SHM Converge Scientific Abstract ePoster Gallery-A Salty Scenario: Trimethoprim-Sulfamethoxazole Induced Syndrome of Inappropriate Antidiuretic Hormone

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This case report describes a 54-year-old woman with uncontrolled type 2 diabetes, hypertension, obesity, and a recent diabetic foot infection who developed severe hyponatremia after starting trimethoprim-sulfamethoxazole (TMP/SMX) and metronidazole as an outpatient. Four days after beginning antibiotics, she returned with fever, nausea, vomiting, and worsening foot pain. Initial labs showed marked hyponatremia (Na 121, later 117), leukocytosis, and elevated glucose. She appeared clinically hypovolemic, so clinicians treated presumed sepsis and volume depletion with large-volume IV fluids and stopped TMP/SMX.<br /><br />Despite aggressive fluid resuscitation, her sodium worsened rather than improved. Over time, her exam and labs shifted toward euvolemia, with low BUN and persistent hyponatremia. Once IV fluids were stopped, she was treated with fluid restriction and salt tablets, after which sodium gradually improved. Repeat urine studies showed inappropriately concentrated urine and urine sodium levels consistent with SIADH.<br /><br />The report emphasizes that TMP/SMX is known not only for creatinine rise and hyperkalemia, but also for causing hyponatremia through either renal salt wasting or SIADH. In hospitalized patients, hyponatremia often has multiple possible causes, and failure of initial treatment should prompt reassessment of volume status and diagnosis. The authors conclude that SIADH should be considered as a potential TMP/SMX adverse effect, and careful medication review is essential when evaluating hyponatremia.

Asset Subtitle

Kevin C. Chang

Meta Tag

Author List David Chung, Kevin C. Chang

Category Clinical Vignettes

Concept Trimethoprim-sulfamethoxazole

Concept Hyponatremia

Concept Syndrome of Inappropriate Antidiuretic Hormone Secretion

Concept Hypovolemic Hyponatremia

Concept Renal Salt Wasting

Distinguished Non-Finalist

Presenter Organization University of Southern California / Los Angeles General Medical Center

Presenting Author Kevin C. Chang

Track Adult

Keywords

hyponatremia

trimethoprim-sulfamethoxazole

TMP/SMX

SIADH

diabetic foot infection

type 2 diabetes

volume depletion

fluid restriction

salt tablets

urine sodium

Trimethoprim-sulfamethoxazole

Hyponatremia

Syndrome of Inappropriate Antidiuretic Hormone Secretion

Hypovolemic Hyponatremia

Renal Salt Wasting