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{{Diabetes insipidus}}
{{Diabetes insipidus}}
{{CMG}}
{{CMG}}; {{AE}} {{DAMI}}
==Overview==
==Overview==
The [[posterior pituitary]] consists of the [[Paraventricular nucleus of hypothalamus|paraventricular]] and [[Supraoptic nucleus|supraoptic nuclei]], which synthesize [[oxytocin]] and [[arginine vasopressin|arginine vasopressin,]] respectively. In cases of [[Central diabetes insipidus|central DI]], there is an absence of [[vasopressin]], which is responsive to the exogenous administration of [[desmopressin]]. On the contrary, in cases of [[Nephrogenic diabetes insipidus|nephrogenic DI]], [[solute]] excretion and all filtration functions of the [[kidney]] are normal, but [[urine]] is [[hypotonic]] and there is a characteristic resistance to the [[antidiuretic]] effects of both [[endogenous]] and [[exogenous]] administration of [[vasopressin]]. More than 55 different [[genetic mutations]] resulting in a defective [[prohormone]] and a deficiency of [[ADH]] have been identified in familial [[Central diabetes insipidus|central diabetes]]. Many conditions have been associated with the development of [[diabetes insipidus]] such as [[Wolfram syndrome]] (also known as DIDMOAD), [[Langerhans cell histiocytosis]] (LCH), [[Sickle-cell disease|sickle cell disease]], [[amyloidosis]], and several others.
==Pathogenesis==
==Pathogenesis==
===Central Diabetes Insipidus===
The [[posterior pituitary]] consists of the [[Paraventricular nucleus|paraventricular]] and [[Supraoptic nucleus|supraoptic]] nuclei that synthesize [[oxytocin]] and [[arginine vasopressin]], respectively. The [[axons]] of these [[hormones]] project to the [[neurohypophysis]], where the [[hormones]] are secreted into the [[blood stream|bloodstream]] to allow for maximum anti-diuresis over the course of 5–10 days. The maintenance of water balance in healthy humans is achieved principally by three interrelated determinants:
*[[Thirst]]
*[[ADH|AVP]]
*[[Kidney]] function
[[ADH]] acts on the [[kidney]], where it increases [[urine osmolality]]. It binds to the [[V2 receptor|V2 receptors]] in the [[basolateral membrane]] of the [[Collecting duct system|renal collecting tube]] and activates the [[Adenyl cyclases|Gs-adenyl cyclase]] system, increasing intracellular levels of [[Cyclic adenosine monophosphate|cyclic 3′,5′-adenosine monophosphate]] ([[Cyclic adenosine monophosphate|cAMP]]) and thus activating [[protein kinase A]], which in turn phosphorylates preformed [[Aquaporin 2|AQP2 water channels]] localized in intracellular [[vesicles]].<ref name="pmid16209125">{{cite journal| author=Agre P| title=Nobel Lecture. Aquaporin water channels. | journal=Biosci Rep | year= 2004 | volume= 24 | issue= 3 | pages= 127-63 | pmid=16209125 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16209125  }} </ref>
===Nephrogenic Diabetes Insipidus===
In cases of [[Nephrogenic diabetes insipidus|nephrogenic DI]], [[solute]] [[excretion]] and all [[filtration]] functions of the [[kidney]] are normal, but [[urine]] is [[hypotonic]] and there is a characteristic resistance to the [[antidiuretic]] effects of [[endogenous]] [[vasopressin]]. Abnormalities in the [[medullary]] [[osmotic]] [[gradient]], directed by [[antidiuretic  hormone]] ([[ADH]]) or [[arginine vasopressin]] ([[AVP]]) and inhibition of the action of [[ADH]] on the [[renal tubules]], are both thought to be mechanisms by which [[Nephrogenic diabetes insipidus|nephrogenic DI]] develops. The lack of response to [[ADH]] is due to the inhibition of  [[adenylate cyclase]] and the resultant decreased formation of [[Cyclic adenosine monophosphate|cAMP]]. [[cAMP]] serves as a second messenger to [[Protein kinase A|protein kinase A]] and facilitates the fusion of [[aquaporin]] storage vesicles to the [[luminal]] cell wall, which in turn allows the [[Collecting duct system|collecting ducts]] to become [[permeable]] and reabsorb water.
===Psychogenic Diabetes Insipidus===
This [[Disorder (medicine)|disorder]] is also known as [[Factitious disorder|factitious]] diabetes insipidus, a condition whereby, due to some [[psychological]] [[Disorder (medicine)|disorder]], a patient drinks an excessive amount of water, thereby decreasing the [[plasma osmolarity]] and suppressing the release of [[ADH]]. This leads to [[polyuria]]. The presence of a psychoneurotic disorder, the absence of a preference for iced fluids, and prompt [[Antidiuretic effect|antidiuresis]] in response to the administration of [[Hypertonic|hypertonic saline,]] [[nicotine]], or water deprivation will usually establish the [[diagnosis]].
===Gestational Diabetes Insipidus===
This disorder is classically identified during [[pregnancy]] in a woman of childbearing age. Gestational diabetes insipidus (DI) is a very rare [[complication]] of pregnancy. Undiagnosed and untreated cases may lead to serious complications in both the mother and the fetus. Gestational DI results when an [[enzyme]] made by the [[placenta]] destroys [[ADH]] in the mother. The [[placenta]] is the system of [[blood vessels]] and other tissues that develops with the [[fetus]]. The [[placenta]] allows for the exchange of [[nutrients]] and waste products between mother and [[fetus]]. Most cases of gestational DI can be treated with [[desmopressin]]. In rare cases, however, an abnormality in the thirst mechanism causes gestational DI, and [[desmopressin]] should not be used.<ref name="pmid26707038">{{cite journal| author=Ejmocka-Ambroziak A, Grzechocińska B, Jastrzebska H, Kochman M, Cyganek A, Wielgoś M et al.| title=Gestational diabetes insipidus. Case Report. | journal=Neuro Endocrinol Lett | year= 2015 | volume= 36 | issue= 5 | pages= 410-3 | pmid=26707038 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26707038  }} </ref>


