Hyponatremia is the most common electrolyte imbalance found in clinical practice, affecting approximately 1.72 percent of the US population. The condition refers to a low concentration of sodium in the blood, falling below 135 mmol/l. Hypernatremia – the opposite condition to hyponatremia – is associated with high sodium levels, exceeding 145 mmol/l.
Hyponatremia is often found in patients with multiple co-morbidities, such as diseases that impact the vital organs. This makes it more common in elderly people and hospitalised patients; in fact, hyponatremia affects up to 30 percent of patients in hospital and is associated with increased morbidity and mortality. The condition has been reported to delay surgery, prolong post-surgical recovery, and increase hospital readmissions.
A serious condition
As well as long term health conditions, hyponatremia and hypernatremia can be triggered by excessive consumption of water or dehydration respectively. Both conditions can also be caused by changes in medication that cause the retention of, or expulsion of liquid. Mild versions of hyponatremia can cause confusion or sluggishness, irritability, restlessness or nausea. More severe cases can lead to vomiting and seizures. The condition can ultimately cause an altered mental state, seizures, a coma or death.
Interfering with surgery
Hypernatremia is associated with increased risk of venous thromboembolisms (VTEs) – life-threatening blood clots, typically in the deep veins of the leg, that can lead to a pulmonary embolism. VTE risk increases up to 100-fold in hospitalised patients compared to the general population: it is the leading cause of death and disability in hospital. Elderly and critically ill patients undergoing surgery are already at risk of developing VTE due to a lack of mobility during recovery; those with high sodium levels are at an even higher exposure.
The risk of in hospital VTE increases with age, particularly among those older than 65. Around one third of adults older than 65 and half of those older than 80 will fall at least once every year. Falls can cause fractures and breaks in older, more brittle bones. According to a study by Bergh et al entitled ‘Fracture incidence in adults in relation to age and gender: A study of 27,169 fractures in the Swedish Fracture Register in a well-defined catchment area,’ the mean age for fragility fractures was above 63 years (both genders combined). Hip fractures are especially common among the elderly with more than 95 percent of hip fractures caused by falling.
Surgery is the preferred treatment option for most fractures, and the National Institute for Health and Care Excellence (NICE) recommends that surgical intervention occurs within 48 hours of admission to hospital with a fracture. Patients must have stabilised sodium levels for surgery to proceed and it may need to be delayed if the patient displays symptoms of a sodium imbalance.
Identifying the risks
As well as potentially leading to delays in surgery, immobile patients become increasingly at risk of VTE as they wait for the appropriate sodium levels to be achieved. Healthcare prof