Urinary retention: a cause of hyponatremia?
BACKGROUND
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of hyponatremia in elderly hospitalized patients; however in many patients the etiology remains unclear even after routine investigations.


OBJECTIVE
To report our experience of the association of hyponatremia and urinary retention in elderly hospitalized patients.


METHODS
Six patients with hyponatremia and urinary retention who were admitted to the geriatric department in our hospital during a four-year period (2001-2004).


RESULTS
The mean age of the patients was 85 years. The mean serum sodium level was 120 mEq/l, average volume of retained urine was 933 ml (range 500-1,500 ml). All patients underwent a comprehensive work-up seeking a possible cause for the hyponatremia. The diagnostic work-up was negative. In 5 of the patients the laboratory findings fulfilled the criteria for SIADH. In all patients hyponatremia resolved following urinary catheterization and fluid restriction. All patients made a complete recovery.


CONCLUSIONS
Potentially, urinary retention by itself may cause hyponatremia. The possible mechanism for this is SIADH, triggered by bladder distention or pain due to bladder distention. Urinary catheterization may be the key to treatment in these cases of hyponatremia.
Galperin
Ilia
I
Geriatric Department, Shaare Zedek Medical Center, Jerusalem, Israel. son@szmc.org.il
Friedmann
Reuven
R
Feldman
Helena
H
Sonnenblick
Moshe
M
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000209:etiology* / Q000378:metabolism; D007177:Inappropriate ADH Syndrome / Q000150:complications* / Q000378:metabolism; D008297:Male; D012964:Sodium / Q000097:blood / Q000652:urine; D014546:Urinary Catheterization; D016055:Urinary Retention / Q000150:complications* / Q000175:diagnosis
D012964:Sodium