SUN-409 Diabetes Insipidus Central: Idiophatic versus Autoinmune?

BACKGROUND Central diabetes insipidus (CDI) is a rare disorder characterized by the excretion of abnormally large volumes of hypotonic urine due to a lack of AVP. The etiology of CDI is unknown in over one third of the cases and is classified as idiopathic. Autoimmunity has been found to be the cause of several endocrine diseases previously classified as idiopathic, but no specific clinical, immunological, and/or radiological pattern has been unequivocally associated with autoimmunity in patients with CDI. CLINICAL CASE A 28 years old woman attended with five-month illness time characterized by polydipsia, associated with polyuria at night and asthenia. Throbbing frontal headache is added 8/10 that decreases with liquid fluids intake. Was evaluated by a doctor, prescribing acetaminophen 500mg conditional to pain. 2 months before admission, an endocrinologist in a clinic, found serum sodium: 158mg/dL, so she was referred. Medical history: 3 previous pregnancies, last delivery 10 months ago, without uterine dynamics, normal breastfeeding. Blood tests: basal glucose: 98mg/dL, FSH: 6.03mU/mL (follicular phase: 3.3-11.3), Estradiol: 67.17pg/mL (follicular phase: 10-178), TSH: 2.08uU / mL (0.27-4.2), T4L: 1.55ng / dL (0.9-1.7), prolactin: 17.02ng / mL (4.79-23.3), insulin: 6.4, urinary sodium: 14.1, urinary chlorine: 13.1, urinary potassium: 7.51. A water deprivation test was performed , with the following baseline values: weight 65kg, serum sodium 142mg/dL, serum osmolarity 288.1mmol / kg, presenting excess thirst. Two hours after starting the test, sensation :weight: 64kg, accumulated urinary volume: 710cc, serum sodium 146mg / dL, serum osmolarity 296.7mmol / kg, urinary osmolarity 158mOsm/kg. The test was stopped, suspended anding the test and 10ug of and intranasal desmopressin was administered, obtaining a a positive results with a post-desmopressin urine osmolarity at of 573mOsm/kg and 2 hours later, 512mOsm/kg, indicating CDI as the diagnosis. The pituitary MRI was reported as “absence of posterior pituitary and absence of T1 signal increase”. No other injuries were seen. Currently, the patient is on treatment with Intranasal Desmopressin 10ug intranasal every 24hrs, with complete improvement of symptoms. CONCLUSIONS The most common causes of CDI are idiopathic and are associated with autoinmmune process. The autoimmune CDI is associated with AVP antibodies (AVPcAb). It is most prevalent in women and the age of onset before 30 years, is an independent factor associated with AVPcAb in 53% of cases. Likewise, the duration of the disease over 5 months, complete CDI and the absence of bright neurohypophyseal spots at MRI, are conditions present in the patient that can tip the diagnosis towards the autoimmune etiology.