# Arginine-vasopressin deficiency due to long COVID-associated infundibulo-neurohypophysitis

## TL;DR

A rare case of arginine-vasopressin deficiency linked to long COVID is reported, suggesting a possible new manifestation of the condition.

## Contribution

This case highlights infundibulo-neurohypophysitis as a potential cause of AVP-D in long COVID patients.

## Key findings

- A 47-year-old man developed AVP-D 8 weeks after mild COVID-19 with no other known causes.
- MRI suggested infundibulo-neurohypophysitis, and desmopressin treatment was effective.
- The case supports AVP-D as a rare long COVID manifestation despite lack of molecular confirmation.

## Abstract

Long COVID is defined by the occurrence of signs, symptoms, and conditions that develop
after COVID-19 and may affect several organs and systems. Arginine-vasopressin deficiency
(AVP-D; central diabetes insipidus) is a very rare complication of COVID-19 and SARS-CoV-2
immunization. Case reports, original studies, and reviews on AVP-D and long COVID
published until February 2024 were retrieved from PubMed. A 47-year-old man presented with
polydipsia, polyuria, memory loss, and mental fog 8 weeks after an episode of mild
COVID-19. His past personal and family medical history were unremarkable. Biochemical
evaluation was relevant for low urine osmolality and a 24-hour urine volume of 10,350 mL.
Basal anterior pituitary evaluation was normal. A water deprivation test was started and
interrupted after 2 hours due to the development of hypernatremia, high serum osmolality,
and low urine osmolality. Urine osmolality significantly increased after intranasal
desmopressin 20 µg. Contrast-enhanced pituitary MRI was suggestive of
infundibulo-neurohypophysitis. Further biochemical, genetic, and imaging tests excluded
secondary AVP-D causes.The patient was subsequently started on oral desmopressin, showing
prompt response. After a follow-up of 20 months, he remained well-controlled with isolated
AVP-D. Although molecular and histologic confirmation of SARS-CoV-2
infundibulo-neurohypophysitis could not be investigated, a strong temporal relationship
and the absence of an alternative diagnosis rendered plausible the inclusion of AVP-D in
the myriad of long COVID manifestations. Further studies with patients recovered from
COVID-19 are necessary for a better understanding of the epidemiology, pathophysiology,
and clinical course of this very rare endocrine condition.