# Nephrogenic diabetes insipidus in a geriatric patient affected by SARS-CoV-2: complexity of a diagnosis, complexity of a virus

## TL;DR

An elderly patient with SARS-CoV-2 developed nephrogenic diabetes insipidus, highlighting the virus's potential to affect kidney function in unexpected ways.

## Contribution

This case suggests SARS-CoV-2 may target distal nephron segments, including the collecting duct, through direct or indirect mechanisms.

## Key findings

- A geriatric patient with SARS-CoV-2 developed nephrogenic diabetes insipidus after 20 days of hospitalization.
- The diagnosis was supported by clinical and laboratory evidence despite prior lithium therapy.
- The collecting duct may be a target for SARS-CoV-2, possibly due to upstream nephron damage.

## Abstract

Coronavirus disease 2019 (COVID-19) has an important impact on the kidney through direct and indirect damage mechanisms. Most previous studies have highlighted lesions caused by this virus in the early segments of the nephron. However, due to the antigenic characteristics of the virus, with almost ubiquitous receptors, and the molecular release it triggers, the distal segments of the nephron could also be affected.

A 71 year-old-man with respiratory failure while suffering from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia presented with typical symptoms of diabetes insipidus after ~20 days of hospitalization. The water deprivation test led to the diagnosis of nephrogenic diabetes insipidus. The aetiological study was complex, in particular because of the patient’s previous lithium therapy.

The sequence of pathognomonic events typical of diabetes insipidus associated with anamnestic, clinical and laboratory evidence strongly supported the diagnosis of nephrogenic diabetes insipidus due to SARS-CoV-2 rather than other aetiologies.

The collecting duct could represent a target for SARS-CoV-2 infection, directly or indirectly, as a result of lesions of upstream portions of the nephron, which would cascade into the distal segment. Other molecules, besides angiotensin 2 converting enzyme, might be involved in facilitating the viral aggression. The complexity of the geriatric patient shows the importance of a comprehensive approach that integrates careful monitoring of clinical signs and symptoms and laboratory and instrumental tests. This is especially important in the context of SARS-CoV-2 infection and in the management of its unexpected complications.