What are the mortality rates for hypernatremia?

Updated: Mar 17, 2020
  • Author: Zina Semenovskaya, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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The mortality rate from hypernatremia is high, especially among elderly patients. Mortality rates of 42-75% have been reported for acutely evolving hypernatremia and 10-60% for chronic hypernatremia. Because patients with hypernatremia often have other serious comorbidities, precisely evaluating the degree of mortality directly due to hypernatremia is difficult. Morbidity in survivors is high, with many patients experiencing permanent neurologic deficits.

Most deaths are due to an underlying disease process, rather than the hypernatremia itself. Delay in treatment (or inadequate treatment) of hypernatremia increase mortality.

A study by Vedantam et al reported that in patients with severe traumatic brain injury (TBI), an independent association exists between the development of hypernatremia after hospital admission, whether mild, moderate, or severe, and an increased likelihood of early mortality. The investigators cited mortality hazard ratios for mild, moderate, and severe hypernatremia of 3.4, 4.4, and 8.4, respectively, in severe TBI. [5]

A study by Huang et al indicated that in patients with chronic kidney disease, hypernatremia is associated with an increased risk for all-cause mortality and for deaths unrelated to cardiovascular problems or malignancy. Hyponatremia was found to be associated with an increased risk for the same, as well as for cardiovascular- and malignancy-related mortality. The study included 45,333 patients with stage 3 or 4 chronic kidney disease, 9.2% of whom had dysnatremia. [6]

A Turkish study, by Ates et al, indicated that in patients presenting to emergency departments with severe hypernatremia, independent risk factors for mortality included low systolic blood pressure, low pH, Na+ level over 166 mmol/L, increased plasma osmolarity, a mean sodium reduction rate of -0.134 mmol/L/h or less, dehydration, and, pneumonia. The retrospective study included 256 patients. [7]

In hospitalized patients, persistent hypernatremia and protracted hypotension have been associated with a very poor prognosis. A study by Jung et al indicated that in patients with community-acquired hypernatremia, an independent association exists between admission to the hospital from the emergency department and hospital mortality, with the same being true for oral intake restriction, mean arterial pressure, and respiratory rate. Also with regard to hospital mortality, multivariate analysis revealed a peak sodium level in the moderate or severe range to be an independent risk factor. [8]

The aforementioned study by Giordano et al stated that the great majority of electrolyte imbalances encountered in the report were associated with other systemic diseases. Dividing the study population into young, middle aged, and elderly, the investigators found that in the young group, electrolyte imbalances were most commonly associated with gastrointestinal disease, while in the middle-aged group, they were most often associated with cardiovascular disease, and in the elderly group, with cardiovascular disorders and lung disease. [4]

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