Hyponatremia resident survival guide: Difference between revisions
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==Causes== | ==Causes== | ||
Hyponatremia causes can be classified into 3 types based on calculating serum osmolality, which is calculated as follows: | Hyponatremia causes can be classified into 3 types based on calculating serum osmolality, which is calculated as follows:<br> | ||
Sosm(mmol/kg) = (2 x serum Na<sup>+</sup> conc.) + (serum glucose conc./18) + (blood urea nitrogen/2.8) | Sosm(mmol/kg) = (2 x serum Na<sup>+</sup> conc.) + (serum glucose conc./18) + (blood urea nitrogen/2.8) | ||
Where Ssom is Serum osmolality. | Where Ssom is Serum osmolality. | ||
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<ref name="Pham-2006">{{Cite journal | last1 = Pham | first1 = PC. | last2 = Pham | first2 = PM. | last3 = Pham | first3 = PT. | title = Vasopressin excess and hyponatremia. | journal = Am J Kidney Dis | volume = 47 | issue = 5 | pages = 727-37 | month = May | year = 2006 | doi = 10.1053/j.ajkd.2006.01.020 | PMID = 16632011 }}</ref> | <ref name="Pham-2006">{{Cite journal | last1 = Pham | first1 = PC. | last2 = Pham | first2 = PM. | last3 = Pham | first3 = PT. | title = Vasopressin excess and hyponatremia. | journal = Am J Kidney Dis | volume = 47 | issue = 5 | pages = 727-37 | month = May | year = 2006 | doi = 10.1053/j.ajkd.2006.01.020 | PMID = 16632011 }}</ref> | ||
:* Arterial blood volume depletion | :* Arterial blood volume depletion | ||
:: | ::# True blood volume depletion (Diarrhea, vomiting, bleeding, use of diuretics) | ||
:: | ::# Thiazide diuretic induced<ref name="Leung-2011">{{Cite journal | last1 = Leung | first1 = AA. | last2 = Wright | first2 = A. | last3 = Pazo | first3 = V. | last4 = Karson | first4 = A. | last5 = Bates | first5 = DW. | title = Risk of thiazide-induced hyponatremia in patients with hypertension. | journal = Am J Med | volume = 124 | issue = 11 | pages = 1064-72 | month = Nov | year = 2011 | doi = 10.1016/j.amjmed.2011.06.031 | PMID = 22017784 }}</ref> | ||
::# Heart failure<ref name="Oren-2005">{{Cite journal | last1 = Oren | first1 = RM. | title = Hyponatremia in congestive heart failure. | journal = Am J Cardiol | volume = 95 | issue = 9A | pages = 2B-7B | month = May | year = 2005 | doi = 10.1016/j.amjcard.2005.03.002 | PMID = 15847851 }}</ref> | |||
:: | |||
:* Syndrome of inappropriate antidiuretic hormone secretion(SIADH) | :* Syndrome of inappropriate antidiuretic hormone secretion(SIADH) | ||
Revision as of 17:49, 28 January 2014
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.D. [2]
Definition
Hyponatremia is defined as a serum sodium concentration < 135 meq/L.
Causes
Hyponatremia causes can be classified into 3 types based on calculating serum osmolality, which is calculated as follows:
Sosm(mmol/kg) = (2 x serum Na+ conc.) + (serum glucose conc./18) + (blood urea nitrogen/2.8)
Where Ssom is Serum osmolality.
