Name = Hypopituitarism
Caption = The pituitary gland on a plate from
Gray's Anatomy(1918). The anterior lobe is on the left, and the posterior lobe on the right, both in red.
DiseasesDB = 6522
ICD10 = ICD10|E|23|0|e|20, ICD10|E|89|3|e|70
ICD9 = ICD9|253.7
MedlinePlus = 000343
eMedicineSubj = emerg
eMedicineTopic = 277
eMedicine_mult = eMedicine2|med|1137 eMedicine2|ped|1130
MeshID = D007018
Hypopituitarism is the decreased ("hypo") secretion of one or more of the eight
hormones normally produced by the pituitary glandat the base of the brain. [DorlandsDict|four/000051775|Hypopituitarism] If there is decreased secretion of most pituitary hormones, the term panhypopituitarism ("pan" meaning "all") is used. [DorlandsDict|six/000077779|Panhypopituitarism]
The signs and symptoms of hypopituitarism vary, depending on which hormones are undersecreted and on the underlying cause of the abnormality. The diagnosis of hypopituitarism is made by
blood tests, but often specific scans and other investigations are needed to find the underlying cause, such as tumors of the pituitary, and the ideal treatment. Most hormones controlled by the secretions of the pituitary can be replaced by tablets or injections. Hypopituitarism is a rare disease, but may be significantly underdiagnosed in people with previous traumatic brain injury. The first description of the condition was made in 1914 by the German physician Dr Morris Simmonds.
igns and symptoms
The hormones of the pituitary have different actions in the body, and the symptoms of hypopituitarism therefore depend on which hormone is deficient. The symptoms may be subtle and are often initially attributed to other causes.cite journal |author=Schneider HJ, Aimaretti G, Kreitschmann-Andermahr I, Stalla GK, Ghigo E |title=Hypopituitarism |journal=Lancet |volume=369 |issue=9571 |pages=1461–70 |year=2007 |month=April |pmid=17467517 |doi=10.1016/S0140-6736(07)60673-4] cite journal |author=van Aken MO, Lamberts SW |title=Diagnosis and treatment of hypopituitarism: an update |journal=Pituitary |volume=8 |issue=3-4 |pages=183–91 |year=2005 |pmid=16508719 |doi=10.1007/s11102-006-6039-z] In most of the cases, three or more hormones are deficient.cite journal |author=Regal M, Páramo C, Sierra SM, Garcia-Mayor RV |title=Prevalence and incidence of hypopituitarism in an adult Caucasian population in northwestern Spain |journal=Clin. Endocrinol. (Oxf) |volume=55 |issue=6 |pages=735–40 |year=2001 |month=December |pmid=11895214 | doi=10.1046/j.1365-2265.2001.01406.x] The most common problem is insufficiency of
follicle-stimulating hormone(FSH) and/or luteinizing hormone(LH) leading to sex hormone abnormalities. Growth hormone deficiencyis more common in people with an underlying tumor than those with other causes.