==Genetics==
==Genetics==
More than 55 different [[genetic mutations]] resulting in a defective [[prohormone]] and a deficiency of [[AVP]] have been implicated in the development of familial [[Central diabetes insipidus|central diabetes]].<ref name="ChristensenRittig2006">{{cite journal|last1=Christensen|first1=Jane H.|last2=Rittig|first2=Søren|title=Familial Neurohypophyseal Diabetes Insipidus—An Update|journal=Seminars in Nephrology|volume=26|issue=3|year=2006|pages=209–223|issn=02709295|doi=10.1016/j.semnephrol.2006.03.003}}</ref> The majority of relevant [[genetic mutations]] have an [[autosomal dominant]] form of inheritance.<ref name="GhirardelloGarrè2007">{{cite journal|last1=Ghirardello|first1=S.|last2=Garrè|first2=M.-L.|last3=Rossi|first3=A.|last4=Maghnie|first4=M.|title=The Diagnosis of Children with Central Diabetes Insipidus|journal=Journal of Pediatric Endocrinology and Metabolism|volume=20|issue=3|year=2007|issn=2191-0251|doi=10.1515/JPEM.2007.20.3.359}}</ref>


==Associated Conditions==
==Associated Conditions==
Conditions associated with DI include:
*[[Langerhans cell histiocytosis]] (LCH)
*[[Wolfram syndrome]], also known as DIDMOAD ([[diabetes insipidus]], [[Diabetes mellitus|diabetes mellitus,]] [[Optic atrophy|optic atrophy,]] and [[deafness]])
*[[Sickle-cell disease|Sickle cell disease]]
*[[Amyloidosis]]
*[[Obstructive uropathy]]
*[[Electrolyte disturbance|Electrolyte disturbances]] (e.g., [[hypokalemia]] and [[hypercalcemia]]) 
*[[Pregnancy]]
*Conditions induced by a drug (e.g., [[lithium]], [[demeclocycline]], [[amphotericin B]], and [[vincristine]])
**[[Lithium]] is the most  common cause of drug-induced [[Nephrogenic diabetes insipidus|nephrogenic DI]]


==Gross Pathology==
==Gross Pathology==
There are no gross pathology findings associated with diabetes insipidus.


