Clinical observation: hyponatremia associated with diuretic use and urinary retention in an older man

Hyponatraemia caused by transient syndrome of inappropriate antidiuresis to urinary retention

Hyponatraemia is frequently seen in the emergency department, possibly caused by the syndrome of inappropriate antidiuresis (SIAD). We report three cases in which we believe urinary retention with bladder distention caused hyponatraemia. Laboratory findings fulfilled the criteria for SIAD, for which no cause was found. Possibly pain or sympathetic nerve system activation leads to SIAD. Brisk diuresis occurred after placement of an indwelling urinary catheter with overly correction of sodium for which treatment was necessary. Clinicians should be aware that placement of an indwelling urinary catheter may prompt brisk water diuresis and a tendency to overcorrection.

Prospective determination of the incidence and severity of hyponatraemia in older hospitalised patients with acute urinary tract obstruction

INTRODUCTION

acute urinary tract obstruction (aUTO) is a common finding in older hospitalised patients. Anecdotal reports described hyponatraemia in patients with aUTO, which subsides rapidly with relief of the obstruction.The aim of this study was to determine the incidence, severity and subsequent correction of hyponatraemia in patients with aUTO.

METHODS

this is a prospective, single-centre, observational study including inpatients in the internal medicine and geriatric wards. A total of 204 patients were investigated, 104 with aUTO and 100 controls. The prevalence, severity and associations of hyponatraemia between aUTO and control patients were compared.

RESULTS

the incidence of hyponatraemia was similar in aUTO and control groups 28% versus 22%, respectively (P = 0.42). However, the incidence of severe hyponatraemia was significantly higher in the study group 7% versus 1% (P = 0.04). Mean sodium level was lower in hyponatremic patients with aUTO 127.7 ± 5.9 mEq/l versus 130.8 ± 3 mEq/l (P = 0.013). Serum sodium remained largely unchanged in the control group (∆Na 1.5 ± 2.3 mEq/l) but increased significantly within 48 hours following catheter insertion in patients with urinary retention (∆Na 5.3 ± 4.2 mEq/l overall in the aUTO group and 9.6 ± 3 mEq/l in those with urinary retention and severe hyponatraemia (P = 0.002)).

A rare report of obstructive nephropathy induced hyponatremia

Hyponatremia is a common finding in patients admitted to hospitals in the USA. There is a plethora of causes ranging from excessive diuretic use to volume overload from underlying heart failure or liver cirrhosis. The consequences of missing or mistreating the aforementioned diagnosis can lead to catastrophic outcomes. Here, we focus on a rare yet overlooked cause of hyponatremia: obstructive nephropathy. The causes of obstructive nephropathy in elderly patients are broad with neurogenic bladder being one of the common ones. Our patient is an elderly male who presented with hyponatremia in setting of urine retention post an orthopedic surgery.

Urinary retention as a cause of hyponatremia in an elderly man

Hyponatremia is a common disorder in elderly and can result in changes in cognition, seizures, coma or even respiratory arrest if not recognised and treated. Syndrome of inappropriate anti diuretic hormone secretion (SIADH) is the most common cause of hyponatremia in elderly hospitalised patients and in most cases the etiology cannot be determined on routine investigations. We present a 76 year old male with symptomatic hyponatremia who had chronic urinary retention due to a urethral stricture. His sodium levels improved with catheterisation and worsened again after the catheter was removed. This supports the hypothesis that urinary retention and bladder distension can stimulate ADH release from the posterior pituitary, producing a picture similar to SIADH.