Central Diabetes Insipidus in a Patient with Stiff Person Syndrome

Background: Central diabetes insipidus (CDI) is a rare hypothalamic-pituitary disease due to the deficiency of arginine vasopressin (AVP) synthesis of which more than one third of etiologies are unidentified. Autoimmunity is associated with one third of patients with apparently idiopathic CDI. The most common antibody detected in auto immune CDI is autoantibodies to AVP-secreting cells (AVPcAb). Stiff-person syndrome (SPS) is a rare neurological disorder with features of an autoimmune disease. It is characterized by fluctuating muscle rigidity in the trunk and limbs and a heightened sensitivity to stimuli. It is well known that SPS is associated with multiple auto immune endocrinopathy including auto immune diabetes and auto immune thyroid disease. The association between SPS and CDI is not well documented in the literature. Case information: We report a case of 51 year old female who developed CDI while being treated for SPS unmasked by high dose steroids. Result: Anti amphiphysin is the only antibody detected in our patient. Animal studies showed a high expression of amphiphysin in anterior and posterior pituitary gland, data in human are still vague .One theory is that anti-amphiphysin antibodies attack the amphiphysin molecules in the AVP secreting cells and inhibit release of AVP. Conclusion: This antibody could hint towards the autoimmune cause of CDI.