Sometimes, there are additional symptoms that arise from the underlying cause; for instance, if the hypopituitarism is due to a growth hormone-producing tumor, there may be symptoms of
acromegaly(enlargement of the hands and feet, coarse facial features), and if the tumor extends to the optic nerveor optic chiasm, there may be visual field defects. Headaches may also accompany pituitary tumors, as well as pituitary apoplexy( strokeof the pituitary gland) and lymphocytic hypophysitis ( autoimmuneinflammation of the pituitary).cite journal |author=Prabhakar VK, Shalet SM |title=Aetiology, diagnosis, and management of hypopituitarism in adult life |journal=Postgrad Med J |volume=82 |issue=966 |pages=259–66 |year=2006 |month=April |pmid=16597813 |doi=10.1136/pgmj.2005.039768 |url=http://pmj.bmj.com/cgi/content/full/82/966/259]
Deficiency of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), together referred to as the
gonadotropins, leads to different symptoms in men and women. Women experience oligo- or amenorrhea (infrequent/light or absent menstrual periodsrespectively) and infertility. Men lose facial, scrotal and trunk hair, as well as suffering decreased muscle mass and anemia. Both sexes may experience a decrease in libidoand loss of sexual function, and have an increased risk of osteoporosis(bone fragility). Lack of LH/FSH in children is associated with delayed puberty. Growth hormone(GH) deficiency leads to a decrease in muscle mass, central obesity(increase in body fat around the waist) and impaired attention and memory. Children experience growth retardationand short stature. Adrenocorticotropic hormone(ACTH) deficiency leads to adrenal insufficiency, a lack of production of glucocorticoids such as cortisolby the adrenal gland. If the problem is chronic, symptoms consist of fatigue, weight loss, failure to thrive(in children), delayed puberty(in adolescents), hypoglycemia(low blood sugar levels), anemiaand hyponatremia(low sodium levels). If the onset is abrupt, collapse, shock and vomitingmay occur. ACTH deficiency is highly similar to Addison's disease, which is cortisol deficiency as the result of direct damage to the adrenal glands; the latter form, however, often leads to hyperpigmentationof the skin, which does not occur in ACTH deficiency. [cite journal |author=Arlt W, Allolio B |title=Adrenal insufficiency |journal=Lancet |volume=361 |issue=9372 |pages=1881–93 |year=2003 |month=May |pmid=12788587 |doi=10.1016/S0140-6736(03)13492-7] Thyroid-stimulating hormone(TSH) deficiency leads to hypothyroidism(lack of production of thyroxine(T4) and triiodothyronine(T3) in the thyroid). Typical symptoms are tiredness, intolerance to cold, constipation, weight gain, hair loss and slowed thinking, as well as a slowed heart rate and low blood pressure. In children, hypothyroidism leads to delayed growth and in extreme inborn forms to a syndrome called " cretinism". Prolactinplays a role in breastfeeding, and inability to breastfeed may point at abnormally low prolactin levels.
Antidiuretic hormone(ADH) deficiency leads to the syndrome of " diabetes insipidus" (unrelated to diabetes mellitus): inability to concentrate the urine, leading to polyuria(production of large amounts of clear urine) that is low in solutes, dehydrationand—in compensation—extreme thirst and constant need to drink ( polydipsia), as well as hypernatremia(high sodium levels in the blood). [cite journal |author=Maghnie M |title=Diabetes insipidus |journal=Horm. Res. |volume=59 Suppl 1 |pages=42–54 |year=2003 |pmid=12566720 |doi=10.1159/000067844] ADH deficiency may be masked if there is ACTH deficiency, with symptoms only appearing when cortisol has been replaced. Oxytocindeficiency generally causes few symptoms, as it is only required at the time of childbirthand breastfeeding.
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, and the combination of findings is still suggestive of hypopituitarism.
Levels of LH/FSH may be suppressed by a raised
prolactinlevel, and are therefore not interpretable unless prolactin is low or normal. In men, the combination of low LH and FSH in combination with a low testosteroneconfirms LH/FSH deficiency; a high testosterone would indicate a source elsewhere in the body (such as a testosterone-secreting tumor). In women, the diagnosis of LH/FSH deficiency depends on whether the woman has been through the menopause. Before the menopause, abnormal menstrual periods together with low estradioland LH/FSH levels confirm a pituitary problem; after the menopause (when LH/FSH levels are normally elevated and the ovaries produce less estradiol), inappropriately low LH/FSH alone is sufficient. Stimulation tests with GnRH are possible, but their use is not encouraged.
For TSH, basal measurements are usually sufficient, as well as measurements of
thyroxineto ensure that the pituitary is not simply suppressing TSH production in response to hyperthyroidism(an overactive thyroid gland). A stimulation test with thyrotropin-releasing hormone(TRH) is not regarded as useful. Prolactin can be measured by basal level, and is required for the interpretation of LH and FSH results in addition to the confirmation of hypopituitarism or diagnosis of a prolactin-secreting tumor.
