Syndrome of inappropriate antidiuretic hormone secretion

From Wikipedia, the free encyclopedia
Syndrome of inappropriate antidiuretic hormone secretion
File:Syndrome of inappropriate antidiuretic hormone.webm
Explanation of SIADH
Classification and external resources
Synonyms Schwartz-Bartter syndrome, syndrome of inappropriate antidiuresis(SIAD)
Specialty Endocrinology
ICD-10 E22.2
ICD-9-CM 253.6
DiseasesDB 12050
MedlinePlus 003702
eMedicine emerg/784 med/3541 ped/2190
MeSH D007177
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by excessive release of antidiuretic hormone from the posterior pituitary gland or another source. The increase in blood volume (hypervolemia) often results in dilutional
hyponatremia in which the plasma sodium levels are lowered and total body fluid is increased.

It was originally described in people with small-cell carcinoma of the lung, but it can be caused by a number of underlying medical conditions. The treatment may consist of fluid intake restriction, various medicines, and management of the underlying
cause. Salt administration may help prevent brain swelling by increasing attractive force to keep water in the bloodstream, preventing fluid buildup in tissue.[1] SIADH was first described in 1957.

Contents

[hide]
1 Signs and symptoms
1.1 Gastro-intestinal
1.2 Musculoskeletal
1.3 Neuro-muscular
1.4 Respiratory
1.5 Neurological
2 Causes
3 Pathophysiology
4 Diagnosis
4.1 Differential diagnosis
5 Treatment
6 History
7 References
Signs and symptoms

Gastro-intestinal

Anorexia
Nausea
Musculoskeletal

Muscle aches
Generalized muscle weakness
Neuro-muscular

Myoclonus
decreased reflexes
Ataxia
Pathological reflexes
Tremor
Asterixis
Respiratory

Cheyne-Stokes respiration
Neurological

Dysarthria
Lethargy
Confusion
Delirium
Seizures
Coma (from brain swelling)
It should be noted that prominent physical findings may be seen only in severe or rapid-onset hyponatremia.[2]

Causes

Causes of SIADH include conditions that dysregulate ADH secretion in the central nervous system, tumors that secrete ADH, drugs that either increase ADH secretion, and many others. A list of common causes is below:[3]

Central nervous system-related causes
Infections
Meningitis, Encephalitis, brain abscess, rocky mountain spotted fever, AIDS Mass / bleed
Trauma, Subarachnoid hemorrhage, subdural hematoma, cavernous sinus thrombosis hydrocephalus
Guillain-Barré syndrome
Multiple sclerosis
Cancers
Carcinomas
Lung cancers (small-cell lung cancer, mesothelioma)
gastrointestinal cancers (stomach, duodenum, pancreas)
genitourinary cancers (bladder, urethral, prostate, endometrial)
Lymphoma
Sarcomas (Ewing's sarcoma)
Pulmonary causes
Infection
Pneumonia
Lung abscess
Asthma
Cystic fibrosis
Drugs
Chlorpropamide
Ciprofloxacin[4]
Clofibrate
Moxifloxacin[4]
Phenothiazine
Ifosfamide
Cyclophosphamide
Carbamazepine
Oxcarbazepine
Valproic Acid
Selective serotonin reuptake inhibitors (SSRIs, a class of antidepressants) 3,4-Methylenedioxymethamphetamine (MDMA, commonly called Ecstasy. SIADH due to taking ecstasy was cited as a factor in the death of Leah Betts)
Oxytocin
Vincristine
Morphine
Amitriptyline
Transient causes
Endurance exercise
general anesthesia
Hereditary causes
Sarcoidosis
Pathophysiology

The normal function of ADH on the kidneys is to control the amount of water reabsorbed by kidney nephrons. ADH acts in the distal portion of the renal tubule (Distal Convoluted Tubule) as well as on the collecting duct and causes the retention of water,
but not solute. Hence, ADH activity effectively dilutes the blood (decreasing the concentrations of solutes such as sodium), causing hyponatremia; this is compounded by the fact that the body responds to water retention by decreasing aldosterone, thus
allowing even more sodium wasting. For this reason, a high urinary sodium excretion will be seen.[5]

