Introduction
In December 2019, a sudden outbreak of pneumonia caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) occurred in Wuhan, China. Later called Coronavirus Disease 2019 (COVID-19), the disease spread rapidly worldwide and became a pandemic (1). Common clinical manifestations of COVID-19 are fever, cough, shortness of breath, fatigue, headache, hemoptysis, loss of taste or smell, and gastrointestinal manifestations such as nausea, vomiting, anorexia, diarrhea, and abdominal pain (2). The virus detects angiotensin-converting enzyme 2 (ACE-2) as its receptor and binds to it. ACE-2 exists in almost all human tissues including endothelial cells of arteries, small and large veins, heart, alveolar epithelial cells type 1 and 2 in lungs, nasal mucosa, mouth, nasopharynx, kidney, testis, and brain (3). Many reports suggest that the introduction of SARS-CoV2 is associated with decreased ACE-2 activity and that ACE-2 acts as a negative regulator of the renin-angiotensin-aldosterone (RAAS) system in critical situations. RAAS is thus boosted in COVID-19 patients and causes oxidative stress damage to the vascular endothelium (4). In general, endothelial damage is associated with the pathophysiology of COVID-19. Activation of von Willebrand factor (VWF), complement overactivation, excessive neutrophil extracellular traps (NETs) formation, and mitogen-activated protein kinases may also play a role in COVID-19-related coagulation. dysregulated innate immune response and subsequent cytokine storms would also lead to the activation of various “immunothrombotic” pathways and blood coagulation. COVID-19-related coagulation affects different organs including pulmonary arteries, lower limbs, spleen, heart, brain, and kidneys (3). Renal vein thrombosis (RVT) is a condition in which thrombosis occurs in the renal veins or their branches. Acute RVT is often due to trauma, severe dehydration, hypercoagulability, or nephrotic syndrome. RVT is rare and occurs most often in adults with nephrotic syndrome and newborns with low body fluid volume or inherited thrombophilia. While it may present with symptoms such as flank pain, hematuria, or acute kidney injury (AKI), it may also remain asymptomatic until it leads to pulmonary embolism (PE) or accidentally diagnosed by imaging studies (5).