♦ Hyponatremia with low serum osmolality[1] [2] [3]
- Arterial blood volume depletion
- Syndrome of inappropriate antidiuretic hormone secretion(SIADH)
♦ Hyponatremia with high or normal serum osmolality
- Marked hyperglycemia
- Pseudohyponatremia
- Noncoductive irrigation solutions
Life Threatening Causes
Conditions that may cause death or permanent disability within the next 24 hours
Common Causes
Management
| Serum sodium < 135 mEq/L | |||||||||||||||||||||||||||||||||||||||||||||
| Plasma osmolality | |||||||||||||||||||||||||||||||||||||||||||||
| Hypotonic < 280 | Isotonic/Hypertonic (Pseudohyponatremia) > 280 | ||||||||||||||||||||||||||||||||||||||||||||
| Assess volume status | Increase in osmotically active compounds; glucose, protein, lipid, mannitol, sorbitol | ||||||||||||||||||||||||||||||||||||||||||||
| Hypovolemia | Hypervolemia | Euvolemia | Treat etiology | ||||||||||||||||||||||||||||||||||||||||||
| Spot urine Na < 10, BUN/Creatinine > 20:1, Urine osmolality > 450 | Same as hypovolemia, Spot urine Na < 10, BUN/Creatinine > 20:1, Urine osmolality > 450 | Spot urine Na > 20, BUN/Creatinine < 20:1, Urine osmolality > 300 | |||||||||||||||||||||||||||||||||||||||||||
| GI, renal losses, dehydration, diuretics, adrenal insufficiency, cerebral salt wasting syndrome | heart failure cirrhosis renal failure | Urine osmolality > 300 | Urine osmolality 50-100 | ||||||||||||||||||||||||||||||||||||||||||
| (a) Normal saline; (b) If neurological sign/symptoms 3% hypertonic saline, and furosemide | Fluid restriction, Diuretics, Treat etiology | SIADH, Hypothyroidism | Compulsive water drinking | ||||||||||||||||||||||||||||||||||||||||||
| (a) Fluid restriction (b) Demeclocycline (if fluid restriction fails) (c) Vaptans; Conivaptan, Tolvaptan for resistant cases | Treat etiology | ||||||||||||||||||||||||||||||||||||||||||||
Do's
1) Cerebral salt wasting syndrome causes hypo-osmolar hyponatremia with lab parameters similar to that seen in SIADH. It is associated with conditions like hypovolemia, hypotension, neurosurgical procedure, and subarachnoid hemorrhage (within previous 10 days). It is treated as hypoosmolar hyponatremia.
2) While deciding the rate of normal saline for hypovolemia hyponatremia, consideration of the following factors are helpful: patient's BMI (faster rates for higher BMI), cardiac (slower rate for low ejection fraction) and renal function (slower rates for low GFRs).
3) Common causes of SIADH are, small cell lung cancer, intracranial pathology, increased intrathoracic pathology, medications (thiazides, SSRI, tricyclic antidepressant, narcotics, phenothiazine, carbamazepine)
4) Vaptans such as conivaptan (intravenous), and tolvaptans (oral preparations) can be used for resistant euvolemic, and hypervolemic hyponatremia. These are very expensive and should be initiated in hospital.
Don'ts
1) Serum sodium shouldn't be corrected faster than 0.5 meq/h, as faster correction increases the risk for central pontine myelinolysis.
References
- ↑ Anderson, RJ.; Chung, HM.; Kluge, R.; Schrier, RW. (1985). "Hyponatremia: a prospective analysis of its epidemiology and the pathogenetic role of vasopressin". Ann Intern Med. 102 (2): 164–8. PMID 3966753. Unknown parameter
|month=ignored (help) - ↑ Chung, HM.; Kluge, R.; Schrier, RW.; Anderson, RJ. (1987). "Clinical assessment of extracellular fluid volume in hyponatremia". Am J Med. 83 (5): 905–8. PMID 3674097. Unknown parameter
|month=ignored (help) - ↑ Pham, PC.; Pham, PM.; Pham, PT. (2006). "Vasopressin excess and hyponatremia". Am J Kidney Dis. 47 (5): 727–37. doi:10.1053/j.ajkd.2006.01.020. PMID 16632011. Unknown parameter
|month=ignored (help) - ↑ Leung, AA.; Wright, A.; Pazo, V.; Karson, A.; Bates, DW. (2011). "Risk of thiazide-induced hyponatremia in patients with hypertension". Am J Med. 124 (11): 1064–72. doi:10.1016/j.amjmed.2011.06.031. PMID 22017784. Unknown parameter
|month=ignored (help) - ↑ Oren, RM. (2005). "Hyponatremia in congestive heart failure". Am J Cardiol. 95 (9A): 2B–7B. doi:10.1016/j.amjcard.2005.03.002. PMID 15847851. Unknown parameter
|month=ignored (help)