==Microscopic Pathology==
==Microscopic Pathology==
* [[Diabetes Insipidus|Diabetes insipidus]] (DI) is an endocrine disorder involving deficient production or lack of effective action of pituitary antidiuretic hormone (ADH, AVP, arginine vaopressin)
There are no microscopic findings associated with diabetes insipidus.
* DI is characterized by chronic excretion of very large amounts of urine
 
* DI is coupled with [[Ddx:Dehydration|dehydration]] and excessive thirst
Electrolyte and volume [[homeostasis]] is a complex mechanism that balances the body's requirements for [[blood pressure]] and the main electrolytes [[sodium]] and [[potassium]]. In general, electrolyte regulation precedes volume regulation. When the volume is severely depleted, however, the body will retain water at the expense of deranging electrolyte levels.
The regulation of urine production occurs in the [[hypothalamus]], which produces [[antidiuretic hormone]] (ADH or vasopressin) in the [[Supraoptic nucleus|supraoptic]] and [[Paraventricular nucleus|paraventricular]] nuclei.  After synthesis, the hormone is transported in neurosecretory granules down the axon of the hypothalamic neuron to the posterior lobe of the [[pituitary gland]] where it is stored for later release. In addition, the hypothalamus regulates the sensation of thirst in the [[ventromedial nucleus]] by sensing increases in serum osmolarity and relaying this information to the [[Cerebral cortex|cortex]].
The main effector organ for [[body water|fluid]] homeostasis is the [[kidney]]. ADH acts by increasing water permeability in the [[collecting ducts]], specifically it acts on proteins called [[aquaporin]]s which open to allow water into the collecting duct cells. This increase in permeability allows for reabsorption of water into the bloodstream, thus concentrating the urine.
There are several forms of DI:
* ''Central'' diabetes insipidus is due to damage to the hypothalamus or pituitary due to a [[tumor]], [[cerebrovascular accident|stroke]], [[neurosurgery]] or some rather rare causes (which include [[hemochromatosis]], [[sarcoidosis]], [[histiocytosis]], diseases that can form masses in the vicinity like a [[tuberculoma]] or [[syphilis]] and some [[genetic disorder]]s). If the hypothalamus is damaged, the feeling of thirst may be completely absent.
* ''Nephrogenic'' diabetes insipidus is due to the inability of the kidney to respond normally to ADH. There are hereditary causes (90% are due to mutations of the ADH V2 receptor, and 10% mutations of the [[aquaporin#AQP2|aquaporin 2]] water channel), but these are rare (incidence is around 4 per million live births). Most are male, because V2 receptor mutations are x-linked recessive defects. More common are acquired forms of NDI, which occur as a side-effect to some [[medication]]s (such as [[lithium citrate]] and [[amphotericin B]]), as well as in [[polycystic kidney disease]] (PKD) and [[sickle-cell disease]], and electrolyte disturbances such as hypokalaemia and hypercalcaemia. In some cases, no cause is found.
* ''Dipsogenic'' DI is due to a defect or damage to the thirst mechanism, which is located in the hypothalamus. This defect results in an abnormal increase in thirst and fluid intake that suppresses ADH secretion and increases urine output. Desmopressin is ineffective, and can lead to fluid overload as the thirst remains.
* ''Gestational'' DI only occurs during [[pregnancy]]. While all pregnant women produce ''vasopressinase'' in the [[placenta]], which breaks down ADH, this can assume extreme forms in GDI. Most cases of gestational DI can be treated with desmopressin. In rare cases, however, an abnormality in the thirst mechanism causes gestational DI, and [[desmopressin]] should not be used.
==References==
==References==
{{reflist|2}}
{{reflist|2}}
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[[Category:Endocrinology]]
[[Category:Endocrinology]]
[[Category:Nephrology]]
[[Category:Nephrology]]
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Latest revision as of 19:49, 26 October 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Omodamola Aje B.Sc, M.D. [2]

Overview

The posterior pituitary consists of the paraventricular and supraoptic nuclei, which synthesize oxytocin and arginine vasopressin, respectively. In cases of central DI, there is an absence of vasopressin, which is responsive to the exogenous administration of desmopressin. On the contrary, in cases of nephrogenic DI, solute excretion and all filtration functions of the kidney are normal, but urine is hypotonic and there is a characteristic resistance to the antidiuretic effects of both endogenous and exogenous administration of vasopressin. More than 55 different genetic mutations resulting in a defective prohormone and a deficiency of ADH have been identified in familial central diabetes. Many conditions have been associated with the development of diabetes insipidus such as Wolfram syndrome (also known as DIDMOAD), Langerhans cell histiocytosis (LCH), sickle cell disease, amyloidosis, and several others.

