Hemoglobin Levels in COVID-19 Patients: A Literature Review Sarah Triwinar Sellynastiti a , Musofa Rusli b* , Yetti Hernaningsih c * Corresponding author (musofa-r@fk.unair.ac.id) a Faculty of Medicine, Airlangga University, Surabaya 60132, Indonesia b Department of Internal Medicine, Faculty of Medicine, Airlangga University, Surabaya 60132, Indonesia c Department of Clinical Pathology, Faculty of Medicine, Airlangga University, Surabaya 60132, Indonesia Abstract The COVID-19 pandemic is a global health problem that changed the course of the world. The pandemic began in the city of Wuhan, China in December 2019 and was finally declared a pandemic in March 2020 by the World Health Organization. This disease affects the respiratory system, causing various clinical signs and symptoms. The main pathophysiology of COVID-19 is inflammation, and it can affect a number of bodily systems and functions. One of the impacts of COVID-19 inflammation is the change of hemoglobin levels. This change in hemoglobin levels is an important issue that requires attention, because the level of an individual’s hemoglobin represents their capability to carry and distribute blood. After reviewing previous research articles, it was found that COVID-19 patients have a tendency for hemoglobin decrease. Keywords: COVID-19, hemoglobin, anemia 1. Introduction The Coronavirus Disease 2019 (COVID-19) pandemic has been one of the biggest global health problems in the 21 st century. The pandemic caused many changes in people’s lives mainly because of the mobility restrictions. COVID-19 started in the city of Wuhan in Hubei Province, China in December 2019. The disease was originally spread through a zoonotic manner in Chinese seafood markets, but eventually the infection expanded mainly among human interactions and activities through respiratory droplets. In March of 2020, the World Health Organization (WHO) finally declared COVID-19 as a pandemic across the globe. [1] COVID-19 is caused by a virus called Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) which infects human respiratory system. This virus is a member of the Coronaviridae family. It is widely known that this virus is still related with another viruses, namely SARS-CoV from 2003 and MERS-CoV from 2012 [2]. Specifically, SARS-CoV-2 infects the ciliated bronchial epithelial cells and type-II pneumocytes by attaching itself to the angiotensin-converting enzyme 2 (ACE-2) receptors [3]. Once infected by this virus, patients can develop a variety of symptoms and illnesses, although some cases show no symptoms at all. Coughing, respiratory distress, and fever are some of the more common symptoms of SARS CoV-2 infection, while others may experience other symptoms such as fatigue, myalgia, a number of gastrointestinal disturbances, and other less specific manifestations. [4] The disease’s pathological development in the human body is mainly through the pathway of inflammation. Some inflammatory mediators that has been reported to be involved in the pathophysiology of COVID-19 are interleukins 1, 2, 4, 7, 10, 12, 13, and 17, granulocyte colony-stimulating factor (GCSF), macrophage colony- stimulating factor (MCSF), hepatocyte growth factor (HGF), interferon-gamma (IFN-Ȗ), and tumor necrosis 71 www.ijrp.org IJRP 2022, 114(1), 71-74; doi:.10.47119/IJRP10011411220224183