A Case of Arginine Vasopressin Deficiency with Anti-rabphilin-3A Antibody Positivity Following an Influenza Infection

Lymphocytic infundibulo-neurohypophysitis (LINH) presents with arginine vasopressin deficiency (AVP-D), also known as central diabetes insipidus, caused by autoimmune mechanisms in the infundibulum and posterior pituitary. A 32-year-old man developed polydipsia and polyuria two months after influenza infection. A hypertonic saline test revealed no AVP responses. Magnetic resonance imaging demonstrated the loss of posterior pituitary hyperintensity. The patient tested positive for serum anti-rabphilin-3A antibodies, a diagnostic marker for LINH. This is the first report of a case of probable LINH with anti-rabphilin-3A antibody positivity following an influenza infection, thus providing novel clinical insight into the diagnostic evaluation of post-infectious AVP-D.