Pathogenesis

Central Diabetes Insipidus

The posterior pituitary consists of the paraventricular and supraoptic nuclei that synthesize oxytocin and arginine vasopressin, respectively. The axons of these hormones project to the neurohypophysis, where the hormones are secreted into the bloodstream to allow for maximum anti-diuresis over the course of 5–10 days. The maintenance of water balance in healthy humans is achieved principally by three interrelated determinants:

ADH acts on the kidney, where it increases urine osmolality. It binds to the V2 receptors in the basolateral membrane of the renal collecting tube and activates the Gs-adenyl cyclase system, increasing intracellular levels of cyclic 3′,5′-adenosine monophosphate (cAMP) and thus activating protein kinase A, which in turn phosphorylates preformed AQP2 water channels localized in intracellular vesicles.[1]

Nephrogenic Diabetes Insipidus

In cases of nephrogenic DI, solute excretion and all filtration functions of the kidney are normal, but urine is hypotonic and there is a characteristic resistance to the antidiuretic effects of endogenous vasopressin. Abnormalities in the medullary osmotic gradient, directed by antidiuretic hormone (ADH) or arginine vasopressin (AVP) and inhibition of the action of ADH on the renal tubules, are both thought to be mechanisms by which nephrogenic DI develops. The lack of response to ADH is due to the inhibition of adenylate cyclase and the resultant decreased formation of cAMP. cAMP serves as a second messenger to protein kinase A and facilitates the fusion of aquaporin storage vesicles to the luminal cell wall, which in turn allows the collecting ducts to become permeable and reabsorb water.

Psychogenic Diabetes Insipidus

This disorder is also known as factitious diabetes insipidus, a condition whereby, due to some psychological disorder, a patient drinks an excessive amount of water, thereby decreasing the plasma osmolarity and suppressing the release of ADH. This leads to polyuria. The presence of a psychoneurotic disorder, the absence of a preference for iced fluids, and prompt antidiuresis in response to the administration of hypertonic saline, nicotine, or water deprivation will usually establish the diagnosis.

Gestational Diabetes Insipidus

This disorder is classically identified during pregnancy in a woman of childbearing age. Gestational diabetes insipidus (DI) is a very rare complication of pregnancy. Undiagnosed and untreated cases may lead to serious complications in both the mother and the fetus. Gestational DI results when an enzyme made by the placenta destroys ADH in the mother. The placenta is the system of blood vessels and other tissues that develops with the fetus. The placenta allows for the exchange of nutrients and waste products between mother and fetus. Most cases of gestational DI can be treated with desmopressin. In rare cases, however, an abnormality in the thirst mechanism causes gestational DI, and desmopressin should not be used.[2]

Genetics

More than 55 different genetic mutations resulting in a defective prohormone and a deficiency of AVP have been implicated in the development of familial central diabetes.[3] The majority of relevant genetic mutations have an autosomal dominant form of inheritance.[4]

Associated Conditions

Conditions associated with DI include:

Gross Pathology

There are no gross pathology findings associated with diabetes insipidus.

Microscopic Pathology

There are no microscopic findings associated with diabetes insipidus.

References

  1. Agre P (2004). "Nobel Lecture. Aquaporin water channels". Biosci Rep. 24 (3): 127–63. PMID 16209125.
  2. Ejmocka-Ambroziak A, Grzechocińska B, Jastrzebska H, Kochman M, Cyganek A, Wielgoś M; et al. (2015). "Gestational diabetes insipidus. Case Report". Neuro Endocrinol Lett. 36 (5): 410–3. PMID 26707038.
  3. Christensen, Jane H.; Rittig, Søren (2006). "Familial Neurohypophyseal Diabetes Insipidus—An Update". Seminars in Nephrology. 26 (3): 209–223. doi:10.1016/j.semnephrol.2006.03.003. ISSN 0270-9295.
  4. Ghirardello, S.; Garrè, M.-L.; Rossi, A.; Maghnie, M. (2007). "The Diagnosis of Children with Central Diabetes Insipidus". Journal of Pediatric Endocrinology and Metabolism. 20 (3). doi:10.1515/JPEM.2007.20.3.359. ISSN 2191-0251.

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