Unexplained Bruising on Lower Legs After AZ Vaccine: What to Know

After receiving the AZ vaccine, there is unexplained bruising on the calf?

Hello doctor, I have Sjögren's syndrome and iron deficiency anemia.
After receiving my first dose of the AZ vaccine on July 29 (Thursday), I noticed seven unexplained bruises on my tibia and knee on July 31 (Saturday), each about 1 to 1.5 cm in size.
They are not widespread, painless, and not itchy, and they do not appear to be caused by trauma, as pressing on the bruises does not cause pain.
By August 3 (Tuesday), new bruises had appeared, but the old ones quickly changed from red to deep blue.
I have not experienced any other unusual symptoms, except for slight headaches and dizziness when jogging.
On August 4 (Wednesday), I went to the health center where I received the vaccine to have blood drawn, and the results were as follows: eosinophils 1.1, basophils 2.6, hematocrit 39.6, hemoglobin 12.6 (I have been taking iron supplements, with a previous low of 10), lymphocytes 17.9 (possibly low?), mean corpuscular hemoglobin 29.9, mean corpuscular hemoglobin concentration 31.8, mean corpuscular volume 93.8, monocytes 4.7, neutrophils 73.7 (possibly high?), platelets 261, red blood cells 4.22, RDW-CV 14.4, white blood cells 6.4.
Should I see a hematologist for further evaluation?

capopo, 40~49 year old female. Ask Date: 2021/08/06

Dr. Zeng Guosen reply Internal Medicine

Hello, the blood test did not show any abnormalities in your platelets.
Blood abnormalities related to the AZ vaccine typically occur 10 days to two weeks after vaccination.
Currently, your situation cannot be explained, and it is recommended that you consult a hematologist for further evaluation.
Thank you for your question.

Reply Date: 2021/08/06

More Info

Unexplained bruising after receiving the AstraZeneca (AZ) vaccine can be concerning, especially for individuals with pre-existing conditions such as dry syndrome and iron deficiency anemia. It is important to understand the potential causes of these symptoms and when to seek further medical evaluation.

Firstly, it is not uncommon for individuals to experience some degree of bruising after vaccination. The AZ vaccine, like other vaccines, can cause mild to moderate side effects, including localized reactions at the injection site, fatigue, headache, and occasionally, bruising. However, the appearance of unexplained bruises, especially multiple bruises in areas such as the lower legs, warrants careful consideration.

In your case, the bruises you described on your shins and knees, which appeared a few days after the vaccination, could be attributed to several factors:
1. Vaccine Reaction: While the AZ vaccine is generally well-tolerated, it can lead to immune-mediated reactions that may affect blood clotting mechanisms. This can result in bruising, particularly in individuals who may already have a predisposition due to underlying conditions.

2. Underlying Conditions: Your history of dry syndrome and iron deficiency anemia may contribute to a higher susceptibility to bruising. Dry syndrome can affect the mucous membranes and skin, potentially leading to increased fragility of blood vessels. Iron deficiency anemia can also impact the overall health of your blood cells, making you more prone to bruising.

3. Platelet Function: The blood test results you provided indicate that your platelet count is within the normal range (261), which is reassuring. However, it is important to consider that platelet function can also be affected by various factors, including medications, nutritional deficiencies, and underlying health conditions.
4. Other Causes: Unexplained bruising can also be a sign of other underlying conditions, such as clotting disorders or vascular issues. If the bruising continues to occur or if you experience additional symptoms such as excessive bleeding, fatigue, or changes in your overall health, it would be prudent to seek further evaluation.

Given your symptoms and the appearance of new bruises, it is advisable to consult with a healthcare professional, particularly a hematologist or a specialist in blood disorders. They can perform a thorough evaluation, including additional blood tests to assess your clotting factors and platelet function, and determine if there is an underlying condition that needs to be addressed.

In summary, while some bruising after vaccination can be normal, the presence of multiple unexplained bruises, especially in the context of your existing health conditions, should not be overlooked. It is important to communicate your concerns with your healthcare provider, who can guide you on the appropriate next steps and ensure that any potential issues are addressed promptly.

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