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| {{CMG}} | | {{CMG}} |
| | ==[[Diabetes insipidus overview|Overview]]== |
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| ==Overview== | | ==[[Diabetes insipidus historical perspective|Historical Perspective]]== |
| '''Diabetes insipidus''' ('''DI''') is a [[disease]] characterized by excretion of large amounts of severely diluted [[urine]], which cannot be reduced when fluid intake is reduced. It denotes inability of the kidney to concentrate urine. DI is caused by a deficiency of [[antidiuretic hormone]] (ADH), also known as vasopressin, or by an insensitivity of the [[kidney]]s to that hormone. It can also be induced [[iatrogenic]]ally by the diuretic [[conivaptan]].
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| ==Pathophysiology== | | ==[[Diabetes insipidus classification|Classification]]== |
| * [[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)
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| * DI is characterized by chronic excretion of very large amounts of urine
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| * DI is coupled with [[Ddx:Dehydration|dehydration]] and excessive thirst
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| 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.
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| 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]].
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| 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.
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| There are several forms of DI:
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| * ''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.
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| * ''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.
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| * ''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.
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| * ''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.
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| ==Signs and Symptoms== | | ==[[Diabetes insipidus pathophysiology|Pathophysiology]]== |
| Excessive urination and extreme thirst (especially for cold water) are typical for DI. Symptoms of diabetes insipidus are quite similar to those of untreated [[diabetes mellitus]], with the distinction that the urine is not sweet as it does not contain glucose and there is no [[hyperglycemia]] (elevated [[blood glucose]]). Blurred vision is a rarity. The extreme urination continues throughout the day and the night. In children, DI can interfere with appetite, eating, weight gain, and [[human development (biology)|growth]] as well. They may present with [[fever]], [[vomiting]], or [[diarrhea]]. Adults with untreated DI may remain healthy for decades as long as enough water is drunk to offset the urinary losses. However, there is a continuous risk of [[dehydration]].
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| ==Diagnosis== | | ==[[Diabetes insipidus causes|Causes]]== |
| In order to distinguish DI from other causes of excess urination, [[blood glucose]], [[bicarbonate]] and [[calcium]] need to be tested. Measurement of blood [[electrolyte]]s can reveal a high [[sodium]] level ([[hypernatremia]] as [[dehydration]] develops). [[Urinalysis]] demonstrates a dilute urine with a low [[specific gravity]]. Urine [[osmolality]] and electrolyte levels are typically low.
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| A ''fluid deprivation test'' helps determine whether DI is caused by:
| | ==[[Diabetes insipidus differential diagnosis|Differentiating Diabetes insipidus from other Diseases]]== |
| # excessive intake of fluid
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| # a defect in [[antidiuretic hormone|ADH]] production
| | ==[[Diabetes insipidus epidemiology and demographics|Epidemiology and Demographics]]== |
| # a defect in the kidneys' response to [[antidiuretic hormone|ADH]]
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| This test measures changes in body weight, urine output, and urine composition when fluids are withheld. Sometimes measuring blood levels of ADH during this test is also necessary.
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| To distinguish between the main forms, [[desmopressin]] stimulation is also used; desmopressin can be taken by injection, a nasal spray, or a tablet. While taking desmopressin, a patient should drink fluids or water only when thirsty and not at other times, as this can lead to sudden fluid accumulation in central nervous system. If desmopressin reduces urine output and increases osmolarity, the pituitary production of ADH is deficient, and the kidney responds normally. If the DI is due to renal pathology, desmopressin does not change either urine output or osmolarity.
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| If central DI is suspected, testing of other hormones of the [[pituitary]], as well as [[magnetic resonance imaging]] (MRI), is necessary to discover if a disease process (such as a [[prolactinoma]], or [[histiocytosis]], [[syphilis]], [[tuberculosis]] or other [[tumor]] or [[granuloma]]) is affecting pituitary function.
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| Habit drinking (in its severest form termed [[psychogenic polydipsia]]) is the most common imitator of diabetes insipidus at all ages. While many adult cases in the medical literature are associated with mental disorders, most patients with habit polydipsia have no other detectable disease. The distinction is made during the water deprivation test, as some degree of urinary concentration above isosmolar is usually obtained before the patient becomes dehydrated.
