Researchers from Qatar reported the rare case of a patient who developed concomitant autoimmune hemolytic anemia and pulmonary embolism 2 weeks after being diagnosed with mild COVID-19.

“Despite its rarity, [autoimmune hemolytic anemia] can be associated with COVID-19,” they wrote and added that the condition should be suspected in patients with recent COVID-19 infection who develop unexplained anemia.

There are 4 types of autoimmune hemolytic anemia, 1 of which is cold agglutinin disease, where the immune system mistakenly attacks the body’s own erythrocytes under cold conditions. Even though the exact cause of cold agglutinin disease is not known, research has shown that in some cases, it can develop secondary to some bacterial and viral infections. 

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Autoimmune hemolytic anemia associated with COVID-19 has increasingly been reported in the literature.

Given that the disease might occur after a patient has been discharged from the hospital or quarantine facility, the authors suggested that a complete blood count should be performed within 2 to 4 weeks of COVID-19 in case of unexplained anemia.

Because the patient they reported on also developed pulmonary embolism, the researchers recommend having a lower threshold for a diagnosis of pulmonary embolism in patients with autoimmune hemolytic anemia, especially if significant shortness of breath or persistent tachycardia is present.

Read more about cold agglutinin disease etiology

A few cases of autoimmune hemolytic anemia have been reported in the literature associated with severe COVID-19. This is, however, the first report of simultaneous autoimmune hemolytic anemia and pulmonary embolism following mild COVID-19.

The patient was treated with rivaroxaban for his pulmonary embolism and with a tapering dose of prednisolone for his autoimmune hemolytic anemia and was discharged from the hospital. It is not known what happened to him later as he was lost to follow-up.


Al-Mashdali AF, Ata YM, Yassin MA. Concomitant autoimmune hemolytic anemia and pulmonary embolism associated with mild COVID-19: a case report. Clin Case Rep. 2021;18;9(10):e04952. doi:10.1002/ccr3.4952