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==Causes==
==Causes==
'''Hyponatremia results from:'''
* '''Decreased renal excretion of water''' is the most cases of hyponatremia, secondary to persistent action of ADH.
* '''Blood sampling''' from a vein that is being infused with hypotonic medications.
* '''Older techniques''' (e.g., flame photometry) for sodium measurement, high levels of protein or triglyceride can cause false hyponatremia (Pseudohyponatremia).
* '''Hyperglycemia''' can also cause hyponatremia, osmotic water movement from cells into the blood, resulting in a relative decrease in serum sodium concentration in the absence of hypo-osmolality.
(for each 100-mg/dL increase in glucose concentration above 100 mg/dL The sodium concentration should be increased by approximately 1.6 to 2 mmol/L)
* '''Excess water intake''' is a rare cause of hyponatremia.In psychogenic polydipsia, ingesting large volumes (>15-20 L/day) of water results in hyponatremia, in spite of preserved renal function and diluting ability.
* '''Medications''' which interfere with urinary dilution (thiazide diuretics and nonsteroidal anti-inflammatory drugs [NSAIDs]).
* '''Clinical disorders''' ( congestive heart failure, nephrotic syndrome, cirrhosis) with the reduction in effective arterial blood volume, resulting in persistent ADH activity despite hypo-osmolar plasma.
* '''Acute or chronic renal failure''' results in reduced functional nephron mass, decreased glomerular filtration rate, and therefore decreased capacity for water excretion.
===Common Causes===
===Common Causes===
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Saeedeh Kowsarnia M.D. [2]
Overview
Disease name] may be caused by [cause1], [cause2], or [cause3].
OR
Common causes of [disease] incl ude [cause1], [cause2], and [cause3].
OR
The most common cause of [disease name] is [cause 1]. Less common causes of [disease name] include [cause 2], [cause 3], and [cause 4].
OR
The cause of [disease name] has not been identified. To review risk factors for the development of [disease name], click here .
Causes
Common Causes
Diagnostic criteria of SIADH/SIAD
serum sodium <135 mEq/L
Plasma osmolality <275 mOsm/kg , ( NL=275–295 mOsm/kg)
urine concentration UOsm >100mOsm/kg H2O, (NL=500-800 mOsm/kg H2O)
Urine sodium >30 (20-40) mmol/L, with normal salt and water intake, (NL=20 mEq/L)†
Exclusion of glucocorticoid deficiency or hypothyroidism
† Mmol and Meq are the same for univalent ions like sodium
Causes of Hyponatremia based upon Serum Osmolality:
Classification
Serum Osmolality
Etiology
Hypertonic Hyponatremia
> 295 mOsm/kg
Isotonic Hyponatremia
280 – 295 mOsm/kg
Lab/blood draw error, Hyper paraproteinemia (monoclonal gammopathy of undetermined significance (MGUS),
Multiple Myeloma), Hyperlipidemia, Post TURP (bladder irrigation with osmotic solutions)
Hypotonic Hyponatremia
< 280 mOsm/kg
Hyperglycemia, Mannitol, Glycerol, Sorbitol Etiology depends upon volume status (Hypervolemic/ Euvolemic/ Hypovolemic)
Causes of Hyponatremia based on volume status [1] :
Volume status
Sodium status
Causes
Hypovolemic
Hyponatremia[2]
total body water ↓
total body sodium ↓↓
GI loss: Vomiting, diarrhea, tube drainage
Insensible loss: Sweating, burns
Renal loss: Salt-wasting nephropathy (Inappropriate loss of Na+-Cl– in the urine),
Bicarbonaturia ( Renal tubular acidosis, Metabolic alkalosis), Osmotic diuresis
Third spacing of fluids : Pancreatitis, hypoalbuminemia
Cerebral salt-wasting syndrome : Stroke ,SAH (urinary salt wasting, brain natriuretic peptide ↑)
Mineralocorticoid deficiency: Addison disease
Excessive diuretic administration
Hypervolemic
Hyponatremia
total body water ↑↑
total body sodium ↑
Renal disease: Acute or chronic kidney disease or injury
(due to relatively higher water versus salt intake and poor excretion),Nephrotic syndrome
Congestive heart failure
Cirrhosis
Iatrogenic
Euvolemic
Hyponatremia
total body water ↑
total body sodium ↔
Drugs: Vasopressin, diuretics, antidepressants, opioids
SIADH: Malignancy, central nervous system (CNS) disorders, pulmonary disease, or drugs,
postoperative nausea, pain,stress,Neoplasia (common),trauma,pregnancy
High fluid intake: Physical activity, surgery, primary polydipsia, potomania
(caused by a low intake of solutes with relatively high fluid intake)
Medical testing (excess fluid intake) : Colonoscopy or cardiac catheterization
Hypothyroidism
Glucocorticoid deficiency
Reset osmostat †
Iatrogenic
† Altered sensitivity to serum osmolality by the hypothalamic osmoreceptors
Drug Mechanisms
Drug Classification
Increase ADH secretion
Antidepressants: Tricyclic antidepressants ( Amitryptiline,