Growth hormone deficiency is almost certain if all other pituitary tests are also abnormal, and
insulin-like growth factor 1(IGF-1) levels are decreased. If this is not the case, IGF-1 levels are poorly predictive of the presence of GH deficiency; stimulation testing with the insulin tolerance testis then required. This is performed by administering insulinto lowers the blood sugarto a level below 2.2 mmol/l. Once this occurs, growth hormone levels are measured. If they are low despite the stimulatory effect of the low blood sugars, growth hormone deficiency is confirmed. The test is not without risks, especially in those prone to seizures or are known to have heart disease, and causes the unpleasant symptoms of hypoglycemia. Alternative tests (such as the growth hormone releasing hormonestimulation test) are less useful, although a stimulation test with argininemay be used for diagnosis, especially in situations where an insulin tolerance test is thought to be too dangerous. [cite journal |author=Kaushal K, Shalet SM |title=Defining growth hormone status in adults with hypopituitarism |journal=Horm. Res. |volume=68 |issue=4 |pages=185–94 |year=2007 |pmid=17389809 |doi=10.1159/000101286] If GH deficiency is suspected, and all other pituitary hormones are normal, two different stimulation tests are needed for confirmation.
cortisollevels are over 500 nmol/l, ACTH deficiency is unlikely, whereas a level less than 100 is indicative. Levels between 100-500 require a stimulation test. This, too, is done with the insulin tolerance test. A cortisol level above 500 after achieving a low blood sugar rules out ACTH deficiency, while lower levels confirm the diagnosis. A similar stimulation test using corticotropin-releasing hormone(CRH) is not sensitive enough for the purposes of the investigation. If the insulin tolerance test yields an abnormal result, a further test measuring the response of the adrenal glands to synthetic ACTH (the ACTH stimulation test) can be performed to confirm the diagnosis.cite journal |author=Dorin RI, Qualls CR, Crapo LM |title=Diagnosis of adrenal insufficiency |journal=Ann. Intern. Med. |volume=139 |issue=3 |pages=194–204 |year=2003 |pmid=12899587 |url=http://www.annals.org/cgi/content/full/139/3/194] Stimulation testing with metyraponeis an alternative. Some suggest that an ACTH stimulation test is sufficient as first-line investigation, and that an insulin torlerance test is only needed if the ACTH test is equivocal. The insulin tolerance test is discouraged in children. None of the tests for ACTH deficiency are perfect, and further tests after a period of time may be needed if initial results are not conclusive.
Symptoms of diabetes insipidus should prompt a formal
fluid deprivation testto assess the body's response to dehydration, which normally causes concentration of the urine and increasing osmolarity of the blood. If these parameters are unchanged, desmopressin(an ADH analogue) is administered. If the urine then becomes concentrated and the blood osmolarity falls, there is a lack of ADH due to lack of pituitary function ("cranial diabetes insipidus"). In contrast, there is no change if the kidneys are unresponsive to ADH due to a different problem ("nephrogenic diabetes insipidus").
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 tomographywith radiocontrast may be used if MRI is not available. Formal visual field testing by perimetryis 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 testingmay be performed.
The pituitary gland is located at the base of the brain, and intimately connected with the
hypothalamus. It consists of two lobes: the posterior pituitary, which consists of nervous tissuebranching out of the hypothalamus, and the anterior pituitary, which consists of hormone-producing epithelium. The posterior pituitary secretes antidiuretic hormone, which regulates osmolarityof the blood, and oxytocin, which causes contractions of the uterusin childbirth and participates in breastfeeding.
