Hypernatremia is an electrolyte disorder defined as an increase in plasma sodium concentration greater than 145 mEq/L, always results in hypertonicity (hyperosmolality), and usually occurs due to lack of water, loss of water, or primary sodium gain [1, 2].

Hypernatremia is a less frequent disorder (about 1%–3% of all hospitalized patients and 9% in critically ill patients) but carries significantly higher mortality (about 40–60%) [3–5].

HYPERNATREMIA IS USUALLY DUE TO WATER DEFICIT AND NOT SODIUM OVERLOAD.

Normal thirst is the most potent mechanism that effectively prevents hypernatremia. So, hypernatremia usually does not occur in healthy adults who can respond to thirst unless there is non-availability of water, restricted water intake, impaired thirst, or the patient cannot drink the water due to a comatose-confused state. Therefore, hypernatremia is seen chiefly in very young, very old, very sick, bed-ridden, or debilitated patients. A pure water deficit leading to hypernatremia is called dehydration.

Common causes of hypernatremia classified based on volume status, water loss or salt gain, urinary sodium, and underlying etiologies are summarized in Table 21.1.

REFERENCES

1. Adrogué HJ, Madias NE. Hypernatremia. N Engl J Med. 2000;342(20):1493–9.
2. Sterns RH. Disorders of plasma sodium--causes, consequences, and correction. N Engl J Med 2015;372(1):55–65.
3. Palevsky PM, Bhagrath R, Greenberg A. Hypernatremia in hospitalized patients. Ann Intern Med. 1996;124(2):197–203.
4. Funk GC, Lindner G, Druml W, et al. Incidence and prognosis of dysnatremias present on ICU admission. Intensive Care Med. 2010;36(2):304–11.
5. Muhsin SA, Mount DB. Diagnosis and treatment of hypernatremia. Best Pract Res Clin Endocrinol Metab. 2016;30(2):189–203.
6. Kim SW. Hypernatemia: successful treatment. Electrolyte Blood Press. 2006;4(2):66–71.
7. Braun MM, Barstow CH, Pyzocha NJ. Diagnosis and management of sodium disorders: hyponatremia and hypernatremia. Am Fam Physician. 2015;91(5):299–307.
8. Jessica MAA, Astrid CBG, Anusha K, et al. Management of Nephrogenic Diabetes Insipidus: An Overview. JOJ Urology & Nephrology. 2022;7(5):555722.
9. Lodin M, Dwyer J. The role of amiloride in managing patients with lithium-induced nephrogenic diabetes insipidus Journal of Pharmacy Practice and Research 2017;47(5):389–392.
10. Danilo CR. Use of amiloride in lithium-induced nephrogenic diabetes insipidus. J Anal Pharm Res. 2018;7(3):286–287.
11. Mortensen LA, Bistrup C, Jensen BL, et al. A mini-review of pharmacological strategies used to ameliorate polyuria associated with X-linked nephrogenic diabetes insipidus. Am J Physiol Renal Physiol. 2020;319(5):F746–F753.
12. Nguyen MK, Kurtz I. Correction of hypervolaemic hypernatremia by inducing negative Na+ and K+ balance in excess of negative water balance: a new quantitative approach. Nephrol Dial Transplant. 2008;23(7):2223–7.
13. Morkos M, Fam M, Goel M, et al. Protracted acute hypervolemic hypernatremia unmasked after vasopressin therapy: case report, literature review, and proposed algorithmic approach. AACE Clin Case Rep. 2018;5(2):95–98.
14. Pazmiño PA, Pazmiño BP. Treatment of acute hypernatremia with hemodialysis. Am J Nephrol. 1993;13(4):260–265.
15. Nur S, Khan Y, Nur S, et al. Hypernatremia: correction rate and hemodialysis. Case Rep Med. 2014;2014:736073.
16. Rondon-Berrios H, Argyropoulos C, Ing TS, et al. Hypertonicity: Clinical entities, manifestations and treatment. World J Nephrol 2017;6(1):1–13.
17. Sterns RH, Silver SM. Salt and water: read the package insert. QJM. 2003;96(8):549–52.
18. Carlberg DJ, Borek HA, Syverud SA, et al. Survival of acute hypernatremia due to massive soy sauce ingestion. J Emerg Med 2013;45(2):228–31.
19. Farkas J. Hypernatremia & Dehydration in the ICU. IBCC [Internet]. June 25, 2021. Available from: https://emcrit.org/ibcc/hypernatremia/.
20. Bolat F, Oflaz MB, Güven AS, et al. What is the safe approach for neonatal hypernatremic dehydration? A retrospective study from a neonatal intensive care unit. Pediatr Emerg Care 2013;29(7):808–13.
21. Alshayeb HM, Showkat A, Babar F, et al. Severe hypernatremia correction rate and mortality in hospitalized patients. Am J Med Sci. 2011;341(5):356–60.
22. Bataille S, Baralla C, Torro D, et al. Under correction of hypernatremia is frequent and associated with mortality. BMC Nephrol. 2014;15:37.
23. Bohlouli B, Jackson TJ, Tonelli M, et al. Adverse outcomes associated with preventable complications in hospitalized patients with CKD. Clin J Am Soc Nephrol. 2017;12(5):799–806.
24. Ryu JY, Yoon S, Lee J, et al. Efficacy and safety of rapid intermittent bolus compared with slow continuous infusion in patients with severe hypernatremia (SALSA II trial): a study protocol for a randomized controlled trial. Kidney Res Clin Pract. 2022;41(4):508–520.
25. Chauhan K, Pattharanitima P, Patel N, et al. Rate of Correction of Hypernatremia and Health Outcomes in Critically Ill Patients. Clin J Am Soc Nephrol 2019;14(5):656–663.
26. Feigin E, Feigin L, Ingbir M, et al. Rate of Correction and All-Cause Mortality in Patients With Severe Hypernatremia. JAMA Netw Open. 2023;6(9):e2335415.
27. Lindner G, Schwarz C, Kneidinger N, et al. Can we really predict the change in serum sodium levels? An analysis of currently proposed formulae in hypernatremic patients. Nephrol Dial Transplant. 2008;23(11):3501–8.
28. Sterns RH. Formulas for fixing serum sodium: curb your enthusiasm. Clin Kidney J 2016;9(4):527–9.