Protriptyline, Desipramine),Selective serotonin reuptake inhibitors,
Monoamine oxidase inhibitors
Antipsychotic drugs: Phenothiazines (Thioridazine, Trifluoperazine),
Butyrophenones (Haloperidol)
Antiepileptic drugs: Carbamazepine, Oxcarbazepine, Sodium valproate
Anticancer agents: Vinca alkaloids (Vincristine, Vinblastine),
Platinum compounds (Cisplatin, Carboplatin)
Alkylating agents: Intravenous, Cyclophosphamide, Melphalan, Ifosfamide
Miscellaneous: Methotrexate, Interferon, Levamisole, Pentostatin, Monoclonal antibodies, MDMA, Nicotine
Opiates
Increase ADH effect
Antiepileptic drugs: Carbamazepine, Lamotrigine
Antidiabetic drugs: Chlorpropamide, Tolbutamide
Anticancer agents: Alkylating agents (Intravenous cyclophosphamide)
NSAIDS
Drugs affecting water and sodium homeostasis
Diuretics: Thiazides, Indapamide, Amiloride, Loop diuretics
Reset omostat ‡
Antidepressants: Venlafaxine
Antiepileptic drugs: Carbamazepine
‡ Altered sensitivity to serum osmolality by the hypothalamic osmoreceptors
Causes by Organ System
Cardiovascular
Congestive heart failure
Chemical / poisoning
No underlying causes
Dermatologic
Burns
Drug Side Effect
ACE inhibitors , Ajuga nipponensis makino , Asenapine maleate , Cefpodoxime , Chlorpropamide , Cyclophosphamide , Desmopressin , Diuretics , Duloxetine , Eslicarbazepine acetate , Ethacrynic Acid , Felbamate , Fluvoxamine , Interferon gamma , Ixabepilone , Losartan and Hydrochlorothiazide , Nilotinib , Nivolumab , Nonsteriodal anti-inflammatory drugs , Oxcarbazepine , Pramipexole , Rifaximin , Tiagabine , Tolazamide , Zonisamide , Tolbutamide , Vortioxetine
Ear Nose Throat
No underlying causes
Endocrine
Addison's disease , Corticosterone methyloxidase type I deficiency , Diabetes mellitus , Diabetic coma , Glucocorticoid deficiency , Familial hyperreninemic hypoaldosteronism type 2 , Hypothyroidism , Mineralocorticoid deficiency , Myxedema coma , Syndrome of inappropriate antidiuretic hormone , Thyrotropin deficiency , 18-Hydroxylase deficiency , Familial hypoaldosteronism
Environmental
No underlying causes
Gastroenterologic
Acute liver failure , Cirrhosis , Congenital chloride diarrhea , Diarrhea , Gastrointestinal fistula , Ileus , Necrotizing enterocolitis , Pancreatitis , Peritonitis , Vomiting , Cystic fibrosis
Genetic
18-Hydroxylase deficiency , Bartter Syndrome type 4 , Cystic fibrosis , Familial hypoaldosteronism , Corticosterone methyloxidase type I deficiency , Familial hyperreninemic hypoaldosteronism type 2 , Congenital chloride diarrhea
Hematologic
No underlying causes
Iatrogenic
After pituitary surgery , After surgery , Ascitic tap , Gastric drainage , Hypotonic infusions , Pleuracentesis
Infectious Disease
Malignant boutonneuse fever , Neonatal bacterial meningitis , Peritonitis
Musculoskeletal / Ortho
No underlying causes
Neurologic
Intracranial hemorrhage , Subarachnoid hemorrhage , Pituitary cancer
Nutritional / Metabolic
Hyperlipidemia , Hyperproteinemia , Hypoalbuminemia , Low sodium diet , Metabolic acidosis , Diabetic coma
Obstetric/Gynecologic
Pregnancy
Oncologic
Pituitary cancer
Opthalmologic
No underlying causes
Overdose / Toxicity
Water intoxication
Psychiatric
Psychogenic polydipsia , Psychosis , Self-induced water intoxication and schizophrenic disorders syndrome
Pulmonary
Cystic fibrosis
Renal / Electrolyte
Acute kidney disease , Chronic kidney disease , Diuresis , Glucosuria , Ketonuria , Nephrotic syndrome , Renal Tubular Acidosis , Tubulointerstitial kidney disease , Bartter Syndrome type 4 , Corticosterone methyloxidase type I deficiency , Renal failure
Rheum / Immune / Allergy
Addison's disease , Nephrotic syndrome
Sexual
Cystic fibrosis
Trauma
Burns
Urologic
No underlying causes
Dental
No underlying causes
Miscellaneous
Beer potomania , Ecstasy abuse , Factitious hyponatremia , Hydration , Massive edema , Pseudohyponatremia , Water Intoxication , Hyperlipidemia , Hyperproteinemia , Hypoalbuminemia , Exercise associated hyponatremia
Causes in Alphabetical Order
References
↑ Guillaumin, Julien; DiBartola, Stephen P. (2017). "A Quick Reference on Hyponatremia". Veterinary Clinics of North America: Small Animal Practice . 47 (2): 213–217. doi :10.1016/j.cvsm.2016.10.003 . ISSN 0195-5616 .
↑ Rondon-Berrios, Helbert; Agaba, Emmanuel I.; Tzamaloukas, Antonios H. (2014). "Hyponatremia: pathophysiology, classification, manifestations and management". International Urology and Nephrology . 46 (11): 2153–2165. doi :10.1007/s11255-014-0839-2 . ISSN 0301-1623 .
↑ Liamis, George; Milionis, Haralampos; Elisaf, Moses (2008). "A Review of Drug-Induced Hyponatremia". American Journal of Kidney Diseases . 52 (1): 144–153. doi :10.1053/j.ajkd.2008.03.004 . ISSN 0272-6386 .