Hypopituitarism
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2008-07-16T22:28:17Z
Jfdwolff
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/* Pathophysiology */ starting sourced content
{{Infobox_Disease
| Name = {{PAGENAME}}
| Image =
| Caption =
| DiseasesDB = 6522
| ICD10 = {{ICD10|E|23|0|e|20}}, {{ICD10|E|89|3|e|70}}
| ICD9 = {{ICD9|253.7}}
| ICDO =
| OMIM =
| MedlinePlus =
| eMedicineSubj = emerg
| eMedicineTopic = 277
| eMedicine_mult = {{eMedicine2|med|1137}} {{eMedicine2|ped|1130}} |
| MeshID = D007018
}}
'''Hypopituitarism''' is the decreased secretion (''hypo'') of one or more [[hormone]]s from the [[pituitary gland]] at the base of the [[brain]].<ref name=Schneider>{{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}}</ref> If there is impaired production of multiple hormones, the term '''panhypopituitarism''' (''pan'' meaning "all") is used.<ref name=Schneider/> The pituitary gland consists of two parts. The [[anterior pituitary]] produces [[thyroid-stimulating hormone]] (TSH), [[gonadotropins]] (LH and FSH), [[prolactin]], [[adrenocorticotropic hormone]] (ACTH) and [[growth hormone]]. The [[posterior pituitary]] secretes [[antidiuretic hormone]] (ADH) and [[oxytocin]]. These hormones act by stimulating hormone production in other glands elsewhere in the body, and some (ADH, oxytocin and prolactin) directly influence the function of organs.<ref name=Schneider/>
The symptoms of hypopituitarism depend on the hormones that are underproduced, such as weight gain and tiredness due to [[growth hormone deficiency]] and excessive urine production due to a lack of [[antidiuretic hormone]] (a state known as [[diabetes insipidus]]). The diagnosis of hypopituitarism is made by [[blood test]]s, but often [[medical imaging|specific scans]] and other investigations are needed to find the underlying cause and ideal treatment. Most hormones of the pituitary can be replaced by tablets or injections.<ref name=Schneider/> Hypopituitarism is a [[rare disease]], but may be significantly underdiagnosed in people with previous [[traumatic brain injury]].<ref name=Schneider/>
==Signs and symptoms==
{{expand | date=July 2008}}
==Diagnosis==
Hypopituitarism may come to medical attention by symptoms or features of pituitary hormone deficiency (e.g., poor [[growth]], [[hypoglycemia]], [[micropenis]], [[delayed puberty]], [[polyuria]], [[impaired libido]], [[Fatigue (physical)|fatigue]], and many others), or because the physician has diagnosed one of the many disorders and conditions associated with hypopituitarism listed above and tests for it. A provocative test ([[triple bolus test]]) measures the secretory response of the pituitary to a stimulus (other hormones, drugs, exercise, etc.) by measuring serum levels of the hormone involved.
==Causes==
{| class="prettytable" style = "width:75%; font-size:90%; margin-left:15px; text-align:center"
!width="20%"| Type
! Causes
|-
! Tumors
| align="left" |Most cases of hypopituitarism are due to [[pituitary adenoma]]s, and rarely other tumors compressing the normal tissue in the gland. Compression may also arise from benign [[brain tumor]]s outside the gland—[[craniopharyngioma]], [[meningioma]], [[chordoma]], [[ependymoma]], [[glioma]] or [[metastasis]] from [[cancer]] elsewhere in the body.<ref name=Schneider/>
|-
!Infection, inflammation and infiltration
| align="left"| The pituitary may also be affected by [[infection]]s of the brain ([[cerebral abscess]], [[meningitis]], [[encephalitis]]) or of the gland itself (usually viral hypophysitis), or it may be infiltrated by abnormal cells ([[neurosarcoidosis]], [[histiocytosis]]) or excessive iron {[[hemochromatosis]]). [[Empty sella syndrome]] is unexplained disappearance of pituitary tissue, probably due to outside pressure. [[Autoimmune hypophysitis]] occurs when the immune system directly attacks the pituitary.<ref name=Schneider/>
|-
!Vascular
|align="left"| In the time around [[childbirth]], the pituitary gland is vulnerable to [[low blood pressure]], such as may result form [[hemorrhage]]; pituitary damage due to [[postpartum hemorrhage|bleeding after childbirth]] is called [[Sheehan's syndrome]]. [[Pituitary apoplexy]] is hemorrhage or [[infarction]] (loss of blood supply) of the pituitary. [[Stroke]] is increasingly recognized as a cause for hypopituitarism.<ref name=Schneider/>
|-
!Physical
| align="left"| External physical causes for hypopituitarism include [[traumatic brain injury]], [[subarachnoid hemorrhage]], [[neurosurgery]] and [[ionizing radiation]] (e.g. [[radiation therapy]] for a previous brain tumor).<ref name=Schneider/>
|-
!Congenital
| align="left"| [[Congenital]] hypopituitarism (present at birth) may be the result of complications around delivery, or may be the result of insufficient development (hypoplasia) of the gland, sometimes in the context of specific genetic abnormalities.<ref name=Schneider/>
|}
==Pathophysiology==
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 tissue]] branching out of the hypothalamus, and the anterior pituitary, which consists of hormone-producing [[epithelium]]. The posterior pituitary secretes [[antidiuretic hormone]], which regulates [[osmolarity]] of the blood, and [[oxytocin]], which causes [[Contraction (childbirth)|contractions]] of the [[uterus]] in childbirth and participates in [[lactation|breastfeeding]].<ref name=Schneider/>
The anterior pituitary produces six hormones: [[prolactin]] (PRL) - stimulates [[milk]] production in the [[breast]]
#[[growth hormone]] (GH) - growth and [[glucose]] homeostasis
#[[luteinizing hormone]] (LH) - [[menstrual cycle]] and reproduction
#[[follicle stimulating hormone]] (FSH) - same
#[[thyroid stimulating hormone]] (TSH) - stimulates [[thyroxine]] production in the [[thyroid]]
#[[adrenocorticotropic hormone]] (ACTH) - stimulates [[glucocorticoid]] production in the [[adrenal gland]]
These hormones are secreted in individually characteristic pulsatile patterns, often with distinct [[circadian rhythm]], rather than at steady rates throughout 24 hours.
