When does heparin-induced thrombocytopenia occur
Symptoms usually appear 5 days to 2 weeks after starting taking heparin. HIT can also occur at other times.
Early onset HIT occurred 1 - 3 days after starting taking heparin. This early form of HIT occurred in the past (usually within the past three months) when taking heparin. When this happens, your body will "remember" heparin because it has been exposed to heparin. It has produced antibodies against heparin and can start to react.
Refractory (persistent) HIT continued for several weeks after discontinuation of heparin.
Delayed HIT does not occur until heparin is stopped. It starts five days or more after you stop taking medicine.
What causes heparin-induced thrombocytopenia?
HIT occurs when heparin binds to a protein called PF4 in platelets. Heparin and PF4 form the so-called complex. The compound is named heparin-PF4 according to its components (heparin and PF4). The presence of heparin pf4 will trigger your immune system to produce antibodies. These antibodies bind to heparin - pf4. Once the antibody is attached, your platelets begin to clot.
Coagulating platelets release more PF4, causing a chain reaction. In other words, the newly released PF4 combines with more heparin to produce more heparin-PF4. Antibodies combine with heparin - pf4, causing more coagulation, etc.
All coagulation will deplete your platelets. Therefore, your platelet level will drop. All blood clots will cause huge, life-threatening blood clots to block your veins and arteries.
What are the risk factors of heparin-induced thrombocytopenia?
Risk factors of HIT include:
Gender: HIT is more common in women and AFAB population.
Take some forms of heparin: Some studies have shown that the form of heparin you take may reduce your risk of HIT. Taking undivided heparin instead of LMWH may reduce your risk. More research is needed to determine.
Taking heparin after surgery: people who receive heparin to prevent thrombus after surgery are more likely to have HIT than those who receive thrombus treatment. Orthopedic surgery, cardiac surgery and cardiopulmonary bypass surgery are all associated with the increased risk of heparin-induced thrombocytopenia.
How to diagnose heparin-induced thrombocytopenia?
Blood tests can show whether you have HIT. Blood test measurement:
Platelet level: Your platelet level indicates whether you have low platelet count or thrombocytopenia.
Blood clot formation: A blood test can show whether your blood is forming blood clots.
PF4 antibody level: The amount of PF4 antibody level in the blood can confirm that your immune system is activating platelets. The antibody test confirmed the HIT diagnosis.
Your healthcare provider may also arrange ultrasound to check your leg for thrombus (deep vein thrombosis, DVT). Depending on your situation, your healthcare provider may image other parts, such as your arm, to check for blood clots.
The antibody test results may take some time to confirm that you have HIT. Because HIT can be fatal if it is not treated, your doctor will not wait to receive the results before starting treatment. Instead, they will decide whether to start treatment according to your likelihood of HIT.
