sequence CRH, which is administered via a 100μg intravenous bolus dose. The sensitivity of the CRH test for detecting Cushing's disease is 93% when plasma levels are measured after fifteen and thirty minutes. However, this test is used only as a last resort due to its high cost and complexity.
A CT or MRI of the pituitary may also show the ACTH secreting tumor if present. However, in 40% of Cushing's disease patients MRI is unable to detect a tumor. In one study of 261 patients with confirmed pituitary Cushing's disease, only 48% of pituitary lesions were identified using MRI prior to surgery. The average size of tumor, both those that were identified on MRI and those that were only discovered during surgery, was 6 mm.
A more accurate but invasive test used to differentiate pituitary from ectopic or adrenal Cushing's syndrome is inferior petrosal sinus sampling. A corticotropin gradient sample via BIPSS is required to confirm diagnosis when pituitary MRI imaging and biochemical diagnostic tests have been inconclusive. A basal central:peripheral ratio of over 3:1 when CRH is administered is indicative of Cushing’s disease. This test has been the gold standard for distinguishing between Cushing's disease and ectopic corticotropin syndrome. The BIPSS has a sensitivity and specificity of 94% for Cushing's disease but it is usually used as a last resort due to its invasiveness, rare but serious complications, and the expertise required to perform it.
Another diagnostic test used is the urinary free cortisol (UFC) test, which measures the excess cortisol excreted by the kidneys into the urine. Results of 4x higher cortisol levels than normal are likely to be Cushing's disease. This test should be repeated three times in order to exclude any normally occurring periods of hypercortisolism. The UFC test has a specificity of 81% and thus has a high rate of false-positives that are due to pseudo-Cushing states, sleep apnea, polycystic ovary syndrome, familial glucocorticoid resistance, and hyperthyroidism.
The late-night or midnight salivary cortisol test has been gaining support due to its ease of collection and stability at room temperature, therefore it can be assigned to outpatients. The test measures free circulating cortisol and has both a sensitivity and specificity of 95-98%. This test is especially useful for diagnosing children.
The first step in diagnosing a thyroid neoplasm is a physical exam of the neck area. If any abnormalities exist, a doctor needs to be consulted. A family doctor may conduct blood tests, an ultrasound, and nuclear scan as steps to a diagnosis. The results from these tests are then read by an endocrinologist who will determine what problems the thyroid has.
Hyperthyroidism and hypothyroidism are two conditions that often arise from an abnormally functioning thyroid gland. These occur when the thyroid is producing too much or too little thyroid hormone respectively.
Thyroid nodules are a major presentation of thyroid neoplasms, and are diagnosed by ultrasound guided fine needle aspiration (USG/FNA) or frequently by thyroidectomy (surgical removal and subsequent histological examination). FNA is the most cost-effective and accurate method of obtaining a biopsy sample. As thyroid cancer can take up iodine, radioactive iodine is commonly used to treat thyroid carcinomas, followed by TSH suppression by high-dose thyroxine therapy.
Nodules are of particular concern when they are found in those under the age of 20. The presentation of benign nodules at this age is less likely, and thus the potential for malignancy is far greater.
Common diagnostic techniques include:
- MRIs
- CAT scans
- blood samples.
Blood samples are assessed for the absence or presence of aldosterone and cortisol. Physical examinations are also useful in patients in order to examine vision, skin pigmentation, how the body replaces steroids, and the cranial nerves. Recent advancements in high-resolution MRIs allow for adenomas to be detected during the early stages of Nelson syndrome. Physical examination including height, weight, vital signs, blood pressure, eye examination, thyroid examination, abdominal examination, neurological examination, skin examination and pubertal staging needs to be assessed. Through blood pressure and pulse readings can indicate hypothyroidism and adrenal insufficiency. Hyper-pigmentation, hyporeflexia, and loss of vision can also indicate Nelson's syndrome when assessed together. Specifically for a child who might have Nelson's syndrome, the patient should be questioned about the symptoms of the disease, and well as symptoms of other diseases to narrow down which disease the patient presents with. The patient should be questioned about how often and to what degree headaches, visual disturbances, and symptoms associated with pituitary malfunction occur. Additionally, adrenal steroid replacement should be assessed, especially in children who have prior insufficiency associated wit
A recommend surveillance program for Multiple Endocrine Neoplasia Type 1 has been suggested by the International Guidelines for Diagnosis and Therapy of MEN syndromes group.
