LAB MANAGEMENT :: HYPONATREMIA OUTCOMES


Shining renewed light on a tried-and- true test: The critical role of osmolality in improving health outcomes in patients with hyponatremia


Julie MacKenzie, MBA H


yponatremia, defined as a serum sodium concentration of ≤135 mEq/L, is the most common elec-


trolyte disorder encountered in clini- cal practice, occurring in up to 30% of hospitalized patients.1


The prevalence


of hyponatremia is conservatively esti- mated to range from 3.2 million to 6.1 million people in the United States on an annual basis. Most patients treated for hyponatremia are initially treated as inpatients (55%–63%), 25% are ini- tially treated in the emergency room, and 13%–20% are exclusively treated in the office setting. See Figure 1 for key statistics.


Hyponatremia is often observed at admission but also frequently develops during hospitalization either as a com- plication of an underlying illness or as the result of therapeutic interventions.8 High incidences of hyponatremia have been reported in a variety of patient populations including those with heart failure,9,10


cancer,14,15,16


renal disease,11,12 pneumonia,17


cirrhosis,13 and stroke.18,19


Hyponatremia also frequently occurs after various surgical procedures in-


Key Statistics • Hyponatremia occurs in up to 30% of hospitalized patients1


• 47% increased risk of death in-hospital at 1 year associated with hyponatremia2


• Increase of 2 days in mean length of stay associated with hyponatremia3


• Increase of ~50% in the odds of having a 30-day unplanned readmis- sion or death associated with hyponatremia4


• Reduction in overall mortality of 60% with hyponatremia correction5


• $1.14 billion in potentially avoidable costs associated with electrolyte disorders in the U.S.6


• Osmolality and sodium measured in only 23% of patients with hyponatremia7


Figure 1. 36 DECEMBER 2022 MLO-ONLINE.COM


Photo courtesy of Advanced Instruments, LLC


cluding pelvic,20 surgery.22,23


spinal,21 and pituitary


the elderly, in part because of age-related decline in renal function.24,25


It is particularly prevalent in Addition-


ally, patients who receive maintenance intravenous fluids, particularly children,


are in danger of developing hyponatre- mia.26,27


Hyponatremia is also common


with COVID-19, occurring in nearly a third of hospitalized patients.28,29


Association of hyponatremia with poor outcomes Numerous studies have demonstrated the association between hyponatremia and poor outcomes across diverse patient pop- ulations.30,31,32,33


Winzeler et al. conducted


a prospective observational 12-month fol- low-up study of 281 patients with profound hyponatremia (<125 mmol/L). During the follow-up period, 20.6% of patients died, 56.2% were rehospitalized at least once, and 42.7% had recurrent hyponatremia. However, it is not just severe hyponatre- mia that has been associated with adverse outcomes. Both mild (130–135 mmol/L) and moderate (125–129 mmol/L) hypo- natremia have also been associated with unfavorable outcomes in the literature.2,34 In a meta-analysis of 81 published studies encompassing 850,222 patients, Corona et al. demonstrated that moderate hypona- tremia is associated with an increased risk of mortality, and that it is a negative prognostic factor across multiple com-


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