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The Antiphospholipid Antibody Syndrome

This blog post is a follow up to a popular video on my YouTube channel on the antiphospholipid antibody syndrome (watch here). I am surprised to find so many people interested in learning about the antiphospholipid antibody syndrome. So, for those who prefer text over video, this blog post is for you. You can click the relevant links below to access other videos that explain highlighted concepts in more detail.

The antiphospholipid antibody syndrome is an autoimmune disorder

The antiphospholipid antibody syndrome is an autoimmune disorder. In autoimmune disorders, the body‘s defense mechanisms wrongly recognize normal body antigens (proteins that can induce an immune response) as foreign antigens and attack them. In the case of the antiphospholipid antibody syndrome, the immune system produces antibodies against phospholipids.

Phospholipids are important for blood clotting

When the body experiences injury in the form of a damage to a blood vessel, clotting mechanisms are activated to quickly repair the damage and return the body to homeostasis. Involved in this process are two major blood components, platelets and blood clotting (or coagulation) factors. Platelets are the agents of primary hemostasis, which means that they are the first responders to the site of injury. Coagulation factors mediate secondary hemostasis, which means that they come later to reinforce the platelets. First, platelets form a platelet plug, which plugs up the injury and temporarily restores hemostasis. However, the platelet plug is not very strong and needs reinforcement. Platelet plug reinforcement is done by coagulation factors. Coagulation factors assemble on the platelet surface to create a strong mesh or fibrin clot, which is eventually broken down through fibrinolysis. Coagulation factors assemble on the platelet surface. The platelet surface is the key to the functioning of coagulation factors because the platelet surface contains phospholipids.

When phospholipids are attacked by antibodies, clotting mechanisms go awry

Phospholipids on the platelet surface are a key ingredient for blood clotting. Therefore, when antibodies attack and destroy phospholipids, they affect blood clotting processes. Under normal circumstances in the absence of vessel injury, there is a good balance between bleeding and clotting mechanisms. When there is vessel wall injury that causes bleeding, the balance appropriately tips towards clotting until hemostasis is restored. However, when antiphospholipid antibodies attack phospholipids, they activate inflammatory processes that tip the balance towards clotting.

The antiphospholipid antibody syndrome presents with recurrent clotting events

People with antiphospholipid antibody syndrome tend to present with recurrent clotting events. These events are typically unexplained by the usual blood clotting risk factors, such as surgery, trauma, and cancer. People with antiphospholipid antibody syndrome can develop blood clots for reasons that are provoked; but they typically clot indiscriminately. These blood clotting events happen in many forms and include deep venous thrombosis, pulmonary embolism, stroke, or unusual blood clotting in the microcirculation (small blood vessels), which is manifested by low platelet counts or thrombocytopenia. Antiphospholipid antibody syndrome blood clotting events can also manifest as recurrent pregnancy loss, especially when the pregnancy loss occurs later in pregnancy.

The antiphospholipid antibody syndrome has specific diagnostic criteria

To make the diagnosis of antiphospholipid antibody syndrome, two things must be present: 1) A history of recurrent blood clotting events and/or recurrent late term pregnancy loss (or near misses) 2) Evidence of antibodies against phospholipids. The history of recurrent blood clotting is usually what leads people to consider the diagnosis in the first place. So, what seals the diagnosis is the presence of antiphospholipid antibodies.

Make the diagnosis by demonstrating antiphospholipid antibodies

There are numerous possible antiphospholipid antibodies. However, the best recognized and widely excepted tests as of this writing are anticardiolipin antibodies and anti-beta 2 glycoprotein 1 antibodies. Therefore, antiphospholipid antibody testing involves looking specifically for these antibodies and measuring their levels. The testing measures levels of the antibody isotypes, IgA, IgG, or IgM. In the clinical setting, IgG and IgM antibodies are the most significant of these antibodies. The clinical significance of IgA antibodies is not well understood. Another way to demonstrate antiphospholipid antibodies is to do a lupus anticoagulant panel.

The lupus anticoagulant panel detects antiphospholipid antibodies

The lupus anticoagulant panel is an indirect way of testing for antiphospholipid antibodies. The lupus anticoagulant panel make use of the fact that many blood clotting assays (like the activated partial thromboplastin time or aPTT) only work in the presence of phospholipids. If antiphospholipid antibodies are present in the blood sample, they will affect the phospholipids in the clotting assay and cause a false prolongation of the clotting time. Therefore, a lupus anticoagulant is simply an antiphospholipid antibody that is interfering with the phospholipids in the clotting assay, thereby prolonging the clotting time.

