**1. Introduction**

Coronavirus disease (COVID-19) pandemic is caused by the severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) [1, 2]. It represents a global health burden and associated with increased morbidity and mortality. COVID-19 has a diverse and variable spectrum of clinical presentations. The clinical presentations range from mild disease with just upper respiratory tract symptoms to a severe form of the disease including pneumonia and may be multiple organ failure [3].

It became evident that COVID-19 can also affect the extrapulmonary organs, this includes vascular, cardiac, renal and neurological systems [4–7]. Over time, it became more evident that COVID-19 can affect multiple endocrine organs and hormonal substances, leading to negative patients' outcomes. The COVID-19 endocrine manifestations can be found more frequently in those patients with pituitary diseases, diabetes mellitus, obesity and vitamin D deficiency [8].

#### **Figure 1.** *Endocrine COVID-19 manifestations [11].*

Angiotensin-converting enzyme 2 (ACE2) receptors have been identified as a target for the entry SARS-CoV-2 into the cells. The systemic involvement in COVID-19 is due to the almost abundant expression of the angiotensin-converting enzyme 2 (ACE2) receptors, with resulting damage at many organ and tissue levels besides the lung [9, 10]. From the endocrine glands respective, these receptors have been found in the hypothalamus, thyroid, pancreatic, gonads, pituitary gland cells on biopsies from those patients who died from COVID-19, explaining the endocrine involvement after contracting the infection, **Figure 1** [11].

From the initial period of the pandemic, multiple factors have been linked to a higher risk for mortality from COVID-19, including male gender, old age, obesity, DM, hypertension (HTN), cancer, chronic obstructive pulmonary disease, immunocompromised patients and patients with cardiovascular diseases [12].
