Evaluation of hypernatremia

Hypernatremia is defined as a plasma sodium concentration of >145 mEq/L.

Hypernatremia is a state of hyperosmolality, and is primarily a result of water deficit or, rarely, sodium gain. Due to the maintenance of osmotic equilibrium, intracellular fluid (ICF) becomes volume contracted. The appropriate responses are increased water intake stimulated by thirst, and the excretion of the minimal amount of maximally concentrated urine.

Infants, and adults with cognitive impairment, are commonly affected because of their inability to express thirst and limited access to water.

Hypernatremia is often the result of several disease processes, and the underlying cause needs to be elicited to correct the sodium balance. The physical consequences of hypernatremia can be severe, and overlap with many of the precipitating causes.

Epidemiology

Hypernatremia generally occurs in patients at extremes of age, or in those who are physically or cognitively debilitated.[1]Brennan M, Mulkerrin L, O'Keeffe ST, et al. Approach to the management of hypernatraemia in older hospitalised patients. J Nutr Health Aging. 2021;25(10):1161-6. https://pmc.ncbi.nlm.nih.gov/articles/PMC12275548 http://www.ncbi.nlm.nih.gov/pubmed/34866143?tool=bestpractice.com [2]Molaschi M, Ponzetto M, Massaia M, et al. Hypernatremic dehydration in the elderly on admission to hospital. J Nutr Health Aging. 1997;1(3):156-60. http://www.ncbi.nlm.nih.gov/pubmed/10995084?tool=bestpractice.com [3]Tomkins M, Mc Donald D, Green D, et al. Diagnosis and treatment of hypernatremia. Best Pract Res Clin Endocrinol Metab. 2026 Jan;40(1):102065. http://www.ncbi.nlm.nih.gov/pubmed/41203493?tool=bestpractice.com

Hospital-acquired hypernatremia is the most common form of hypernatremia; it is iatrogenic in some cases.[4]Tsipotis E, Price LL, Jaber BL, et al. Hospital-associated hypernatremia spectrum and clinical outcomes in an unselected cohort. Am J Med. 2018 Jan;131(1):72-82.e1. http://www.ncbi.nlm.nih.gov/pubmed/28860033?tool=bestpractice.com [5]Thongprayoon C, Cheungpasitporn W, Yap JQ, et al. Increased mortality risk associated with serum sodium variations and borderline hypo- and hypernatremia in hospitalized adults. Nephrol Dial Transplant. 2020 Oct 1;35(10):1746-52. https://academic.oup.com/ndt/article/35/10/1746/5521070 http://www.ncbi.nlm.nih.gov/pubmed/31219584?tool=bestpractice.com [6]Ranjan R, Lo SC, Ly S, et al. Progression to severe hypernatremia in hospitalized general medicine inpatients: an observational study of hospital-acquired hypernatremia. Medicina (Kaunas). 2020 Jul 17;56(7):358. https://www.mdpi.com/1648-9144/56/7/358 http://www.ncbi.nlm.nih.gov/pubmed/32709029?tool=bestpractice.com [7]Arzhan S, Roumelioti ME, Litvinovich I, et al. Hypernatremia in hospitalized patients: a large population-based study. Kidney360. 2022 Jul 28;3(7):1144-57. https://journals.lww.com/kidney360/Fulltext/2022/07000/Hypernatremia_in_Hospitalized_Patients__A_Large.8.aspx http://www.ncbi.nlm.nih.gov/pubmed/35919520?tool=bestpractice.com Discharge data from unselected hospitalized patients suggest that hospital-acquired hypernatremia may develop in up to 26% of patients.[4]Tsipotis E, Price LL, Jaber BL, et al. Hospital-associated hypernatremia spectrum and clinical outcomes in an unselected cohort. Am J Med. 2018 Jan;131(1):72-82.e1. http://www.ncbi.nlm.nih.gov/pubmed/28860033?tool=bestpractice.com Hypernatremia that is present on admission to the hospital is less common (e.g., 3% to 21%).[4]Tsipotis E, Price LL, Jaber BL, et al. Hospital-associated hypernatremia spectrum and clinical outcomes in an unselected cohort. Am J Med. 2018 Jan;131(1):72-82.e1. http://www.ncbi.nlm.nih.gov/pubmed/28860033?tool=bestpractice.com [7]Arzhan S, Roumelioti ME, Litvinovich I, et al. Hypernatremia in hospitalized patients: a large population-based study. Kidney360. 2022 Jul 28;3(7):1144-57. https://journals.lww.com/kidney360/Fulltext/2022/07000/Hypernatremia_in_Hospitalized_Patients__A_Large.8.aspx http://www.ncbi.nlm.nih.gov/pubmed/35919520?tool=bestpractice.com

