Immune thrombocytopenia (ITP) as a COVID-19 sequelae could be associated with vitamin B12 deficiency, according to a recent study in Cureus.

“This report throws some light on the reasons behind some of the cases of ITP being either no or slow responders to the conventional treatment regimen in the background of hidden or unveiled cobalamin deficiency,” the authors wrote.

Read more about ITP etiology

This case report describes a 64-year-old male who presented with black stools for the past 2 days. He denied any other symptoms, such as fever, abdominal pain, or vomiting. His past medical history is positive for type 2 diabetes treated with oral antidiabetic agents. He was discharged 1 week prior after a hospitalization course for moderate COVID-19-associated pneumonia.

During his hospital stay, he received remdesivir, vitamin C, methylprednisolone, insulin, low-molecular-weight heparin, and zinc. Upon discharge, he followed a regimen that included daily apixaban 5 mg and prednisolone 40 mg, as well as his usual oral antidiabetics, vitamin C, and zinc.

His physical admission exam reported a conscious, alert, afebrile patient with no evidence of reveal pallor, icterus, ecchymosis, or purpura. Blood work revealed severe thrombocytopenia with a platelet count of 22,000 / cumm. The rest of the parameters, including hemoglobin, reticulocyte count, and white blood cell count, were normal.

The coagulation profile, liver and renal function tests were also within normal limits. Malaria and dengue serologies were negative. A subsequent test identified low vitamin B12 levels as 86 pg/ml. Notably, the patient’s discharge laboratory results from his previous hospitalization reported a platelet count of 1,68.00 / cumm.

Treatment included 1 unit of single donor platelet, methylprednisolone given in a pulsed manner, and pantoprazole. On the third day, his platelet count increased to 58,000 / cumm, and an upper endoscopy reported antral gastritis and esophageal candidiasis. The healthcare team added fluconazole and vitamin B12 at a dose of 1500 mg orally daily. On days 5 and 7, the platelet count decreased again to 29,000 / cumm and 27,000 / cumm, respectively.

A peripheral blood smear showcased a low quantity of large platelets, hypersegmented neutrophils, alliptocytes, and the absence of atypical cells or parasites. Bone marrow biopsy further reported thrombocytopenia and morphologic characteristics suggestive of megaloblastosis.

Physicians then suspected ITP and began treatment with IVIg and eltrombopag. On the second day of treatment, the platelet count reached 42,000 / cumm but decreased to 20,000 /cumm on day 4. He started receiving azathioprine and a combination of B1, B6, and B12 instead of cobalamin. After 2, 4, and 6 days, the platelet count progressively increased to 46,000 / cumm and 68,000 / cumm, and 78,000 / cumm, respectively.

“Although the mechanism behind cytopenia in cobalamin deficiency is defective DNA synthesis, which is a well-known factor, thrombocytopenia in COVID-19 has been postulated to be due to various mechanisms,” the authors noted.


Bijaya M, Ansari Z, Koshy B, Sunder A. Immune thrombocytopenia secondary to COVID-19 in a vitamin B12-deficient patient: a diagnostic dilemma and therapeutic challenge. Cureus. Published online June 9, 2023. doi:10.7759/cureus.40199