Vaccinations have rarely been associated with the development of autoimmune neurological disorders, including narcolepsy1, Gullain-Barré syndrome2 and multiple sclerosis.3 Central diabetes insipidus associated with haemophagocytic lymphohistiocytosis following influenza vaccination has also been reported4, as has a case following probable influenza A infection5.
We describe a previously well 26 year old woman who developed sudden onset polyuria and polydipsia one week following her second annual influenza vaccination. She was alert and systemically well with no focal neurological deficits. Water deprivation test was consistent with central diabetes insipidus. Anterior pituitary hormone testing was within normal limits. MRI scan of her pituitary gland revealed borderline increased thickness of the superior pituitary infundibulum (3mm), which was stable on follow-up imaging. There was no family history of diabetes insipidus. No underlying cause has been identified.
The close temporal relationship between the influenza vaccination and symptom onset raises the suspicion that the vaccination may have triggered diabetes insipidus. Proposed immunological mechanisms underlying inflammatory diseases of the central nervous system following vaccination include molecular mimicry and bystander activation.6
We believe this is the first case report of diabetes insipidus following influenza vaccination not associated with a systemic illness. This case also highlights the difficulty in delineating association from causation when illnesses arise following vaccination.