ADH is secreted to prevent water loss in the kidneys. When water is ingested, it is taken up into the circulation and results in a dilution of the plasma. This dilution, otherwise described as a reduction in plasma osmolality, is detected by
osmoreceptors in the hypothalamus of the brain and these then switch off the release of ADH. The decreasing concentration of ADH effectively inhibits the aquaporins in the collecting ducts and distal convoluted tubules in the nephrons of the kidney.
Hence, less water is reabsorbed, thereby increasing urine output, decreasing urine osmolality, and normalizing blood osmolality.
In SIADH, the release of ADH is not inhibited by a reduction in plasma osmolality when the individual ingests water and the osmolality of the plasma drops. As the main solute of plasma is sodium, this hypoosmolar state is usually detected as a low sodium
level on laboratory testing. SIADH is therefore primarily a condition that results in the abnormal handling of water loading and not a problem with excessive solute loss. This is why it is usually treated with fluid restriction. Diuretics (furosemide
specifically) may also be given to decrease reabsorption of water, but care must be taken not to correct water imbalances too rapidly.[4]

This causes dilutional hyponatremia and all the consequences associated with that condition: headache, nausea, vomiting, and confusion may ensue. Severe hyponatremia may cause convulsions or coma.[4]

The abnormalities underlying type D syndrome of inappropriate antidiuretic hormone hypersecretion concern individuals where vasopressin release and response are normal but where abnormal renal expression and translocation of aquaporin 2, or both are
found.[6] It has been suggested that this is due to abnormalities in the secretion of secretin in the brain and that "Secretin as a neurosecretory hormone from the posterior pituitary, therefore, could be the long-sought vasopressin independent mechanism
to solve the riddle that has puzzled clinicians and physiologists for decades."[6]

In general, increased ADH causes water retention without interstitial fluid volume expansion and without edema or hypertension. The water retention causes hyponatremia, which is a key feature in SIADH. This is purely a problem of water metabolism with no
abnormalities in total body sodium metabolism.[7] Hyponatremia and inappropriately concentrated urine (UOsm >100 mOsm/L)[8] are seen, as well as no signs of edema or hypovolemia. When hyponatremia is severe (sodium <120 mOsm), or acute in onset, symptoms
of cerebral edema become prominent (irritability, confusion, seizures, and coma).

Diagnosis

Laboratory findings in diagnosis of SIADH include:

Euvolemic hyponatremia <134 mEq/L, and POsm <275 mOsm/kg OR ( POsm - Serum [Urea]mmol/l < 280 mOsm/kg )
Urine osmolality >100mOsm/kg of water during hypotonicity[4]
Urine sodium concentration >40 mEq/L with normal dietary salt intake
Other findings:

Clinical euvolemia without edema or ascites
Low blood urea nitrogen (BUN)
Normal serum creatinine[9]
Low uric acid
Normal Acid-Base, K+ balance
Normal Adrenal, Thyroid function
Differential diagnosis

Antidiuretic hormone (ADH) is released from the posterior pituitary for a number of physiologic reasons. The majority of patients with hyponatremia, other than those with excessive water intake (polydipsia) or renal salt wasting will have elevated ADH as
the cause of their hyponatremia. However, not every patient with hyponatremia and elevated ADH has SIADH. One approach to a patient with hyponatremia is to divide ADH release into appropriate (not SIADH) or inappropriate (SIADH).[10]

Appropriate ADH release can be a result of hypovolemia, a so-called osmotic trigger of ADH release. This may be true hypovolemia, as a result of dehydration with fluid losses replaced by free water (seen sometimes in Marathon runners[11] as well as in
acutely ill patients). It can also be perceived hypovolemia, as in the conditions of congestive heart failure (CHF) and cirrhosis in which the kidneys perceive a lack of intravascular volume. The hyponatremia caused by appropriate ADH release (from the
kidneys' perspective) in both CHF and cirrhosis have been shown to be an independent poor prognostic indicator of mortality.[12][13]

