Title:Hyponatraemia: An Audit of Aged Psychiatry Patients Taking SSRIs and SNRIs
VOLUME: 8 ISSUE: 3
Author(s):Francesco Giorlando, Julia Teister, Seetal Dodd, Marc Udina and Michael Berk
Affiliation:29 Chestnut St., Cremorne VIC 3121, Australia.
Keywords:Hyponatraemia, Major Depression, SNRI, sodium, SSRI.
Abstract:Objective: Hyponatraemia is a serious adverse event commonly reported in elderly people treated with
serotonergic antidepressants. The mechanism, incidence and risk factors for antidepressant induced hyponatraemia are not
fully understood.
Method: In a retrospective chart analysis, depressed patients aged >63 years were investigated for change in serum sodium
levels between two time points, separated by a median period of 45.5 days, with the first specimen taken prior to
treatment. Patients were grouped into three cohorts; treated with an SSRI or SNRI (n=77), treated with an antidepressant
other than an SSRI or SNRI (n=54) and not treated with an antidepressant (n=128).
Results: For change in sodium level between measurements and total number of patients with hyponatraemia, there was
no significant difference between cohorts. However, the rate of reduction of serum sodium levels between time points was
significantly greater for SSRI and SNRI treated patients (p<0.001) and patients treated with other antidepressants (p=0.03)
compared to patients not treated with antidepressants. Moreover, the distribution of values of change in serum sodium was
skewed towards reduced serum sodium in patients treated with SSRI or SNRIs (skew -0.43) and patients treated with
other antidepressants (skew -0.09) but not for patients without antidepressants (skew 0.25).
Conclusions: These data suggest that antidepressant treatment is associated with hyponatraemia affecting a subgroup of
individuals only. Generalised linear modelling showed that the risk of hyponatraemia increases with increased age, female
gender, and particularly the antidepressant agents sertraline and escitalopram. The findings are of clinical significance as
they demonstrate that hyponatraemia can occur rapidly with antidepressants, and SSRI/SNRI medications induce more
rapid changes. They support the use of electrolyte monitoring early in antidepressant treatment in patients receiving
antidepressants.