Deficiency of a single pituitary hormone occurs less commonly than deficiency of more than one hormone. Sometimes referred to as progressive pituitary hormone deficiency or partial hypopituitarism, there is usually a predictable order of hormone loss.
Generally, growth hormone is lost first, then luteinizing hormone deficiency follows. The loss of follicle-stimulating hormone, thyroid stimulating hormone, adrenocorticotopic hormones and prolactin typically follow much later. The progressive loss of pituitary hormone secretion is usually a slow process, which can occur over a period of months or years. Hypopituitarism does occasionally start suddenly with rapid onset of symptoms
As for the posterior pituitary, antidiuretic hormone deficiency is the main problem, while oxytocin deficiency rarely causes clinically significant problems.
==Treatment==
{{Expand | date=July 2008}}
Hypopituitarism and panhypopituitarism are treated by replacement of appropriate hormones. Since most of the anterior pituitary hormones are [[protein]]s or [[glycoprotein]]s released in pulsatile patterns, whose functions are to induce secretion of smaller molecule hormones ([[thyroid]] hormones and [[steroid]]s), it is simpler and less expensive for most purposes to simply replace the target gland hormones. There are a few exceptions, such as fertility induction.
*[[growth hormone|GH]] is replaced with [[growth hormone treatment|growth hormone]].
*TSH is replaced with [[thyroxine]].
*ACTH is usually replaced with [[hydrocortisone]] but any [[glucocorticoid]] may be used.
*LH and FSH are most often replaced by supplying the appropriate [[sex steroid]]s (e.g., [[testosterone]] or [[estrogen]] and [[progestin]]). Virtually all people who need T or E2 replacement for hypopituitarism rarely have spontaneous, effective [[spermatogenesis]] or [[ovarian follicle|follicular]] maturation. Both [[GnRH]] by subcutaneous pump and [[gonadotropin]]s (Pergonal) by daily subcutaneous injections have been used effectively to induce [[infertility|fertility]].
*Prolactin is not usually replaced, as [[infant formula]] is readily available, simpler, and much cheaper.
*ADH is replaced most commonly with oral, nasal, and sometimes intravenous or subcutaneous [[desmopressin]].
*[[Oxytocin]] is most important during labor and delivery at the end of pregnancy, and can be replaced in that circumstance by synthetic [[oxytocin]].
*It has recently been shown that there is a decreased risk of nonfatal stroke in both genders and of nonfatal cardiac events in GHD men due to the larger prescription of cardioprotective drugs and to 6 years of GH-replacement. The increased prevalence of T2DM in GHD women can be partly attributed to a higher body mass and to decreased physical activity.
==Epidemiology==
There is only study that has measured the [[prevalence]] (total number of cases in a population) and [[incidence (epidemiology)|incidence]] (annual number of new cases) of hypopituitarism.<ref name=Schneider/> 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.<ref name=Regal>{{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}}</ref> 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.<ref name=Schneider/><ref name=Regal/> The most common problem was LH/FSH insufficiency; growth hormone deficiency was more common in people with a tumor than those with other causes.<ref name=Regal/>
Recent studies have shown that people with a previous [[traumatic brain injury]], spontaneous [[subarachnoid hemorrhage]] (a type of stroke) or [[radiation therapy]] involving the head have a higher risk of hypopituitarism. Many of these people may have subtle on 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.<ref name=Schneider/>
==History==
The first known report of hypopituitarism was made by the [[Germany|German]] physician and pathologist Dr [[Morris Simmonds]]. He described the condition on [[autopsy]] in a 46-year old woman who had suffered severe [[puerperal fever]] eleven 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 adeno- and neurohypophysis.<ref name=Schneider/><ref name=Simmonds1914>{{cite journal | author=Simmonds | title=Uber hypophysisschwund mit todlichem ausgang | year=1914 | journal=Dtsch Med Wschr | volume=40 | pages=322}}</ref> The eponym ''Simmonds' syndrome'' is used infrequently for acquired hypopituitarism.<ref>{{WhoNamedIt|synd|2008}}</ref>
==See also==
* [[growth hormone deficiency]]
* [[pituitary gland]]
* [[Kallmann syndrome]]
* [[Empty sella syndrome]]
* [[Insulin tolerance test]]
* [[ACTH stimulation test]]
== References ==
{{reflist}}
==External links==
* [http://www.pituitary.org.uk/content/view/42/ Hypopituitarism] at the Pituitary Foundation (UK)
{{Endocrine pathology}}
[[Category:Neuroendocrinology]]
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