Electrolyte Blood Press.  2017 Dec;15(2):42-46. 10.5049/EBP.2017.15.2.42.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) Associated with Mediastinal Schwannoma

Affiliations
  • 1Department of Internal Medicine, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Korea. sinani28@hanmail.net, kjr@hallym.or.kr
  • 2Department of Pathology, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Korea.

Abstract

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of euvolemic hypo-osmotic hyponatremia. There are several etiologies of SIADH including neuroendocrine tumor, pulmonary disease, infection, trauma, and medications. Here, we report a case of SIADH associated with a schwannoma involving the mediastinum in a 75-year-old woman who presented with nausea, vomiting, and general weakness. Laboratory testing showed hypo-osmolar hyponatremia, with a serum sodium level of 102mmol/L, serum osmolality of 221mOsm/kg, urine osmolality of 382mOsm/kg, urine sodium of 55 mmol/L, and plasma antidiuretic hormone (ADH) of 4.40 pg/mL. Chest computed tomography identified a 1.5-cm-sized solid enhancing nodule in the right lower paratracheal area. A biopsy specimen was obtained by video-assisted thoracoscopic surgery, which was diagnosed on pathology as a schwannoma. The hyponatremia was completely resolved after schwannoma resection and plasma ADH level decreased from 4.40 pg/mL to 0.86 pg/mL. This case highlights the importance of suspecting and identifying the underlying cause of SIADH when faced with refractory or recurrent hyponatremia, and that on possibility is mediastinal schwannoma

Keyword

Hyponatremia; Syndrome of Inappropriate ADH (SIADH) Secretion; Mediastinal schwannoma

MeSH Terms

Aged
Biopsy
Female
Humans
Hyponatremia
Inappropriate ADH Syndrome
Lung Diseases
Mediastinum
Nausea
Neurilemmoma*
Neuroendocrine Tumors
Osmolar Concentration
Pathology
Plasma
Sodium
Thoracic Surgery, Video-Assisted
Thorax
Vomiting
Sodium
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