The pituitary develops in the third week of
embryogenesisfrom interactions between the diencephalonpart of the brain and the nasal cavity. The brain cells secrete FGF-8, Wnt5a and BMP-4, and the nasal cavity BMP-2. Together, these cellular signals stimulate a group of cells from the nasal cavity to form Rathke's pouch, which becomes independent of the nasal cavity and develops into the anterior pituitary; this process includes the suppression of production of a protein called Sonic hedgehogby the cells of Rathke's pouch.cite journal |author=Cohen LE, Radovick S |title=Molecular basis of combined pituitary hormone deficiencies |journal=Endocr. Rev. |volume=23 |issue=4 |pages=431–42 |year=2002 |month=August |pmid=12202459 |doi=10.1210/er.2001-0030|url=http://edrv.endojournals.org/cgi/content/full/23/4/431] The cells then differentiate further into the various hormone-producing cells of the pituitary. This requires particular transcription factors that induce the expression of particular genes. Some of these transcription factors have been found to be deficient in some forms of rare combined pituitary hormone deficiencies (CPHD) in childhood. These are " HESX1", " PROP1", "POU1F1", " LHX3", " LHX4", " TBX19", " SOX2" and " SOX3". Each transcription factor acts in particular groups of cells. Therefore, various genetic mutations are associated with specific hormone deficiencies.cite journal |author=Kelberman D, Dattani MT |title=Hypothalamic and pituitary development: novel insights into the aetiology |journal=Eur. J. Endocrinol. |volume=157 Suppl 1 |issue= |pages=S3–14 |year=2007 |month=August |pmid=17785694 |doi=10.1530/EJE-07-0156 |url=http://www.eje-online.org/cgi/content/full/157/suppl_1/S3] For instance, "POU1F1" (also known as Pit-1) mutations cause specific deficiencies in growth hormone, prolactin and TSH. In addition to the pituitary, some of the transcription factors are also required for the development of other organs; some of these mutations are therefore also associated with specific birth defects.
Most of the hormones in the anterior pituitary are each part of an "axis" that is regulated by the
hypothalamus. The hypothalamus secretes a number of releasing hormones, often according to a circadian rhythm, into blood vessels that supply the anterior pituitary; most of these are stimulatory ( thyrotropin-releasing hormone, corticotropin-releasing hormone, gonadotropin-releasing hormoneand growth hormone-releasing hormone), apart from dopamine, which suppresses prolactin production. [cite journal |author=Guillemin R |title=Hypothalamic hormones a.k.a. hypothalamic releasing factors |journal=J. Endocrinol. |volume=184 |issue=1 |pages=11–28 |year=2005 |month=January |pmid=15642779 |doi=10.1677/joe.1.05883 |url=http://joe.endocrinology-journals.org/cgi/content/full/184/1/11] In response to the releasing hormone rate, the anterior pituitary produces its hormones (TSH, ACTH, LH, FSH, GH) that stimulate effector hormone glands in the body, although prolactin acts directly on the breast gland. Once the effector glands produce sufficient hormones (thyroxine, cortisol, estradiol or testosterone and IGF-1), both the hypothalamus and the pituitary cells sense their abundance and reduce their secretion of stimulating hormones. The hormones of the posterior pituitary are produced in the hypothalamus and are carried by nerve endings to the posterior lobe; their feedback system is therefore located in the hypothalamus, but damage to the nerve endings would still lead to a deficiency in hormone release.
Unless the pituitary damage is being caused by a tumor that overproduces a particular hormone, it is the lack of pituitary hormones that leads to the symptoms described above, and an excess of a particular hormone would indicate the presence of a tumor. The exception to this rule is prolactin: if a tumor compresses the
pituitary stalk, a decreased blood supply means that the lactotropecells, which produce prolactin, are not receiving dopamine and therefore produce excess prolactin. Hence, mild elevations in prolactin are attributed to stalk compression. Very high prolactin levels, though, point more strongly towards a prolactinoma(prolactin-secreting tumor).cite journal |author=Arafah BM, Nasrallah MP |title=Pituitary tumors: pathophysiology, clinical manifestations and management |journal=Endocr. Relat. Cancer |volume=8 |issue=4 |pages=287–305 |year=2001 |month=December |pmid=11733226 |doi= |url=http://erc.endocrinology-journals.org/cgi/reprint/8/4/287 | format=PDF]
Treatment of hypopituitarism is threefold: removing the underlying cause, treating the hormone deficiencies, and addressing any other repercussions that arise from the hormone deficiencies.
