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The importance of D-Dimer as a marker for Cardiovascular health

D-Dimer has been put on the map in the last year for its sensitivity in indicating microscopic blood clotting - seen in both COVID-19 and the COVID-19 vaccine. Find out more about this effective marker and why it is essential to check this as part of your blood panel screening if you do suspect cardiovascular impairment.

What is D-Dimer?

D-Dimer is a product of fibrin blood clot degradation called fibrinolysis. It is present in minimal amounts in healthy human plasma (100-200 ng/mL). Once the coagulation cascade has been activated D-Dimer raises.

 

D-Dimer is reliably used to detect clotting, typically in deep vein thrombosis (DVT) and Pulmonary Embolism (PE), where a clot travels to the lungs. A clot dislodging from a vein and traveling to an artery causes venous thromboembolism (VTE). A clot traveling to the heart can cause arterial fibrillation and one embolising in the brain will initiate a stroke. If a blood clot blocks blood flow to an organ, such as the kidney, heart or brain, it may cause irreversible damage (infarction) leading to organ failure.  

 

Within allopathic medicine D-Dimer testing is combined with other laboratory testing and scans to identify correct disease diagnosis and monitor progression, typically used to help exclude DVT and PE.

Where might I see raised levels of D-Dimer?

What do I need to know about testing and D-Dimer levels?

  • D-Dimer levels tend to increase with age.
  • Levels may also be progressively increased during pregnancy and so use of D-Dimer is not recommended as a marker during pregnancy.
  • Levels are higher in women vs men and black populations vs Caucasians. It is lowest in Asian populations (Zakai N A et al. 2017)

The effect of pregnancy on levels of D-Dimer

https://www.perinatology.com/Reference/Reference%20Ranges/D-Dimer.htm

The NHS uses cut-off reference ranges according to age:

Age (Years)     D-dimer (ng/ml) 
   <60                    <500 
   61-70                 <600 
   71-80                 <700 
   81-90                 <800 
   >90                    <900

Are false results a possibility with D-Dimer?

  • Anti-coagulant therapy can cause false negative D-Dimer.
  • False negative or falsely low results can occur with hyper lipaemia.
  • Rheumatoid factor seen in those with Rheumatoid Arthritis may cause high levels (Kyung Soon Song et al. 1999). (although evidence is conflicting)
  • Raised Bilirubin can cause false positives.
  • Haemolysis (rupturing of red blood cells) caused by improper collection and handling.

What other markers do I need to consider in relation to D-Dimer?

  • D-Dimer and CRP are both independent but additive risk markers for ischaemic heart disease (Lowe G D O et al. 2014).
  • D-Dimer has been shown to increase the release of inflammatory cytokines IL-6 and IL-1ß from in vitro monocytes. Plasminogen activator inhibitor bioactivity and Plasminogen activator inhibitor Antigen type 2 levels were also increased. (Robson S C et al. 1994).
  • In severely ill hospital patients, there is a link between increased inflammatory cytokines and increased D-Dimer levels. These are positively correlated with the severity of illness (Shorr et al. 2002).
  • Patients who are hospitalised with COVID and have raised inflammatory cytokines appear to be at increased risk of going on to develop raised D-Dimer and coagulopathy related to increased mortality (Poudel et al. 2021).

D-Dimer is available as an add on biomarker to any FDX panel.

Looking to understand the full picture of your clients health especially the risk of Cardiovascular issues? Discover FDX Cardio Check today