Question: In adults commencing or maintaining antidepressants, what is the risk of developing hyponatremia/hyponatraemia? Are there any recommendations for best practice?

Answer:

No definite clinical implications can be made from the available evidence. There is, however, consistent evidence that selective serotonin reuptake inhibitors (SSRIs) are associated with an increased risk of developing hyponatraemia in depressed elderly adults, but there is inconsistency in the incidence (or prevalence) between studies. Due to methodological shortcomings in the evidence, and the lack of head to head studies, it is not possible to determine which antidepressants may be best to use in clinical practice.

Common recommendations were suggested:

1) Monitoring of sodium concentrations in elderly patients prescribed a SSRI or a serotonin-norepinephrine reuptake inhibitor (SNRI) should be done - including before, and 1 to 2 weeks after, initiating treatment. This is especially important for patients who present with additional risk factors such as female sex, low BMI, baseline plasma sodium level of 138 mEq/L or less, or patients with comorbid medical illness or concomitant medications known to alter ADH or cause hyponatraemia (e.g. diuretics).

2) A sodium level should be obtained in all elderly patients who exhibit abrupt changes in mental status (e.g. lethargy, confusion) any time during treatment with an SSRI.

Many authors recommended that further research, including long-term randomised controlled trials, are needed to compare the benefits and risks of different anti-depressants in elderly people with depression. More research is also needed to assess the association between antidepressants and hyponatraemia in different age groups.

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To view relevant national guidelines, click Related Links, below.