Endocrine Abstracts

Introduction: The endocrine complications of COVID-19 remain largely unknown. Cases of central diabetes insipidus (CDI) have been reported after COVID-19, with hypophysitis being the most likely cause. COVID-19 vaccines potential adverse effects may mimetize some of these complications. We present a case of a woman who developed CDI one week after the 2 nd dose of BNT162b2 mRNA COVID-19 vaccine.

Case Report: Female patient, 37 years old, with rheumatoid arthritis under a well tolerated therapy with adalimumab (40 mg twice a month) since December 2018. In October 2021, she reported intense thirst and polyuria starting 4 months earlier (7 days after second dose of BNT162b2 mRNA COVID-19 vaccine). She denied polyphagia, weight loss, foamy urine, macroscopic hematuria, peripheral or periorbital edema. Blood analysis: creatinine 0.7 mg/dl, glucose 95 mg/dl, Na+ 141 mEq/l, K+ 3.9 mEq/l, TSH 3.8 mcUI/l (0.38-5.33), FT4 0.9 ng/dl (0.6-1.1), cortisol 215.4 nmol/l (185-624), ACTH 21.9 pg/ml (6-48), osmolality 298.2 mOs/lg (250-325); Urine analysis: volume 10 200 mL/24h, osmolality 75 mOs/kg (300-900), density 1.002. She was admitted to the ward to perform a water restriction test: 0’ − Serum osmolality 308.8 mOsm/kg vs. urine osmolality 61.0 mOsm/Kg; 60’ - urine osmolality 102 mOsm/Kg; urine osmolality 1 h after desmopressine was 511 mOsm/kg. MRI of the pituitary gland revealed no abnormal signs consistent with hypophysitis except for the loss of the posterior pituitary bright spot on T1 weighted imaging. Diagnosis of CDI was assumed, and started therapy with desmopressine. Although pituitary biopsy was not conducted, other probable causes of CDI were ruled out. A report of potential adverse effect from BNT162b2 mRNA COVID-19 vaccine was addressed to national health authorities. On the last appointment (December 2021), she was under desmopressin 0.06 mg tid, had no polydipsia or polyuria, BP 110/80 mmHg, and analytical results showed: Serum osmolality 297.2 mOsm/kg, Urine osmolality 148.0 mOsm/kg, FSH 4.76 UI/l, LH 5.62 UI/l, estradiol 323 pmol/l, IGF1 74.8 ng/ml (88-209), PRL 24.7 mg/l (3.3-26.7). Desmopressin was titrated to 0.12 mg bid.

Conclusion: In hypophysitis MRI often shows loss of posterior pituitary bright spot on T1 weighted imaging, pituitary enlargement or stalk thickening but those findings were not present in this patient. However, the same lack of abnormal signs consistent with hypophysitis in MRI has also been reported in 2 cases of CDI following COVID-19 infection. To the best of our knowledge, CDI has never been reported following administration of a COVID-19 vaccine.