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| == Differential Diagnosis == | | ==[[Diabetes insipidus risk factors|Risk Factors]]== |
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| ==== [[Nephrogenic Diabetes Insipidus]] ====
| | ==[[Diabetes insipidus screening|Screening]]== |
| * Acute tubular necrosis
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| * [[Amyloidosis]]
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| * Drugs
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| * Genetic
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| * Granuloma
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| * [[Ddx:Hypercalcemia|Hypercalcemia]]
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| * [[Ddx:Hyperkalemia|Hyperkalemia]]
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| * Polycystic kidneys
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| * Pregnancy
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| * Sarcoma
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| * [[Sickle Cell Disease]]
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| * Urinary tract obstruction
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| ==== [[Pituitary Diabetes Insipidus]] ====
| | ==[[Diabetes insipidus natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
| * [[Adenoma]]s
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| * [[Aneurysm]]
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| * [[Aortocoronary bypass]]
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| * Chemical toxins
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| * Congenital pituitary malformations
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| * Craniopharyngeoma
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| * [[Encephalitis]]
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| * Genetic
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| * [[Granuloma]]s
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| * Head trauma
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| * [[Hypoxic encephalopathy]]
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| * [[Leukemia]]
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| * [[Lymphoma]]
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| * Lymphocytic neurohypophysitis
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| * [[Meningitis]]
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| * [[Metastase]]s
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| * Posthypophysectomy
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| * [[Sarcoidosis]]
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| * [[Scleroderma]]
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| * [[Sheehan's Syndrome]]
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| * [[Stroke]]
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| * [[Systemic Lupus Erythematosus]]
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| * [[Toxoplasmosis]]
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| * [[Tuberculosis]]
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| * [[Wegener's Granulomatosis]]
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| ==== Primary Polydipsia ==== | | ==Diagnosis== |
| * Drugs
| | [[Diabetes insipidus history and symptoms|History and Symptoms]] | [[Diabetes insipidus physical examination|Physical Examination]] | [[Diabetes insipidus laboratory findings|Laboratory Findings]] | [[Diabetes insipidus electrocardiogram|Electrocardiogram]] | [[Diabetes insipidus head x ray|Head X Ray]] | [[Diabetes insipidus CT|CT]] | [[Diabetes insipidus MRI|MRI]] | [[Diabetes insipidus vision_test|Vision Test]] | [[Diabetes insipidus other imaging findings|Other Imaging Findings]] | [[Diabetes insipidus other diagnostic studies|Other Diagnostic Studies]] |
| * Granulomas
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| * Head trauma
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| * Iatrogenic
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| * [[Multiple Sclerosis]]
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| * [[Obsessive-Compulsive Disorder]]
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| * [[Schizophrenia]]
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| * [[Tuberculosis]]
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| ==Treatment== | | ==Treatment== |
| Central DI and gestational DI respond to [[desmopressin]]. In dipsogenic DI, [[desmopressin]] is not usually an option. [[Desmopressin]] will be ineffective in nephrogenic DI. Instead, the [[diuretic]] [[hydrochlorothiazide]] (HCT or HCTZ) or [[indomethacin]] can improve NDI; HCT is sometimes combined with [[amiloride]] to prevent [[hypokalemia]]. Again, adequate hydration is important for patients with DI, as they may become dehydrated easily.
| | [[Diabetes insipidus medical therapy|Medical Therapy]] | [[Diabetes insipidus primary prevention|Primary Prevention]] | [[Diabetes insipidus secondary prevention|Secondary Prevention]] | [[Diabetes insipidus cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Diabetes insipidus future or investigational therapies|Future or Investigational Therapies]] |
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| ==Sources== | | ==Case Studies== |
| * ''The [[public domain]] document "Diabetes Insipidus", [[NIH]] Publication No. 01-4620, December 2000.''
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| ==External links==
| | [[Diabetes insipidus case study one|Case #1]] |
| [http://diabetesinsipidus.org/ The Diabetes Insipidus Foundation, Inc] | |
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