MON-LB070 Lymphocytic Infundibulo-Neurohypophysitis Producing Regressive Postpartum Diabetes Insipidus

Background : Lymphocytic Infundibulo-neuro-hypophysitis (LINH) is a rare autoimmune disease that typically presents as acute onset diabetes insipidus (DI) with intracranial mass-effect symptoms. The diagnosis is based on: clinical features, electrolyte and hormonal dosages, MRI imaging and coexistence of other autoimmune disorders; sometimes autoantibodies to AVP-secreting cells (AVPcAb) are detected (1). Clinical case: We present the rare case of a 25 years old female patient presenting in an outpatient clinic, 4 months postpartum, with polyuria and polydipsia, intense headache and visual disturbances (blurred view and fatigue at reading). A diagnosis of central diabetes insipidus (CID) was established based on: dilute urine, low natriuria, negative fluid deprivation test and positive response to desmopressin. A treatment with desmopressin (Minirin Melt®) 2X120 mcg/day was prescribed, followed by the remission of polyuria and polydipsia but persistence of the headache. No imaging was performed at the time and the patient was lost from follow-up. After 22 months she was admitted in our service for further evaluation complaining of persistent daily headache, and intolerance to the initial doses of desmopressin producing intense and pulsatile headache short time after administration. The initial visual disturbances were now remitted. Analysis confirmed CDI by spontaneous dilute urine, negative fluid deprivation test, but good response to low doses of desmopressin (60 mcg Minirin Melt®). Antidiuretic hormone (ADH) level, at the end of the fluid deprivation test, was in the low values of the normal (2.3 pg/ml, n.r. 2-8 ) pointing to a partial restoration of ADH secretion. MRI imaging showed absence of the bright spot of neuro-hypophysis and slight enlargement of the pituitary stalk with enhanced contrast, characteristic features of lymphocytic infundibulo-neuro-hypophysitis (2). Pituitary biopsy and AVPcAb or Rabphilin (Rab) antibody dosage were not available. Adeno-hypophysis hormones and peripheral hormones were in the normal range, showing adeno-hypophysis integrity. No other autoimmune diseases were detected. Treatment with desmopressin was reinstated with lower doses (Minirin Melt® 2X60 mcg/day) followed by remission of polyuria and polydipsia and good tolerance. Taking into account the evolution of the disease, in the future months we expect a complete remission of the CDI. Conclusion: We present a rare case of postpartum CDI produced by LINH evolving towards spontaneous restoration of the ADH secretion. References: (1) Juan-Andres Rivera Lymphocytic hypophysitis: Disease spectrum and approach to diagnosis and therapy. Pituitary 2006 ;9:35–45. (2) Hitoshi Sugihara Review on Recent Topics in Hypophysitis. J Nippon Med. Sch. 2017; 84 (5) Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.