Mortality rates range between 20% and 60% for all patients.[1]Brennan M, Mulkerrin L, O'Keeffe ST, et al. Approach to the management of hypernatraemia in older hospitalised patients. J Nutr Health Aging. 2021;25(10):1161-6. https://pmc.ncbi.nlm.nih.gov/articles/PMC12275548 http://www.ncbi.nlm.nih.gov/pubmed/34866143?tool=bestpractice.com [3]Tomkins M, Mc Donald D, Green D, et al. Diagnosis and treatment of hypernatremia. Best Pract Res Clin Endocrinol Metab. 2026 Jan;40(1):102065. http://www.ncbi.nlm.nih.gov/pubmed/41203493?tool=bestpractice.com [8]Muhsin SA, Mount DB. Diagnosis and treatment of hypernatremia. Best Pract Res Clin Endocrinol Metab. 2016 Mar;30(2):189-203. https://www.sciencedirect.com/science/article/abs/pii/S1521690X16000415?via%3Dihub http://www.ncbi.nlm.nih.gov/pubmed/27156758?tool=bestpractice.com Hospital-acquired hypernatremia, severe hypernatremia, critical illness, older age, and comorbid conditions are associated with worse prognosis.[1]Brennan M, Mulkerrin L, O'Keeffe ST, et al. Approach to the management of hypernatraemia in older hospitalised patients. J Nutr Health Aging. 2021;25(10):1161-6. https://pmc.ncbi.nlm.nih.gov/articles/PMC12275548 http://www.ncbi.nlm.nih.gov/pubmed/34866143?tool=bestpractice.com [4]Tsipotis E, Price LL, Jaber BL, et al. Hospital-associated hypernatremia spectrum and clinical outcomes in an unselected cohort. Am J Med. 2018 Jan;131(1):72-82.e1. http://www.ncbi.nlm.nih.gov/pubmed/28860033?tool=bestpractice.com [5]Thongprayoon C, Cheungpasitporn W, Yap JQ, et al. Increased mortality risk associated with serum sodium variations and borderline hypo- and hypernatremia in hospitalized adults. Nephrol Dial Transplant. 2020 Oct 1;35(10):1746-52. https://academic.oup.com/ndt/article/35/10/1746/5521070 http://www.ncbi.nlm.nih.gov/pubmed/31219584?tool=bestpractice.com [6]Ranjan R, Lo SC, Ly S, et al. Progression to severe hypernatremia in hospitalized general medicine inpatients: an observational study of hospital-acquired hypernatremia. Medicina (Kaunas). 2020 Jul 17;56(7):358. https://www.mdpi.com/1648-9144/56/7/358 http://www.ncbi.nlm.nih.gov/pubmed/32709029?tool=bestpractice.com [9]Thongprayoon C, Mao MA, Keddis MT, et al. Hypernatremia subgroups among hospitalized patients by machine learning consensus clustering with different patient survival. J Nephrol. 2022 Apr;35(3):921-9. http://www.ncbi.nlm.nih.gov/pubmed/34623631?tool=bestpractice.com [10]Yun G, Baek SH, Kim S. Evaluation and management of hypernatremia in adults: clinical perspectives. Korean J Intern Med. 2023 May;38(3):290-302. https://pmc.ncbi.nlm.nih.gov/articles/PMC10175862 http://www.ncbi.nlm.nih.gov/pubmed/36578134?tool=bestpractice.com

Hypernatremia is diagnosed in males and females in equal numbers.