Delayed recurrent SIADH associated with SSRIs.
BACKGROUND
Depression is a common problem in elderly patients and is frequently treated with selective serotonin-reuptake inhibitors (SSRIs).


OBJECTIVE
To report a case of delayed recurrent hyponatremia after switching from one SSRI to another.


METHODS
An 87-year-old depressed woman began treatment with fluvoxamine. One week later, she was diagnosed with hyponatremia, most likely syndrome of inadequate antidiuretic hormone. Following discontinuation of fluvoxamine, the serum sodium concentration normalized. Later, she began treatment with paroxetine. Sixteen months after initiating paroxetine, she developed symptomatic recurrent hyponatremia. After paroxetine was discontinued, the sodium concentration normalized.


CONCLUSIONS
In this case, unlike those previously reported, hyponatremia recurred 16 months after a different SSRI was initiated. The Naranjo probability scale indicates a probable relationship between recurrent hyponatremia and paroxetine. The mechanism of SSRI-induced hyponatremia is multifactorial.


CONCLUSIONS
This case illustrates that replacement of one SSRI with another can cause delayed, recurrent hyponatremia in elderly patients. Plasma sodium concentrations must be monitored, not only in the first weeks of treatment, but throughout the full course.
Arinzon
Zeev H
ZH
Department of Internal Medicine, Frieda Schiff Warburg Geriatric Medical Center, Ministry of Health, Dora, Netanya, Israel. Darinzon@newmail.net
Lehman
Yehoshua A
YA
Fidelman
Zeev G
ZG
Krasnyansky
Irina I
II
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D016666:Fluvoxamine / Q000009:adverse effects*; D006801:Humans; D007177:Inappropriate ADH Syndrome / Q000139:chemically induced*; D017374:Paroxetine / Q000009:adverse effects*; D012008:Recurrence; D017367:Selective Serotonin Reuptake Inhibitors / Q000009:adverse effects*; D012964:Sodium / Q000097:blood*; D013997:Time Factors
D016666:Fluvoxamine; D017374:Paroxetine; D017367:Selective Serotonin Reuptake Inhibitors; D012964:Sodium