Appropriate ADH release can also be a result of non-osmotic triggers. Symptoms such as nausea/vomiting and pain are significant causes of ADH release.[14] The combination of osmotic and non-osmotic triggers of ADH release can adequately explain the
hyponatremia in the majority of patients who are hospitalized with acute illness and are found to have mild to moderate hyponatremia. SIADH is less common than appropriate release of ADH. While it should be considered in a differential, other causes
should be considered as well.
Cerebral salt wasting syndrome (CSWS) also presents with hyponatremia, there are signs of dehydration for which reason the management is diametrically opposed to SIADH.[15] Importantly CSWS can be associated with subarachnoid hemorrhage (SAH) which may
require fluid supplementation rather than restriction to prevent brain damage.[16]

Most cases of hyponatremia in children are caused by appropriate secretion of antidiuretic hormone rather than SIADH or another cause.[17]

Treatment

Management of SIADH includes:

Treating underlying causes when possible.
Long-term fluid restriction of 1,200-1,800 mL/day[18] will increase serum sodium through decreasing total body water.
For very symptomatic patients (severe confusion, convulsions, or coma) hypertonic saline (3%) 1-2 ml/kg IV in 3-4 h should be given.
Drugs
Demeclocycline can be used in chronic situations when fluid restrictions are difficult to maintain; demeclocycline is the most potent inhibitor of Vasopressin (ADH/AVP) action. However, demeclocycline has a 2-3 day delay in onset with extensive side
effect profile, including skin photosensitivity, and nephrotoxicity.[19]
Urea: oral daily ingestion has shown favorable long-term results with protective effects in myelinosis and brain damage.[19] Limitations noted to be undesirable taste and is contraindicated in patients with cirrhosis to avoid initiation or potentiation
of hepatic encephalopathy.
Conivaptan - an antagonist of both V1A and V2 vasopressin receptors. Its indications are "treatment of euvolemic hyponatremia (e.g. the syndrome of inappropriate secretion of antidiuretic hormone, or in the setting of hypothyroidism, adrenal
insufficiency, pulmonary disorders, etc.) in hospitalized patients."[20] Conivaptan, however, is only available as a parenteral preparation.[19]
Tolvaptan - an antagonist of the V2 vasopressin receptor. A randomized controlled trial showed tolvaptan is able to raise serum sodium in patients with euvolemic or hypervolemic hyponatremia in 2 different tests. Combined analysis of the 2 trials showed
an improvement in hyponatremia in both the short term (primary sodium change in average AUC: 3.62+/- 2.68 and 4.35 +/-2.87) and long term with long term maintenance (primary sodium change in average AUC: 6.22 +/- 4.22 and 6.20 +/- 4.92), at 4 days and 30
days, respectively. Tolvaptan's side effect profile is minimal. Discontinuation of the Tolvaptan showed return of hyponatremia to control values at their respective time frames.[21]
No head-to-head study is currently available to quantify and compare the relative efficacies of V2 vasopressin receptor antagonists with demeclocycline or other treatment options.
Care must be taken when correcting hyponatremia. A rapid rise in the sodium level may cause central pontine myelinolysis.[22] Avoid correction by more than 12 mEq/L/day. Initial treatment with hypertonic saline may abruptly lead to a rapid dilute
diuresis and fall in ADH. Rapid diuresis may lead to over-rapid rise in serum sodium, and should be managed with extreme care.
History

The condition was first described by researchers from Boston, Massachusetts and Bethesda, Maryland (including Dr Frederic Bartter) in two patients with lung cancer.[23] Criteria were developed by Schwartz and Bartter in 1967[24] and have remained
essentially unchanged since then.[25] The condition is occasionally referred to by the names of the authors of the first report - Schwartz-Bartter syndrome.[26]

