Endocrine Abstracts

JOINT3626

Introduction: Hypophysitis is a rare condition in pediatrics, considered an autoimmune phenomenon, with the most common form being lymphocytic hypophysitis. It frequently presents as central diabetes insipidus (CDI) or growth hormone deficiency (GHD). The diagnosis is clinical and radiological, though in some cases, a biopsy may be required to exclude other systemic or neoplastic diseases. The treatment includes the use of immunosuppressive therapy, with corticosteroids being the first-line therapy.

Case Description: A 15-year-old male patient was admitted for acute liver failure (abdominal pain, vomiting, and jaundice, associated with hyperbilirubinemia, hypertransaminasemia, hypoalbuminemia, and coagulopathy). Endocrinology was consulted due to the finding of hypernatremia. Upon directed questioning, he reported polydipsia, polyuria, and enuresis for 3 weeks. He denied headache or visual disturbances. On physical examination, his weight and height were in the 75-90th and 25th percentiles, respectively, with normal growth velocity, euthyroid status, Tanner stage G4 P4, and testes 15/15 cc. Given the suspicion of CDI, a water deprivation test was performed, confirming the diagnosis with a good response to oral desmopressin. Further studies were conducted, including hypothalamic-pituitary axis evaluation, with sufficient cortisol levels, low thyroid hormone levels consistent with euthyroid sick syndrome, growth hormone resistance (GH 11.1 ng/ml with undetectable IGF1 levels), and arrested puberty (LH 1.4 mUI/ml, FSH 2.16 mUI/ml, and Testosterone 1.12 ng/ml). Alpha-fetoprotein and β-hCG were negative, and skeletal radiographs were normal. A magnetic resonance imaging (MRI) scan revealed the absence of the spontaneously hyperintense signal in T1 of the neurohypophysis. No alterations were observed in the adenohypophysis or the pituitary stalk. During hospitalization, autoimmune hepatitis was confirmed with hypergammaglobulinemia, positive antinuclear antibody (ANA), and anti-smooth muscle antibody (ASMA), prompting the hepatology team to initiate methylprednisone 0.6 mg/kg/day orally. After 72 hours, desmopressin requirements decreased, and was finally discontinued after 10 days due to the development of hyponatremia. Normal sodium levels were maintained after 8 months of follow-up. Thyrotropin, somatotropin, and gonadotropin and testosterone levels normalized, considering previous alterations a transient phenomenon due to systemic disease.

Conclusions: We describe an adolescent who presented with CDI in the context of liver failure, later diagnosed with autoimmune hepatitis. The MRI only revealed the absence of the bright spot, without involvement of the pituitary stalk. Although this finding is present in 20% of the normal population, the clinical presentation, the association with autoimmune disease, and the excellent response to corticosteroid treatment increase the suspicion of a clinical picture compatible with neurohypophysitis.