A prospective study on endocrine function in patients with long-COVID symptoms.

Objective: To investigate hormonal status in patients with long-COVID and explore the interrelationship between hormone levels and long-COVID symptoms.

Design: Prospective observational study.

Participants: Patients who visited our long-COVID outpatients' clinic due to long-COVID symptoms from February 2021 to December 2022.

Measurements: Total triiodothyronine, free thyroxine, thyrotropin, thyroglobulin, anti-thyroperoxidase, and antithyroglobulin autoantibodies were measured for thyroid assessment. Other hormones measured were growth hormone, insulin-like growth factor 1 (IGF-1), adrenocorticotropic hormone (ACTH), serum cortisol, dehydroepiandrosterone sulfate (DHEA-S), total testosterone, plasma insulin, and C-peptide. Blood glucose and glycosylated hemoglobin were also measured. To assess adrenal reserve, an ACTH stimulation test was performed. The fatigue assessment scale (FAS) was used to evaluate fatigue severity.

Results: Eighty-four adult patients were included. Overall, 40.5% of the patients had at least one endocrine disorder. These included prediabetes (21.4%), low DHEA-S (21.4%), subclinical hypothyroidism (3.6%), non-specific thyroid function abnormality (7.1%), thyroid autoimmunity (7.1%), low testosterone in males (6.6%), and low IGF-1 (3.6%). All patients had normal adrenal reserve. Long-COVID-19 symptoms were present in all patients and the most commonly reported symptom was fatigue (89.3%). The FAS score was higher than normal (≥ 22) in 42.8% of patients. There were no associations between patients' symptoms and hormone levels. Diabetic patients reported confusion (p = 0.020) and hair loss (p = 0.040) more often than non-diabetics.

Conclusions: The evaluation of endocrine function 3 months after a positive SARS-CoV2 test revealed only subclinical syndromes. The vast majority of patients reported mainly fatigue, among other symptoms, which were unrelated, however, to endocrine function.