References

Ramming, Scott; Shackford, Steven R.; Zhuang, Jing; Schmoker, Joseph D. (1994). "The relationship of fluid balance and sodium administration to cerebral edema formation and intracranial pressure in a porcine model of brain injury". The Journal of Trauma
37 (5): 705-13. doi:10.1097/00005373-199411000-00003. PMID 7966466.
Syndrome of Inappropriate Antidiuretic Hormone Secretion at eMedicine
Ellison, David H.; Berl, Tomas (2007). "The Syndrome of Inappropriate Antidiuresis". New England Journal of Medicine 356 (20): 2064-72. doi:10.1056/NEJMcp066837. PMID 17507705.
Babar, S. M. (2013). "SIADH Associated With Ciprofloxacin". Annals of Pharmacotherapy 47 (10): 1359-63. doi:10.1177/1060028013502457. PMID 24259701.
Le, Tao, Vikas Bhushan, Matthew Sochat, Max Petersen, Goran Micevic, and Kimberly Kallianos. "Endocrine." First Aid for the USMLE Step 1 2014: A Student-to-Student Guide. Pg 326. Print.
Chu, J. Y. S.; Lee, L. T. O.; Lai, C. H.; Vaudry, H.; Chan, Y. S.; Yung, W. H.; Chow, B. K. C. (2009). "Secretin as a neurohypophysial factor regulating body water homeostasis". Proceedings of the National Academy of Sciences 106 (37): 15961-6. Bibcode:
2009PNAS..10615961C. doi:10.1073/pnas.0903695106. JSTOR 40484830. PMC 2747226. PMID 19805236.
Onitilo, A. A.; Kio, E.; Doi, S. A. R. (2007). "Tumor-Related Hyponatremia". Clinical Medicine & Research 5 (4): 228-37. doi:10.3121/cmr.2007.762. PMC 2275758. PMID 18086907.
Adrogué, Horacio J.; Madias, Nicolaos E. (2000). "Hyponatremia". New England Journal of Medicine 342 (21): 1581-9. doi:10.1056/NEJM200005253422107. PMID 10824078.
Modric, Jan. "SIADH". eHealthStar.com. Retrieved 21 October 2015.
Ishikawa, San-e; Saito, Takako; Fukagawa, Akinori; Higashiyama, Minori; Nakamura, Tomoatsu; Kusaka, Ikuyo; Nagasaka, Shoichiro; Honda, Kazufumi; Saito, Toshikazu (2001). "Close Association of Urinary Excretion of Aquaporin-2 with Appropriate and
Inappropriate Arginine Vasopressin-Dependent Antidiuresis in Hyponatremia in Elderly Subjects". The Journal of Clinical Endocrinology & Metabolism 86 (4): 1665-71. doi:10.1210/jcem.86.4.7426. PMID 11297601.
Almond, Christopher S.D.; Shin, Andrew Y.; Fortescue, Elizabeth B.; Mannix, Rebekah C.; Wypij, David; Binstadt, Bryce A.; Duncan, Christine N.; Olson, David P.; Salerno, Ann E.; Newburger, Jane W.; Greenes, David S. (2005). "Hyponatremia among Runners in
the Boston Marathon". New England Journal of Medicine 352 (15): 1550-6. doi:10.1056/NEJMoa043901. PMID 15829535.
Baldasseroni, Samuele; Urso, Renato; Orso, Francesco; Bianchini, Bianca P.; Carbonieri, Emanuele; Cirò, Antonio; Gonzini, Lucio; Leonardi, Giuseppe; Marchionni, Niccolò; Maggioni, Aldo P. (2011). "Relation between serum sodium levels and prognosis in
outpatients with chronic heart failure". Journal of Cardiovascular Medicine 12 (10): 723-31. doi:10.2459/JCM.0b013e32834ae87e. PMID 21873881.
Kim, W. Ray; Biggins, Scott W.; Kremers, Walter K.; Wiesner, Russell H.; Kamath, Patrick S.; Benson, Joanne T.; Edwards, Erick; Therneau, Terry M. (2008). "Hyponatremia and Mortality among Patients on the Liver-Transplant Waiting List". New England
Journal of Medicine 359 (10): 1018-26. doi:10.1056/NEJMoa0801209. PMC 4374557. PMID 18768945.
Fisher, RD; Rentschler, RE; Nelson, JC; Godfrey, TE; Wilbur, DW (1982). "Elevation of plasma antidiuretic hormones (ADH) associated with chemotherapy-induced emesis in man". Cancer Treatment Reports 66 (1): 25-9. PMID 7053263.
