Hypernatraemia

Serum sodium concentration

Hypernatraemia is defined as a serum sodium concentration of >145 mmol/L.[1]Braun MM, Barstow CH, Pyzocha NJ. Diagnosis and management of sodium disorders: hyponatremia and hypernatremia. Am Fam Physician. 2015 Mar 1;91(5):299-307. https://www.aafp.org/afp/2015/0301/p299.html http://www.ncbi.nlm.nih.gov/pubmed/25822386?tool=bestpractice.com ​ Severe hypernatraemia has variously been defined as a serum sodium concentration of >152 mmol/L, >155 mmol/L, or >160 mmol/L.[2]Sam R, Ing TS. Sodium and water disturbances. In: Lai KN, ed. A practical manual of renal medicine, nephrology, dialysis and transplantation. Singapore: World Scientific Publishing C.; 2009:45-79.[3]Nur S, Khan Y, Nur S, et al. Hypernatremia: correction rate and hemodialysis. Case Rep Med. 2014;2014:736073. https://www.hindawi.com/journals/crim/2014/736073 http://www.ncbi.nlm.nih.gov/pubmed/25431600?tool=bestpractice.com [4]Cabassi A, Tedeschi S. Severity of community acquired hypernatremia is an independent predictor of mortality: a matter of water balance and rate of correction. Intern Emerg Med. 2017 Jul 1;12(7):909-11. http://www.ncbi.nlm.nih.gov/pubmed/28669048?tool=bestpractice.com However,​ no consensus has been reached on the exact level.

Time of onset

Patients with hypernatraemia that has developed slowly (e.g., over days, weeks, or months) are commonly asymptomatic, while patients with hypernatraemia that has developed rapidly (e.g., over a few hours) will be symptomatic. Hypernatraemia that develops in <48 hours is usually classified as acute, while hypernatraemia that develops over ≥48 hours is chronic.