Pituitary tumors require treatment when they are causing specific symptoms, such as headaches, visual field defects or excessive hormone secretion.
Transsphenoidal surgery(removal of the tumor by an operation through the nose and the sphenoidal sinuses) may, apart from addressing symptoms related to the tumor, also improve pituitary function, although the gland is sometimes damaged further as a result of the surgery. When the tumor is removed by craniotomy(opening the skull), recovery is less likely–but sometimes this is the only suitable way to approach the tumor. After surgery, it make take some time for hormone levels to change significantly. Retesting the pituitary hormone levels is therefore performed 2 to 3 months later. Prolactinomas may respond to dopamine agonisttreatment–medication that mimics the action of dopamine on the lactrotrope cells, usually bromocriptineor cabergoline. This approach may improve pituitary hormone secretion in more than half the cases, and obviate the need for supplementary treatment. [cite journal |author=Schlechte JA |title=Prolactinoma |journal=N. Engl. J. Med. |volume=349 |issue=21 |pages=2035–41 |year=2003 |month=November |pmid=14627789 |doi=10.1056/NEJMcp025334]
Other specific underlying causes are treated as normally. For example, hemochromatosis is treated by venesection, the regular removal of a fixed amount of blood. Eventually, this decreases the iron levels in the body and improves the function of the organs in which iron has accumulated. [cite journal |author=Pietrangelo A |title=Hereditary hemochromatosis--a new look at an old disease |journal=N. Engl. J. Med. |volume=350 |issue=23 |pages=2383–97 |year=2004 |month=June |pmid=15175440 |doi=10.1056/NEJMra031573]
Most pituitary hormones can be replaced indirectly by administering the products of the effector glands:
hydrocortisone(cortisol) for adrenal insufficiency, levothyroxinefor hypothyroidism, testosteronefor male hypogonadism, and estradiolfor female hypogonadism (usually with a progestagento inhibit unwanted effects on the uterus). Growth hormone is available in synthetic form, but needs to be administered parenterally (by injection). Antidiuretic hormone can be replaced by desmopressin (DDAVP) tablets or nose spray. Generally, the lowest dose of the replacement medication is used to restore wellbeing and correct the deranged results, as excessive doses would cause side-effects or complications. Those requiring hydrocortisone are usually instructed to increase their dose in physically stressful events such as injury, hospitalization and dental work as these are times when the normal supplementary dose may be inadequate, putting the patient at risk of adrenal crisis.
Long-term follow up by specialists in
endocrinologyis generally needed for people with known hypopituitarism. Apart from ensuring the right treatment is being used and at the right doses, this also provides an opportunity to deal with new symptoms and to address complications of treatment.
Difficult situations arise in deficiencies of the hypothalamus-pituitary-gonadal axis in people (both men and women) who experience
infertility; infertility in hypopituitarism may be treated with subcutaneous infusions of FSH, human chorionic gonadotropin–which mimics the action of LH–and occasionally GnRH.
Several hormone deficiencies associated with hypopituitarism may lead to secondary diseases. For instance, growth hormone deficiency is associated with obesity, raised
cholesteroland the metabolic syndrome, and estradiol deficiency may lead to osteoporosis. While effective treatment of the underlying hormone deficiencies may improve these risks, it is often necessary to treat them directly.
Several studies have shown that hypopituitarism is associated with an increased risk of
cardiovascular diseaseand some also an increased risk of death of about 50% to 150% the normal population. It has been difficult to establish which hormone deficiency is responsible for this risk, as almost all patients studied had growth hormone deficiency. The studies also do not answer the question as to whether the hypopituitarism itself causes the increased mortality, or whether some of the risk is to be attributed to the treatments, some of which (such as sex hormone supplementation) have a recognized adverse effect on cardiovascular risk.