Petzold A (2015). "Disorders of plasma sodium". N Engl J Med 372 (13): 1267. doi:10.1056/nejmc1501342. PMID 25806925.
Sen J, Belli A, Albon H; et al. (2003). "Triple-H therapy in the management of aneurysmal subarachnoid haemorrhage". The Lancet Neurology 2 (10): 614-621. doi:10.1016/s1474-4422(03)00531-3. PMID 14505583.
Rivkees, Scott A (2008). "Differentiating appropriate antidiuretic hormone secretion, inappropriate antidiuretic hormone secretion and cerebral salt wasting: the common, uncommon, and misnamed". Current Opinion in Pediatrics 20 (4): 448-52. doi:10.1097/
MOP.0b013e328305e403. PMID 18622203.
Schürer, Ludwig; Wolf, Stefan; Lumenta, Christianto B. (2010). "Water and Electrolyte Regulation". In Lumenta, Christianto B.; Di Rocco, Concezio; Haase, Jens; et al. Neurosurgery. European Manual of Medicine. pp. 611-5. doi:10.1007/978-3-540-79565-0_40.
ISBN 978-3-540-79565-0.
Zietse, R.; van der Lubbe, N.; Hoorn, E. J. (2009). "Current and future treatment options in SIADH". Clinical Kidney Journal 2 (Suppl_3): iii12-iii19. doi:10.1093/ndtplus/sfp154. PMC 2762827. PMID 19881932.
"Vaprisol (conivaptan hydrochloride) Liquid [Astellas Pharma US, Inc.]". Retrieved 2007-06-08.
Schrier, Robert W.; Gross, Peter; Gheorghiade, Mihai; Berl, Tomas; Verbalis, Joseph G.; Czerwiec, Frank S.; Orlandi, Cesare (2006). "Tolvaptan, a Selective Oral Vasopressin V2-Receptor Antagonist, for Hyponatremia". New England Journal of Medicine 355 (
20): 2099-112. doi:10.1056/NEJMoa065181. PMID 17105757.
Ashrafian, H.; Davey, P. (2001). "A review of the causes of central pontine myelinosis: yet another apoptotic illness?". European Journal of Neurology 8 (2): 103-9. doi:10.1046/j.1468-1331.2001.00176.x. PMID 11430268.
Schwartz, William B.; Bennett, Warren; Curelop, Sidney; Bartter, Frederic C. (1957). "A syndrome of renal sodium loss and hyponatremia probably resulting from inappropriate secretion of antidiuretic hormone". The American Journal of Medicine 23 (4): 529-
42. doi:10.1016/0002-9343(57)90224-3. PMID 13469824. reproduced in Schwartz, William B.; Bennett, Warren; Curelop, Sidney; Bartter, Frederic C. (2001). "A syndrome of renal sodium loss and hyponatremia probably resulting from inappropriate secretion of
antidiuretic hormone. 1957". Journal of the American Society of Nephrology 12 (12): 2860-70. PMID 11729259.
Bartter, Frederic C.; Schwartz, William B. (1967). "The syndrome of inappropriate secretion of antidiuretic hormone". The American Journal of Medicine 42 (5): 790-806. doi:10.1016/0002-9343(67)90096-4. PMID 5337379.
Verbalis, Joseph G.; Goldsmith, Stephen R.; Greenberg, Arthur; Schrier, Robert W.; Sterns, Richard H. (2007). "Hyponatremia Treatment Guidelines 2007: Expert Panel Recommendations". The American Journal of Medicine 120 (11 Suppl 1): S1-21. doi:10.1016/j.
amjmed.2007.09.001. PMID 17981159.
Schwartz-Bartter syndrome at Who Named It?
Retrieved from "https://en.wikipedia.org/w/index.php?title=Syndrome_of_inappropriate_antidiuretic_hormone_secretion&oldid=701866512"
Categories: Pituitary disordersSyndromesOncological Emergencies
This page was last modified on 27 January 2016, at 01:35.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia(R) is a registered trademark of the Wikimedia Foundation, Inc., a non-
profit organization.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)