# Low urinary selenium concentration is associated with nonthyroidal illness syndrome in hospitalized patients with COVID-19

## TL;DR

Low urinary selenium levels are linked to nonthyroidal illness syndrome in hospitalized COVID-19 patients.

## Contribution

The study identifies a novel association between low urinary selenium and NTIS in hospitalized COVID-19 patients.

## Key findings

- NTIS was significantly associated with the lowest urinary selenium concentration (USC < 25 µg/L).
- Thyroiditis was the most common thyroid complication but not linked to USC.
- Low USC was observed in 5.7% of patients with NTIS.

## Abstract

This study aimed to assess urinary selenium concentration (USC) and its
correlation with non-thyroidal illness syndrome (NTIS) and inflammatory
markers in hospitalized adult patients with COVID-19.

A prospective study was conducted to investigate urinary selenium (Se)
concentration in adult patients hospitalized with COVID-19 between June and
August 2020. Urine and serum samples were collected before complications
occurred, always within the first 48 hours after onset. A total of 121
patients were stratified into three tertiles based on USC: (i) USC < 25
µg/L (40), (ii) USC
25-39 µg/L (41),
and (iii) USC > 39 µg/L (40). ICP-MS was employed to measure urinary Se
concentration. NTIS was defined by free triiodothyronine below 2.3 pg/L
accompanied by low or normal thyroid-stimulating hormone levels.

NTIS was observed in a low prevalence (5.7%) and was significantly associated
with patients having the lowest USC (n = 6, p = 0.008). Thyroiditis was the
most prevalent thyroid complication (23.9%); however, there was no
significant association with USC (p > 0.05).

The association between low USC and NTIS was evident in this cohort.