Difficult-to-treat Syndrome of Inappropriate Antidiuretic Hormone Secretion in a Patient with Secondary Central Nervous System Lymphoma.

Abstract

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is defined as hyponatremia with inappropriately concentrated urine in a euvolemic patient. SIADH is associated with a wide spectrum of clinical conditions. In the hospital, hyponatremia carries significant mortality with a prolonged duration of inpatient stay. It is imperative that the underlying cause is appropriately investigated and such patients are closely monitored. This article presents a case of difficult-to-treat hyponatremia secondary to SIADH in a patient with a rare isolated central nervous system (CNS) relapse from a non-Hodgkin's lymphoma (NHL). A relapse, particularly affecting the CNS, carries a poor prognosis. The patient was started on dexamethasone and offered treatment with methotrexate but declined. The hyponatremia failed to respond to fluid restriction and demeclocycline. The hyponatremia responded to a single dose of tolvaptan. Clinicians should have a low index of suspicion for a relapse of lymphoma as a cause of difficult to treat hyponatremia in any patient who has previously had remission from lymphoma treatment.

• Authors: Hareesh Joshi, Shonit Nagumantry, Floyd Pierres, Samson O Oyibo, Satyanarayana V Sagi
• Journal: Cureus (Cureus) Vol. 11 Issue 1 Pg. e3905 (Jan 17 2019) ISSN: 2168-8184 [Print] United States
• PMID: 30931179 (Publication Type: Case Reports)