The largest study to date followed over a thousand people for eight years; it showed an 87% increased risk of death compared to the normal population. Predictors of higher risk were: female sex, absence of treatment for sex hormone deficiency, younger age at the time of diagnosis, and a diagnosis of craniopharyngioma. Apart from cardiovascular disease, this study also showed an increased risk of death from lung disease. [cite journal |author=Tomlinson JW, Holden N, Hills RK, "et al" |title=Association between premature mortality and hypopituitarism |journal=Lancet |volume=357 |issue=9254 |pages=425–31 |year=2001 |month=February |pmid=11273062|doi=10.1016/S0140-6736(00)04006-X]
Quality of lifemay be significantly reduced, even in those people on optimum medical therapy. Many report both physical and psychological problems. It is likely that the commonly used replacement therapies still do not completely mimic the natural hormone levels in the body. Health costs remain about double those of the normal population.
There is only study that has measured the
prevalence(total number of cases in a population) and incidence (annual number of new cases) of hypopituitarism. This study was conducted in Northern Spain and used hospital records in a well-defined population. The study showed that 45.5 people out of 100,000 had been diagnosed with hypopituitarism, with 4.2 new cases per year. 61% were due to tumors of the pituitary gland, 9% due to other types of lesions, and 19% due to other causes; in 11% no cause could be identified.
Recent studies have shown that people with a previous
traumatic brain injury, spontaneous subarachnoid hemorrhage(a type of stroke) or radiation therapyinvolving the head have a higher risk of hypopituitarism. [cite journal |author=Schneider HJ, Kreitschmann-Andermahr I, Ghigo E, Stalla GK, Agha A |title=Hypothalamopituitary dysfunction following traumatic brain injury and aneurysmal subarachnoid hemorrhage: a systematic review |journal=Journal of the American Medical Association |volume=298 |issue=12 |pages=1429–38 |year=2007 |month=September |pmid=17895459 |doi=10.1001/jama.298.12.1429 |url=http://jama.ama-assn.org/cgi/content/full/298/12/1429] After traumatic brain injury, as much as a quarter have persistent pituitary hormone deficiencies. [cite journal |author=Behan LA, Phillips J, Thompson CJ, Agha A |title=Neuroendocrine disorders after traumatic brain injury |journal=J. Neurol. Neurosurg. Psychiatr. |volume=79 |issue=7 |pages=753–9 |year=2008 |month=July |pmid=18559460 |doi=10.1136/jnnp.2007.132837] Many of these people may have subtle or non-specific symptoms that are not linked to pituitary problems but attributed to their previous condition. It is therefore possible that many cases of hypopituitarism remain undiagnosed, and that the annual incidence would rise to 31 per 100,000 annually if people from these risk groups were to be tested.
The pituitary was known to the ancients, such as
Galen, and various theories were proposed about its role in the body, but major clues as to the actual function of the gland were not advanced until the late 19th century, when acromegalydue to pituitary tumors was described.cite book |author=Sellwood RA, Welbourn RB, Friesen SR |title=The History of Endocrine Surgery: |publisher=Praeger Publishers |location=New York |year=1990 |pages= |isbn=0-275-92586-2] The first known report of hypopituitarism was made by the German physician and pathologist Dr Morris Simmonds. He described the condition on autopsyin a 46-year old woman who had suffered severe puerperal fevereleven years earlier, and subsequently suffered amenorrhea, weakness, signs of rapid aging and anemia. The pituitary gland was very small and there were few remnants of both the anterior and the posterior pituitary.cite journal | author=Simmonds | title=Über hypophysisschwund mit todlichem ausgang | year=1914 | journal=Dtsch Med Wschr | volume=40 | pages=322] The eponym "Simmonds' syndrome" is used infrequently for acquired hypopituitarism, especially when cachexia(general ill health and malnutrition) predominates. [WhoNamedIt|synd|2008] [DorlandsDict|nine/000956983|Simmonds disease] Most of the classic causes of hypopituitarism were described in the 20th century; the early 21st century saw the recognition of how common hypopituitarism could be in previous head injury victims.