There are a few scans and tests that the physician can conduct in order to diagnose a person with craniopharyngioma. Your doctor may order a high-resolution magnetic resonance imaging (MRI) scan. This test is valuable because it allows the neuroradiologist to view the tumor from different angles.
In some cases, a powerful 3T (Tesla) MRI scanner can help define the location of critical brain structures affected by the tumor.The histologic pattern consists of nesting of squamous epithelium bordered by radially arranged cells. It is frequently accompanied by calcium deposition and may have a microscopic papillary architecture.A computed tomography (CT) scan is also a good diagnostic tool as it detects calcification in the tumor.
Two distinct types are recognized:
- Adamantinomatous craniopharyngiomas, which resemble ameloblastomas (the most common type of odontogenic tumor), are characterized by activating CTNNB1 mutations; and,
- Papillary craniopharyngiomas are characterized by BRAFv600E mutations.
In the adamantinomatous type, calcifications are visible on neuroimaging and are helpful in diagnosis.
The papillary type rarely calcifies. A vast majority of craniopharyngiomas in children are adamantiomatous whereas both subtypes are common in adults. Mixed type tumors also occur.
On macroscopic examination, craniopharyngiomas are cystic or partially cystic with solid areas. On light microscopy, the cysts are seen to be lined by stratified squamous epithelium. Keratin pearls may also be seen. The cysts are usually filled with a yellow, viscous fluid which is rich in cholesterol crystals. Of a long list of possible symptoms, the most common presentations include: headaches, growth failure, and bitemporal hemianopsia.
Craniopharyngiomas are usually successfully managed with a combination of adjuvant chemotherapy and neurosurgery. Recent research describes the rare occurrence of malignant transformations of these normally benign tumors. Malignant craniopharyngiomas can occur at any age, are slightly more common in females, and are usually of the adamantinomatous type.
The malignant transformations can take years to occur (although 1 in 5 of the diagnosed cases were de novo transformations), hence the need for lengthier follow up in patients diagnosed with the more common benign forms.
There was no link found between malignancy and initial chemo-radiotherapy treatment, and the overall survival rate was very poor with median survival being 6 months post diagnosis of malignancy.
A medical biopsy refers to the obtaining of a tissue sample for examination under the microscope or other testing, usually to distinguish cancer from noncancerous conditions. Thyroid tissue may be obtained for biopsy by fine needle aspiration (FNA) or by surgery.
Fine needle aspiration has the advantage of being a brief, safe, outpatient procedure that is safer and less expensive than surgery and does not leave a visible scar. Needle biopsies became widely used in the 1980s, but it was recognized that the accuracy of identification of cancer was good, but not perfect. The accuracy of the diagnosis depends on obtaining tissue from all of the suspicious areas of an abnormal thyroid gland. The reliability of fine needle aspiration is increased when sampling can be guided by ultrasound, and over the last 15 years, this has become the preferred method for thyroid biopsy in North America.
Treatment (for hyperpituitarism) in the case of prolactinoma consists of long-term medical management. Dopamine agonists are strong suppressors of PRL secretion and establish normal gonadal function. It also inhibits tumor cell replication (in some cases causes tumor shrinkage) Treatment for gigantism begins with establishing target goals for IGF-1, transsphenoidal surgery (somatostatin receptor ligands- preoperatively) and postoperative imaging assessment. For Cushing's disease there is surgery to extract the tumor; after surgery, the gland may slowly start to work again, though not always.
Autoantibodies to the thyroid gland may be detected in various disease states. There are several anti-thyroid antibodies, including anti-thyroglobulin antibodies (TgAb), anti-microsomal/anti-thyroid peroxidase antibodies (TPOAb), and TSH receptor antibodies (TSHRAb).
