Hyponatremia in Older Adults: Diagnosis
Sangeetha Murugapandian, M.D. and Bijin Thajudeen, M.D.; Department of Medicine, University of Arizona
|TIPS ABOUT HYPONATREMIA IN OLDER ADULTS|
Hyponatremia, defined as serum sodium level less than 135mEq/L, is one of the most common electrolyte abnormalities seen in older adults. In one study, more than 50% of patients in acute geriatric wards were found to have hyponatremia. Chronic hyponatremia has been reported in 18% of nursing home residents.
Why is the Prevalence Increased in Older Adults?
A number of factors contribute to the high prevalence of hyponatremia in older adults (Table 1.)
|Table 1. Factors Contributing to the Increased Prevalence of Hyponatremia in Older Adults|
Why is Hyponatremia Important?
Long-standing or slowly developing chronic hyponatremia may be asymptomatic but is associated with increased osteoclastic activity leading to bone demineralization and fractures. Symptoms of acute hyponatremia vary depending on the degree of hyponatremia and rapidity with which it develops (Table 2). Those with severe acute hyponatremia can develop cerebral edema. Less severe cases are associated with confusion, functional and cognitive decline, and gait disturbances that can lead to falls. Patients with hyponatremia also have increased mortality rates and longer hospitalizations.
Table 2. Common Clinical Manifestations of Acute Hyponatremia
Mild (Sodium Level 130-134 mEq/L)
Moderate (Sodium Level 125-129 mEq/L)
Severe (Sodium Level <125 mEq/L)
What Causes Hyponatremia?
Depending on a patient’s volume status, hyponatremia is classified hypovolemic (low fluid volume status), euvolemic (normal volume status) or hypervolemic (increased volume status). Common causes of each of these forms of hyponatremia are shown in Table 3, but in older adults, the cause is often multifactorial. The algorithm and the items in Table 4 show the general approach to identifying the cause.
|Table 3. Common Causes of Hyponatremia|
Table 4. Components of the History and Physical in Older Adults with Hyponatremia to Aid in Identifying the Cause
Review Hospital Records
Use of hypotonic fluids, medications, surgical history, pain assessment, recent interventions (transurethral resection of prostate, use of hypertonic fluids)
Vomiting, diarrhea, heart failure, pulmonary disease, liver disease, renal failure, thyroid, neurological disorders, falls, cognitive impairment, adrenal disorders
Diuretics, SSRIs, neuroleptics (anti-psychotics), carbamazepine, and amiodarone are common causes. But, check prescribing information for all medication a patient is taking to determine potential to cause hyponatremia.
Living conditions, diet, alcohol
Abnormal water intake
Assessment of Volume Status
Signs of hypervolemia = peripheral edema, pulmonary rales
Signs of hypovolemia = orthostatic hypotension, tachycardia, dry axillae
References and Resources
- Al Zahrani, Sinnerty R, Gernsheimer J. . Acute kidney Injury, sodium disorders, and hypercalcemia in the aging kidney: diagnostic and therapeutic management strategies in emergency medicine Clin Geriatr Med, 2013; 29:275-319.
- Choudhury D, Levi M. Aging and Kidney Disease. In: Skorecki K, Chertow GM, et al . Eds. Brenner and Rector’s The Kidney, 24, 727-751. 2
- Murugapandian S, Thajudeen B. Hyponatremia in Older Adults – Therapeutic Considerations. Elder Care, 2017.
- Soiza RL, Cumming K, Clarke JM, Wood KM, Myint PK. Hyponatremia: special considerations in older patients. J Clin Med. 2014;3(3):944-958.