Until the 1950s, the diagnosis of pituitary disease remained based on clinical features and visual field examination, sometimes aided by
pneumoencephalographyand X-ray tomography. Nevertheless, the field of pituitary surgery developed during this time. The major breakthrough in diagnosis came with the discovery of the radioimmunoassayby Rosalyn Yalowand Solomon Bersonin the late 1950s. [cite journal |author=Yalow RS, Berson SA |title=Immunoassay of endogenous plasma insulin in man |journal=J. Clin. Invest. |volume=39 |issue= |pages=1157–75 |year=1960 |month=July |pmid=13846364 |pmc=441860 |doi=10.1172/JCI104130] This allowed the direct measurement of the hormones of the pituitary, which as a result of their low concentrations in blood had previously been hard to measure. Stimulation tests were developed in the 1960s, and in 1973 the triple bolus testwas introduced, a test that combined stimulation testing with insulin, GnRH and TRH. [cite journal |author=Harsoulis P, Marshall JC, Kuku SF, Burke CW, London DR, Fraser TR |title=Combined test for assessment of anterior pituitary function |journal=Br Med J |volume=4 |issue=5888 |pages=326–9 |year=1973 |month=November |pmid=4202260 |pmc=1587416] Imaging of the pituitary, and therefore identification of tumors and other structural causes, improved radically with the introduction of computed tomographyin the late 1970s and magnetic resonance imaging in the 1980s.
* [http://www.pituitary.org.uk/content/view/42/ Hypopituitarism] at the Pituitary Foundation (UK)
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Look at other dictionaries:
hypopituitarism — [hī΄pō pi to͞o′i tə riz΄əm, hī΄pō pityo͞o′i tə riz΄əm] n. 1. deficient activity of the pituitary gland, esp. of its anterior lobe 2. the condition resulting from this, characterized by decreased growth in children or decreased activity of the… … English World dictionary
hypopituitarism — /huy poh pi tooh i teuh riz euhm, tyooh /, n. Pathol. 1. abnormally diminished activity of the pituitary gland, esp. of the anterior lobe. 2. the condition produced by this, characterized by obesity, retention of adolescent traits, sterility,… … Universalium
hypopituitarism — noun Etymology: International Scientific Vocabulary Date: 1909 deficient production of growth hormones by the pituitary gland • hypopituitary adjective … New Collegiate Dictionary
hypopituitarism — noun A decrease in secretion of one or more of the eight hormones normally produced by the pituitary gland … Wiktionary
hypopituitarism — A condition due to diminished activity of the anterior lobe of the hypophysis, with inadequate secretion, to varying degrees, of one or more anterior pituitary hormones. * * * hy·po·pi·tu·ita·rism .hī pō pə t(y)ü ət ə .riz əm, t(y)ü ə .triz … Medical dictionary
hypopituitarism — n. abnormally diminished activity of the pituitary gland (Medicine) … English contemporary dictionary
hypopituitarism — [ˌhʌɪpəʊpɪ tju:ɪt(ə)rɪz(ə)m] noun Medicine diminished hormone secretion by the pituitary gland, causing dwarfism and premature ageing. Derivatives hypopituitary adjective … English new terms dictionary
hypopituitarism — hy·po·pi·tu·i·ta·rism … English syllables
hypopituitarism — n. subnormal activity of the pituitary gland, causing dwarfism in childhood and a syndrome of impaired sexual function, pallor, and premature ageing in adult life (see Simmonds disease) … The new mediacal dictionary
hypopituitarism — hy•po•pi•tu•i•ta•rism [[t]ˌhaɪ poʊ pɪˈtu ɪ təˌrɪz əm, ˈtyu [/t]] n. 1) pat deficient activity of the pituitary gland, esp. of the anterior lobe 2) pat the condition produced by this, characterized by obesity, retention of adolescent traits,… … From formal English to slang