- Elevated anti-thryoglobulin (TgAb) and anti-thyroid peroxidase antibodies (TPOAb) can be found in patients with Hashimoto's thyroiditis, the most common autoimmune type of hypothyroidism. TPOAb levels have also been found to be elevated in patients who present with subclinical hypothyroidism (where TSH is elevated, but free T4 is normal), and can help predict progression to overt hypothyroidism. The American Association Thyroid Association thus recommends measuring TPOAb levels when evaluating subclinical hypothyroidism or when trying to identify whether nodular thyroid disease is due to autoimmune thyroid disease.
- When the etiology of hyperthyroidism is not clear after initial clinical and biochemical evaluation, measurement of TSH receptor antibodies (TSHRAb) can help make the diagnosis. In Grave's disease, TSHRAb levels are elevated as they are responsible for activating the TSH receptor and causing increased thyroid hormone production.
Treatment of a thyroid nodule depends on many things including size of the nodule, age of the patient, the type of thyroid cancer, and whether or not it has spread to other tissues in the body.
If the nodule is benign, patients may receive thyroxine therapy to suppress thyroid-stimulating hormone and should be reevaluated in 6 months. However, if the benign nodule is inhibiting the patient's normal functions of life; such as breathing, speaking, or swallowing, the thyroid may need to be removed.
Sometimes only part of the thyroid is removed in an attempt to avoid causing hypothyroidism. There's still a risk of hypothyroidism though, as the remaining thyroid tissue may not be able to produce enough hormones in the long-run.
If the nodule is malignant or has indeterminate cytologic features, it may require surgery. A thyroidectomy is a medium risk surgery that can result complications if not performed correctly. Problems with the voice, nerve or muscular damage, or bleeding from a lacerated blood vessel are rare but serious complications that may occur. After removing the thyroid, the patient must be supplied with a replacement hormone for the rest of their life. This is commonly a daily oral medication prescribed by their endocrinologist.
Radioactive iodine-131 is used in patients with papillary or follicular thyroid cancer for ablation of residual thyroid tissue after surgery and for the treatment of thyroid cancer. Patients with medullary, anaplastic, and most Hurthle cell cancers do not benefit from this therapy. External irradiation may be used when the cancer is unresectable, when it recurs after resection, or to relieve pain from bone metastasis.
Pseudoacromegaly is a condition with the usual acromegaloid features, but without an increase in growth hormone and IGF-1. It is frequently associated with insulin resistance. Cases have been reported due to minoxidil at an unusually high dose. It can also be caused by a selective postreceptor defect of insulin signalling, leading to the impairment of metabolic, but preservation of mitogenic, signalling.
If a woman has one or more small prolactinoma, there is no reason that she cannot conceive and have a normal pregnancy after successful medical therapy. The pituitary enlarges and prolactin production increases during normal pregnancy in women without pituitary disorders. Women with prolactin-secreting tumors may experience further pituitary enlargement and must be closely monitored during pregnancy. However, damage to the pituitary or eye nerves occurs in less than one percent of pregnant women with prolactinoma. In women with large tumors, the risk of damage to the pituitary or eye nerves is greater, and some doctors consider it as high as 25%. If a woman has completed a successful pregnancy, the chances of her completing further successful pregnancies are extremely high.
A woman with a prolactinoma should discuss her plans to conceive with her physician, so she can be carefully evaluated prior to becoming pregnant. This evaluation will include a magnetic resonance imaging (MRI) scan to assess the size of the tumor and an eye examination with measurement of visual fields. As soon as a patient is pregnant, her doctor will usually advise that she stop taking bromocriptine or cabergoline, the common treatments for prolactinoma. Most endocrinologists see patients every two months throughout the pregnancy. The patient should consult her endocrinologist promptly if she develops symptoms — in particular, headaches, visual changes, nausea, vomiting, excessive thirst or urination, or extreme lethargy. Bromocriptine or cabergoline treatment may be renewed and additional treatment may be required if the patient develops symptoms from growth of the tumor during pregnancy.
At one time, oral contraceptives were thought to contribute to the development of prolactinomas. However, this is no longer thought to be true. Patients with prolactinoma treated with bromocriptine or cabergoline may also take oral contraceptives. Likewise, post-menopausal estrogen replacement is safe in patients with prolactinoma treated with medical therapy or surgery.