Sick euthyroid syndrome on presentation of COVID-19 patients, a potential marker for disease severity

Yair, Schwarz; Ruth, Percik; Bernice, Oberman; Yaffe, Dana; Eyal, Zimlichman; Amir, Tirosh

OBJECTIVE: Precise risk stratification and triage of COVID-19 patients has become essential in the setting of an overwhelming pandemic burden. Clinical observation has shown a somewhat high prevalence of sick euthyroid syndrome among COVID-19 patients. The study objective was to evaluate the predictive value of free Triiodothyronine (FT3), at the clinical presentation of COVID-19 for disease severity and death. METHODS: This was a retrospective cohort study based on electronic medical records. The study was conducted at Sheba Medical Centre, a tertiary hospital in which several acute and chronic wards have been dedicated to the treatment of COVID-19 patients. The primary outcome measure was death during hospitalization; secondary outcomes included hospitalization in intensive care, mechanical ventilation and length of hospitalization. RESULTS: Of a total of 577 PCR positive COVID-19 patients hospitalized between 02.27.2020 and 07.30.2020, 90 had at least one measurement of TSH, FT4 and FT3 within 3 days of presentation. After excluding patients with pre-existing thyroid disease, exposure to possible interfering drugs prior to FT3 measurement, and patients admitted for rehabilitation, 54 patients were included in the study. Patients in the lowest tertile of FT3, had significantly higher rates of mortality (40%, 5.9%, 5.9% P=0.008), mechanical ventilation (45%, 29.4%, 0%; P=0.007) and ICU admission (55%, 29.4%, 5.9%, P=0.006). In multivariate analyses adjusted for age, Charlson index, creatinine, albumin and WBC count, FT3 remained a significant independent predictor for death. CONCLUSION: FT3 levels early in the presentation of COVID-19 can serve as a prognostic tool for disease severity.