Sucessfull treatment of EBV-associated SIADH with V2 receptor antagonist

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common entity in patient with hyponatriaemia, often associated with tumors, central nervous problems or due to various drugs. Less frequently infectious diseases like herpes simplex viruses are the cause.

Epstein-Barr virus (EBV) is a common viral disease. While during childhood or adolescence the infection is often asymptomatic, more than 50% of affected adults have a severe clinical course. Common symptoms include fever, lymphadenopathy, hepatosplenomegaly and pharyngitis. Similarly, rare complications are more common in adulthood and include hematological alterations, myocarditis but also neurological complications such as encephalitis, neuritis, myelitis, facial nerve palsy or Guillain-Barré syndrome. SIADH has been described following EBV infections especially in tumor patients. Here we present for the first time a case of a previously healthy male patient with infectious mononucleosis and SIADH with symptomatic hyponatriaemia that was successfully treated with an oral V2 receptor antagonist. Treatment with 7.5 mg tolvaptan for three days gradually normalized the serum sodium levels and resulted in clinical improvement.

Unfortunately, the clinical course was complicated by meningoencephalitis, diffuse paroxysmal cerebral dysrhythmia and parainfectious Guillain-Barré syndrome. Therapy with immunoglobulins for five days ameliorated the neurological symptoms. However, the patient required rehabilitation efforts for several weeks and until complete clinical remission was achieved.

The present case shows that therapy with an V2 receptor antagonist may be a therapeutic option in infection-associated SIADH.