01.Diagnosis of deep vein thrombosis and pulmonary embolism

Deep vein thrombosis (D-VT) is prone to pulmonary embolism (PE), collectively known as venous thromboembolism (VTE). Plasma D-dimer levels are significantly elevated in VTE patients.

Related studies have shown that the plasma D-dimer concentration in patients with PE and D-VT is greater than 1 000 μg/L.

However, due to many diseases or some pathological factors (surgery, tumors, cardiovascular diseases, etc.) have a certain impact on hemostasis, resulting in increased D-dimer. Therefore, although D-dimer has high sensitivity, its specificity is only 50% to 70%, and D-dimer alone cannot diagnose VTE. Therefore, a significant increase in D-dimer cannot be used as a specific indicator of VTE. The practical significance of D-dimer testing is that a negative result precludes the diagnosis of VTE.

 

02 Disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a syndrome of extensive microthrombosis in small vessels throughout the body and secondary hyperfibrinolysis under the action of certain pathogenic factors, which may be accompanied by secondary fibrinolysis or inhibited fibrinolysis.

The elevated plasma content of D-dimer has a high clinical reference value for the early diagnosis of DIC. However, it should be noted that the increase of D-dimer is not a specific test for DIC, but many diseases accompanied by microthrombosis may lead to the increase of D-dimer. When fibrinolysis is secondary to extravascular coagulation, D-dimer will also increase.

Studies have shown that D-dimer begins to rise days before DIC and is significantly higher than normal.

 

03 Neonatal asphyxia

There are different degrees of hypoxia and acidosis in neonatal asphyxia, and hypoxia and acidosis can cause extensive vascular endothelial damage, resulting in the release of a large amount of coagulation substances, thereby increasing the production of fibrinogen.

Relevant studies have shown that the D-dimer value of cord blood in the asphyxia group is significantly higher than that of the normal control group, and compared with the D-dimer value in peripheral blood, it is also significantly higher.

 

04 Systemic lupus erythematosus (SLE)

The coagulation-fibrinolysis system is abnormal in SLE patients, and the abnormality of the coagulation-fibrinolysis system is more pronounced in the active stage of the disease, and the tendency of thrombosis is more obvious; when the disease is relieved, the coagulation-fibrinolysis system tends to be normal.

Therefore, the D-dimer levels of patients with systemic lupus erythematosus in active and inactive stages will be significantly increased, and the plasma D-dimer levels of patients in active stage are significantly higher than those in inactive stage.

05 Liver cirrhosis and liver cancer

D-dimer is one of the markers reflecting the severity of liver disease. The more severe the liver disease, the higher the plasma D-dimer content.

Relevant studies showed that the D-dimer values ​​of Child-Pugh A, B, and C grades in patients with liver cirrhosis were (2.218 ± 0.54) μg/mL, (6.03 ± 0.76) μg/mL, and (10.536 ± 0.664) μg/mL, respectively. .

In addition, D-dimer was significantly elevated in patients with liver cancer with rapid progression and poor prognosis.

06 Stomach cancer

After resection of cancer patients, thromboembolism occurs in about half of patients, and D-dimer is significantly increased in 90% of patients.

In addition, there is a class of high-sugar substances in tumor cells whose structure and tissue factor are very similar. Participating in human metabolic activities can promote the activity of the body's coagulation system and increase the risk of thrombosis, and the level of D-dimer is significantly increased. And the level of D-dimer in gastric cancer patients with stage III-IV was significantly higher than that in gastric cancer patients with stage I-II.

 

07 Mycoplasma pneumonia (MMP)

Severe MPP is often accompanied by elevated D-dimer levels, and D-dimer levels are significantly higher in patients with severe MPP than in mild cases.

When MPP is seriously ill, hypoxia, ischemia and acidosis will occur locally, coupled with the direct invasion of pathogens, which will damage vascular endothelial cells, expose collagen, activate the coagulation system, form a hypercoagulable state, and form microthrombi. The internal fibrinolytic, kinin and complement systems are also activated successively, resulting in increased D-dimer levels.

 

08 Diabetes, diabetic nephropathy

D-dimer levels were significantly elevated in patients with diabetes and diabetic nephropathy.

In addition, the D-dimer and fibrinogen indexes of patients with diabetic nephropathy were significantly higher than those of type 2 diabetes patients. Therefore, in clinical practice, D-dimer can be used as a test index for diagnosing the severity of diabetes and kidney disease in patients.

09 Allergic Purpura (AP)

In the acute phase of AP, there are different degrees of blood hypercoagulability and enhanced platelet function, leading to vasospasm, platelet aggregation and thrombosis.

Elevated D-dimer in children with AP is common after 2 weeks of onset and varies between clinical stages, reflecting the extent and degree of systemic vascular inflammation.

In addition, it is also a prognostic indicator, with persistently high levels of D-dimer, the disease is often prolonged and prone to renal damage.

 

10 Pregnancy

Related studies have shown that about 10% of pregnant women have significantly elevated D-dimer levels, suggesting a risk of blood clots.

Preeclampsia is a common complication of pregnancy. The main pathological changes of preeclampsia and eclampsia are coagulation activation and fibrinolysis enhancement, resulting in increased microvascular thrombosis and D-dimer.

D-dimer decreased quickly after delivery in normal women, but increased in women with preeclampsia, and did not return to normal until 4 to 6 weeks.

11 Acute Coronary Syndrome and Dissecting Aneurysm

Patients with acute coronary syndromes have normal or only mildly elevated D-dimer levels, whereas aortic dissecting aneurysms are markedly elevated.

This is related to the significant difference in the thrombus load in the arterial vessels of the two. The coronary lumen is thinner and the thrombus in the coronary artery is less. After the aortic intima ruptures, a large amount of arterial blood enters the vessel wall to form a dissecting aneurysm. A large number of thrombi are formed under the action of the coagulation mechanism.

12 Acute cerebral infarction

In acute cerebral infarction, spontaneous thrombolysis and secondary fibrinolytic activity are increased, manifested as increased plasma D-dimer levels. The D-dimer level was significantly increased in the early stage of acute cerebral infarction.

Plasma D-dimer levels in patients with acute ischemic stroke were slightly increased in the first week after onset, significantly increased in 2 to 4 weeks, and were not different from normal levels during the recovery period (>3 months).