Antiphospholipid antibodies can disappear

Antiphospholipid antibodies can be transient, meaning they can come and go. Therefore, finding an antiphospholipid antibody alone is not a definitive diagnosis of antiphospholipid antibody syndrome, especially in the absence of blood clotting events. For instance, many people in the general population have antiphospholipid antibodies without any blood clotting problems. Also, many people have blood clotting problems with low titer antiphospholipid antibody levels. Therefore, to make the diagnosis of antiphospholipid antibody syndrome, in addition to blood clotting events, antiphospholipid antibodies must persist. They must persist for a minimum of 12 weeks. For this reason, 12 weeks is the minimum amount of time required between antiphospholipid antibody testing to confirm the diagnosis.

The antiphospholipid antibody syndrome is managed with anticoagulation

Since the main problem with the antiphospholipid antibody syndrome is recurrent blood clotting events, the primary treatment is anticoagulant therapy. Usually, people with antiphospholipid antibody syndrome are anticoagulants for the rest of their lives. Not all anticoagulants work equally well to prevent blood clotting with antiphospholipid antibody syndrome. Therefore, people with antiphospholipid antibody syndrome work with their hematologist to determine the best anticoagulant for them. Even with the best anticoagulant, breakthrough blood clotting events can occur. Therefore, people with anti-phospholipid antibody syndrome also need to work with their providers to determine the right dose of their anticoagulant and what, if any, additional agents are needed.

But what about the autoimmune disorder?

Yes, the antiphospholipid antibody syndrome is an autoimmune disorder; but no, treatment of the autoimmune disorder is not typically at the forefront of therapy. When people present with blood clotting events, the first point of action is to address the blood clotting problem. However, if somebody presents with an antiphospholipid antibody crisis (catastrophic antiphospholipid antibody syndrome), treatment of the immune phenomena is typically initiated immediately alongside treatment of the blood clotting event. Long term treatment of the autoimmune disorder should be discussed with a hematologist. However, as at the time of this writing, there is no known cure.

My antiphospholipid antibody syndrome wish list

In the management of anti-phospholipid antibody syndrome, I wish for three things:

  1. Better diagnostic testing. Some people with antiphospholipid antibody syndrome present with unusual clotting manifestations, some of which are non-specific. Some unusual manifestations of micro thrombosis (in small blood vessels) include abdominal pain, difficulty breathing, and low platelets. These non-specific symptoms are not clearly thrombotic presentations and it takes weeks to make the diagnosis. For this reason, I wish for better diagnostic testing that cuts down the time to making a diagnosis.

  2. More effective therapies. Antiphospholipid antibody syndrome typically manifests with recurrent blood clotting events even when patients are appropriately anticoagulated. Perhaps we need better anticoagulants. However, I think the biggest wins will come from treating the autoimmune disorder. Can we address the underlying autoimmune phenomenon and eliminate the need for long-term anticoagulant medications, which, over time, are associated with bleeding complications. Antiphospholipid antibody syndrome is an autoimmune disorder. Therefore, we need more effective autoimmune therapies to treat the underlying autoimmune problem

  3. Strategies to increase adherence. Many (but not all) of my patients who develop recurrent blood clotting events have a recurrent event because they stopped (or paused) their anticoagulants. Taking a pill every day is burdensome and in many cases, crazy expensive. And when you tell someone that they have to take one pill consistently for the rest of their lives, without missing a dose, that’s very difficult, if not impossible. When my patients present with recurrent thrombosis, it is sometimes (though not always) because they’re not taking their medication. My first wish is to cure the antiphospholipid antibody syndrome and get rid of it completely. However, until the cure, I wish I could figure out how to help people stay consistent with their therapies so that the risk of a major clotting event is decreased.

In summary, the antiphospholipid antibody syndrome is a serious blood clotting disorder that should be diagnosed as soon as possible and managed with the help of a hematologist who specializes in bleeding and clotting disorders. Until a cure is achieved, people should work with their hematologist to find an anticoagulation plan that works and then stick with the plan.

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