Ver el código de «Syndrome of inappropriate antidiuretic hormone secretion»

==Background==
*Abbreviation: SIADH
*Inappropriate or continued action of ADH despite normal/increased plasma volume→ impaired water excretion→ hyponatremia and hypo-osmolality

==Clinical Features==
*See [[hyponatremia]]
*Symptoms of neoplasm, particularly lung neoplasm

==Differential Diagnosis (Causes)==
*Inappropriate or hypersecretion from hypothalamus
**Infectious
***[[Brain abscess]]
***[[Encephalitis]], [[meningitis]]
***[[Rocky mountain spotted fever]]
***[[Herpes Zoster]]
**Vascular/hemorrhagic
***[[Stroke]], hypoxic ischemic encephalopathy, perinatal hypoxia
***[[Cavernous sinus thrombosis]]
***[[Subarachnoid hemorrhage]]
***[[Subdural hematoma]]
**Other
***[[Acute intermittent porphyria]]
***Cerebellar and cerebral atrophy
***CNS [[lupus]]
***[[Epilepsy]], [[Delirium tremens]]
***[[Multiple sclerosis]], [[Guillain-Barré Syndrome]]
***[[Hydrocephalus]], ventriculoatrial shunt obstruction
***[[Wernicke encephalopathy]]
***[[Head trauma]]
*Ectopic ADH secretion due to neoplastic source
**Lung carcinoma, mesothelioma
**Duodenal, pancreatic, and [[colon cancer|colonic carcinomas]]
**Adrenocortical, bladder/urothelial, ovarian, prostate, and cervical cancers
**[[Brain tumor]], [[leukemia]]/[[lymphoma]], carcinoid, neuroblastoma, thymoma, Ewing's sarcoma
*Pulmonary disorders
*Drugs
**ADH-stimulating
***Acetylcholine, histamine
***Antineoplastic agents - Adenine arabinoside, [[cyclophosphamide]], ifosfamide, vincristine, vinblastine
***[[Barbiturates]], [[thiopental]], [[Mono amine oxidase inhibitor toxicity|MAOIs]], [[tricyclic antidepressants]]
***[[Opioids]]
***[[Haloperidol]], [[phenothiazines]]
***[[Carbamazepine]], [[oxcarbazepine]]
***Halothane, [[nitrous oxide]]
***[[Bromocriptine]]
***Carbachol
**Chlorpropamide
***[[Isoproterenol]]
***[[nicotine toxicity|Nicotine]]
**ADH-potentiating
***[[Griseofulvin]]
***Hypoglycemic agents – [[Metformin]], phenformin, tolbutamide
***[[Oxytocin]] (large doses)
***[[Indomethacin]], [[aspirin]], [[NSAIDs]]
***[[Theophylline]]
***Vasopressin analogs (eg, AVP, [[DDAVP]])

==Evaluation==
===Essential Criteria<ref>Schwartz WB, Bennett W, Curelop S, Bartter FC. A syndrome of renal sodium loss and hyponatremia probably resulting from inappropriate secretion of antidiuretic hormone. American Journal of Medicine 1957 23 529–542</ref>===
*Effective serum osmolality <275 mOsm/kg
*Urine specific gravity > 1.015
*Urine osmolality >100 mOsm/kg at some level of decreased effective osmolality
*Clinical euvolemia
*Urine [[hyponatremia|sodium concentration]] >30 mmol/l with normal dietary salt and water intake
*Absence of adrenal, thyroid, pituitary or renal insufficiency
*No recent use of [[diuretic]] agents

===Supplemental criteria===
*Serum uric acid <0.24 mmol/l (<4mg/dl)
*Serum urea <3.6 mmol/l (<21.6mg/dl)
*Failure to correct [[hyponatremia]] after 0.9% saline infusion
*Fractional sodium excretion >0.5%
*Fractional urea excretion >55%
*Fractional uric acid excretion >12%
*Correction of [[hyponatremia]] through fluid restriction

==Management<ref>Verbalis JG et al. Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. Am J Med. 2013 Oct;126(10 Suppl 1):S1-42.</ref>==
*See [[hyponatremia]]
*Fluid restriction
*Oral salt tablets (NaCl) for mild-moderate hyponatremia
*100 cc bolus of 3% NaCl for severe symptoms, repeat if neurologic symptoms persist or worsen
**Ideally given through central line
*DO NOT give normal saline 0.9%
**In SIADH, sodium handling is intact and renal system will excrete Na
**Water handling out of balance from excessive ADH
**All sodium will be excreted, urine osmolality will remain high
**Half of the bolus of normal saline will be retained, worsening hyponatremia
*See [[osmotic demyelination syndrome]] for excessively rapid overcorrection

==Disposition==
*See [[hyponatremia]]

==References==
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[[Category:FEN]]