[Connection between hyponatriemia and local herpes in an old lady?]

SIADH with Severe Hyponatremia in an Elderly Man with Herpes Zoster Infection: A Causal or Casual Association?

Syndrome of inappropriate antidiuretic hormone (SIADH) secretion is the most common cause of hypotonic 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 A one month after discharge, tolvaptan was withdrawn, due to inadequate prescription criteria, after which hyponatremia relapsed several times and was properly treated; eventually fever and sopor occurred and the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.

Syndrome of inappropriate secretion of antidiuretic hormone associated with localized herpes zoster ophthalmicus

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with localized herpes zoster is rarely reported and may be under-appreciated. We describe two diabetic men with herpes zoster ophthalmicus (HZO) who developed hyponatremia (114 and 116 mmol/L) during acute illness. Both were euvolemic and had elevated urine osmolality (435 and 368 mmol/kg.H(2)O) and sodium (Na(+)) concentration (61 and 63 mmol/L) along with normal cardiac, renal, liver, and endocrine function consistent with the diagnosis of SIADH. Thorough investigation for other causes of SIADH, including detailed physical examination, laboratory studies, and computed tomography of the brain, chest, and abdomen, were negative. Despite antiviral therapy (acyclovir) for herpes zoster, ophthalmoplegia, keratitis, and post-herpetic neuralgia (PHN) developed. Even with fluid restriction and high salt diet, SIADH lasted for 3 to 4 months and resolved concomitantly with resolution of PHN, suggesting an association between SIADH and HZO. These two cases raise the potential for herpes zoster infection, especially HZO, to involve the regulatory pathway of ADH secretion, contributing to SIADH. The presence of PHN, which reflects greater neural damage may, at least in part, explain the prolonged ADH secretion and hyponatremia.