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Blood Clots and Long Covid



Just when I decided to have a social media break there has been a flurry of research papers on Long Covid. So I am a little late to the "blood clot" party - sorry - but hopefully I can pull everything together for you.


The newest research paper is written by Prof Resia Pretorius, a researcher in the Department of Physiological Science at Stellenbosch University. She started looking at micro clots and their molecular content in blood samples from individuals with Long COVID. The findings have since been peer-reviewed and published in the journal Cardiovascular Diabetology in August 2021 - "The Persistent clotting protein pathology in Long COVID/Post-Acute Sequelae of COVID-19 (PASC) is accompanied by increased levels of antiplasmin".


In the acute stages of Covid-19 it has been theorised that symptoms where likely due to coagulopathies (a derangement in the body leading to excessive bleeding or clotting). In the case of acute COVID it is probably due to hypercoagulation (excessive clotting) and hyperactivation of platelets (the blood cells that cause clotting to occur). The research team hypothesised:


"Given that blood clots can block microcapillaries and thereby inhibit oxygen exchange, we here investigate if the lingering symptoms that individuals with Long COVID/PASC manifest might be due to the presence of persistent circulating plasma microclots that are resistant to fibrinolysis."


They felt that the many unifying symptoms of Long Covid eg fatigue, breathlessness, chest pain, anxiety could be due to micro clots and inhibited oxygen exchange.


What they did

They looked plasma samples from

  • healthy individuals

  • individuals with Type 2 Diabetes Mellitus (T2DM)

  • those with acute COVID-19

  • those with Long COVID/PASC symptoms.


What they found


  1. The plasma samples from Acute COVID and Long COVID/PASC sufferers still contained large amyloid deposits termed microclots.

  2. These micro clots were resistant to fibrinolysis (breaking down by enzymes) compared to the plasma from the control and diabetic group.

  3. Various inflammatory molecules were increased in the plasma in those with Acute and Long Covid.

  4. There was a substantial increase in antiplasmin ( which would cause less breakdown of clots), fibrinogen chains (which make blood clots) and Serum Amyloid A (trapped in the fibrinolytic-resistant microclots and prevents their breakdown)



Rose Cottage Doc side note

Serum Amyloid A is a protein that is secreted in the acute phase of inflammation. It has been implicated in chronic inflammatory conditions such as amyloidosis, atherosclerosis and rheumatoid arthritis. Signs and symptoms of Amyloidosis may include diarrhoea, weight loss, feeling tired, enlargement of the tongue, bleeding, numbness, feeling faint when standing, swelling of the legs, or enlargement of the spleen.


The following diagram shows how significant the findings were:


Figure: Volcano plots of the protein distribution between pairwise sample comparisons (controls vs COVID-19; controls vs Long COVID/PASC; COVID-19 vs Long COVID/PASC). Oranges dots show proteins above the significance levels as indicated by the dotted line.



What they concluded

Clotting pathologies exist in both acute COVID-19 infection and in Long COVID/PASC. It may be that the plasmin and antiplasmin balance are central to pathologies in Long COVID. These patients might benefit from following a regime of continued anticlotting therapy to support the fibrinolytic system function ie break down of micro clots.


Anti-clotting therapy could be:

  • a DOAC- a direct oral anticoagulant such as dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa), and betrixaban (Bevyxxa)

  • Heparin

  • Warfarin

  • Low dose baby aspirin

Alternative treatments could be high dose Omega 3 supplements, bromelain, lumbrokinase, nattokinase.


What they will do next

Despite this paper being peer reviewed the sample size was small so the team have secured funding to repeat the research though on a much larger scale.


Rose Cottage Doc conclusion

- About 2 months into my Long Covid I really felt I was suffering from a pulmonary embolus (lung clot). I was breathless on exertion, I had chest pain, I had burning lung pains, was tachycardic and my oxygen levels desaturated on cleaning my teeth or squatting or walking on an incline. I had numerous investigations but was told by my respiratory consultant that my scans were clear and so I did not have anything wrong with my lungs. As you may remember I started low dose aspirin anyway. I knew what my body was telling me. After reading this paper I am so glad I did - even though I have no idea if it was beneficial!

Many of you have elevated D-Dimer results which show that there IS inflammation still going on in your bodies but not enough for your doctor to investigate you for a clot in your lung (PE) or leg (DVT) or brain. Microemboli could be the reason.

If you have symptoms of continuing breathlessness, chest pain, desaturations, persistent headaches, no periods, brain fog and chronic fatigue please show your doctor this article to get a full clotting work up and investigations to exclude micro emboli. Many with Long Covid are being diagnosed with emboli six months plus into their Long Covid.

Please make sure you are appropriately investigated first. If you wish to start low dose aspirin discuss it with your doctor first as you may have contraindications to it.


Reference: “Persistent clotting protein pathology in Long COVID/Post-Acute Sequelae of COVID-19 (PASC) is accompanied by increased levels of antiplasmin” by Etheresia Pretorius, Mare Vlok, Chantelle Venter, Johannes A. Bezuidenhout, Gert Jacobus Laubscher, Janami Steenkamp and Douglas B. Kell, 23 August 2021, Cardiovascular Diabetology. DOI: 10.1186/s12933-021-01359-7


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