What does the evidence indicate regarding theepidemiology of hypernatremia?

Hypernatremia is a common and often severe electrolyte disorder, with the highest prevalence in the elderly and the debilitated. Studies have shown that the incidence of hypernatremia in hospitalized patients ranges somewhere between 0.3% and 5.5%.9’10 A large cohort study of 15,187 newly hospitalized patients older than 60 years of age calculated the incidence rate of hypernatremia to be 1.1%, with 43% of patients hypernatremic on admission and the remaining 57% developing hypernatremia post-admission. A large percentage of the patients who ultimately developed hypernatremia post-admission showed rapid onset, with 50% of patients developing hypernatremia within the first 8 days of admission.11 While the study identified more than 40 causal factors of hypernatremia, the most frequent primary causes were complications of recent surgery (21%), febrile illness (20%), infirmity (11%), and diabetes mellitus (11%).11

A more recent prospective cohort study of general medical-surgcal patients showed that the prevalence of hypernatremia was 1% of patients at risk (n = 8517).12 This study went on to show that the prevalence of hospital-associated hypernatremia has an age distribution that parallels the age distribution of hospitalized patients. This implies that hospital-acquired hypernatremia affects patients of various ages, often as the result of inappropriate intravenous fluid prescriptions.

In the intensive care unit, dysnatremias are even more prevalent than in the general patient wards. Two earlier studies found a hypernatremia prevalence rate of ~9% in patients hospitalized in the ICU13-14. A more recent study demonstrated an incidence rate of 7.4% per 100 days of ICU admission,15 underscoring the importance of the need for physicians to be familiar with the management of this common but complex disorder.

Bottom Line: Hypernatremia has a prevalence of approximately

0.3%-5.5% depending on the population studied. Hypernatremia in hospitalized patients has an age of distribution similar to that of the overall population. This differs from outpatient hypernatremia, which more often affects the elderly.

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