Hyponatremia is a common electrolyte disorder1
Hyponatremia is a common electrolyte disorder that occurs in up to 30% of all hospitalized patients.1,2 The disorder is important to recognize because it can have serious clinical consequences.3
Hyponatremia can be defined by:
- Serum sodium concentration4 <135 mEq/L
- Disorder of water balance
- Body water is in excess relative to total body sodium5
Types of Hyponatremia
Hyponatremia can be classified by several clinical parameters, and treatment strategies are often based on a combination of these parameters.5
Incidence of hyponatremia is high
in hospitalized patients6
Using the definition of serum sodium <135 mEq/L, reported incidences of hyponatremia in both acutely and chronically hospitalized patients have been as high as 15 to 30%.6
Etiology & Pathogenesis
Hypotonic hyponatremia has multiple etiologies5,7,8
Etiologies can be categorized under the 3 main volume statuses: hypovolemic hyponatremia, euvolemic hyponatremia, and hypervolemic hyponatremia. Laboratory data and a physical exam will help assess patients’ volume status. The volume status will help determine the etiology of the hyponatremia.5,7,8
Hypotonic hyponatremia typically results from a
disruption in the excretion of water from the kidneys
This disruption in the excretion of water from the kidneys results in water retention, and is usually due to vasopressin release or renal failure.9
Symptoms & Risks
Hyponatremia can result in poor patient outcomes due to the following complications and risks:
Hyponatremia signs and symptoms can range from
mild or nonspecific to severe
Nonspecific or mild symptoms of hyponatremia can progress quickly to severe symptoms. The more severe symptoms are often neurologic complications due to brain edema and increased intracranial pressure from severe and rapidly evolving hyponatremia3,6,10
Impact on Hospitals
Hyponatremia results in longer, more costly
results in an increased length of hospital stay that is strongly associated with the severity of hospital-acquired hyponatremia10
Hyponatremia on admission
results in longer,17 more costly hospital stays, with the costliest stays occurring in the more severe cases of hyponatremia17
Both hyponatremia on admission and
result in greater utilization of health care resources, and an increase in ICU admissions and hospital readmissions.18
There are several different methods that physicians use to treat hyponatremia
Hyponatremia treatment approach depends on
Criteria used in the treatment approach for hyponatremia depends on the rate of onset (acute or chronic) of hyponatremia,
the symptom status, and the volume status.6,10
- Hawkins RC. Age and gender as risk factors for hyponatremia and hypernatremia. Clin Chim Acta. 2003;337(1-2):169-172.
- Upadhyay A, Jaber BL, Madias NE. Incidence and prevalence of hyponatremia. Am J Med. 2006;119(7 Suppl 1):S30-S35.
- Adrogué HJ, Madias NE. The challenge of hyponatremia. J Am Soc Nephrol. 2012;23(7):1140-1148.
- Vaidya C, Ho W, Freda BJ. Management of hyponatremia: providing treatment and avoiding harm. Cleve Clin J Med. 2010;77(10):715-726. doi:10.3949/ccjm.77a.08051.
- Douglas I. Hyponatremia: why it matters, how it presents, how we can manage it. Cleve Clin J Med. 2006;73(Suppl 3):S4-S12.
- Verbalis JG, Goldsmith SR, Greenberg A, et al. Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. Am J Med. 2013;126(10 Suppl 1):S1-S42. doi:10.1016/j.amjmed.2013.07.006.
- Assadi F. Hyponatremia: a problem-solving approach to clinical cases. J Nephrol. 2012; 25(4):473-380. doi:10.5301/jn.5000060.
- Sra J, Repp AB. Hyponatremia. Hosp Med Clin. 2012;1:e199-e208. doi:10.1016/j.ehmc.2012.03.007.
- Rudolph EH, Pendergraft WF, Lerma EV. Common electrolyte disorders: hyponatremia. Hosp Physician. 2009;48:23-32.
- Adrogué HJ, Madias NE. Hyponatremia. N Engl Med. 2000;343(21):1581-1589.
- Arieff AI, Guisado R. Effects on the central nervous system of hypernatremia and hyponatremic states. Kidney Int. 1976;10(1):104-116.
- Wald R, Jaber BL, Price LL, Upadhyay A, Madias NE. Impact of hospital-associated hyponatremia on selected outcomes. Arch Intern Med. 2010;170(3):294-302. doi: 10.1001/archintemmed.2009.513.
- Kinsella S, Moran S, Sullivan MO, Molloy MG, Eustace JA. Hyponatremia independent of osteoporosis is associated with fracture occurrence. Clin J Am Soc Nephrol. 2010;5(2):275-280. doi:10.2215/CJN.06120809.
- Gankam Kengne F, Andres C, Sattar L, Melot S, Decaux G. Mild hyponatremia and risk of frature in the ambulatory elderly.QJM. 2008;101(7):583-588. doi:10:1093/qjmed/hcn061.
- Renneboog B, Musch W, Vandemergel X, Manto MU, Decaux G. Mild chronic hyponatremia is associated with falls, unsteadiness, and attention deficits. Am J Med. 2006;119(1):71.e1-71.e8. doi:10.1016/j.amjmed.2005.09.026.
- Verbalis JG, Barsony J, Sugimura Y, et al. Hyponatremia-induced osteoporosis. J Bone Miner Res. 2010;25(3):554-563. doi:10.1359/jbmr.090827.
- Callahan MA, Do HT, Caplan DW, Yoon-Flannery K. Economic impact of hyponatremia in hospitalized patients: a retrospective cohort study. Postgrad Med. 2009;121(2):186-191.
- Deitelzweig S, Amin A, Christian R, Friend K, Lin J, Lowe TJ. Health care utilization, costs, and readmission rates associated with hyponatremia. Hosp Pract (1985). 2013; 41(1): 89-95.
- Goldsmith SR. Current treatments and novel pharmacologic treatments for hyponatremia in congestive heart failure. Am J Cardiol. 2005;95(9A):14B-23B.