Siadh with severe hyponatremia in an elderly man with herpes zoster infection: A causal or casual association?

Abstract

Syndrome of inappropriate antidiuretic hormone (SIADH) secretion is the most common cause of hypo-tonic hyponatremia in hospitalized patients. An elderly man with severe symptomatic hyponatremia (109 mEq/L) was diagnosed with SIADH that was likely secondary to large cutaneous herpes zoster (HZ) infection. Hypertonic saline and tolvaptan improved the patient’s sodium levels and clinical condition. A one month after discharge, tolvaptan was withdrawn, due to inadequate prescription criteria, after which hyponatremia relapsed several times and was properly treated; eventually fever and sopor occurred and the patient died. SIADH secondary to HZ may induce life-threatening and long-lasting hyponatremia, which requires a prompt diagnosis and treatment.