Sticky platelet syndrome

Overview

Sticky platelet syndrome (SPS) is a hereditary thrombophilic disorder characterized by an increased tendency of platelets to aggregate abnormally, leading to a higher risk of blood clot formation (thrombosis). It is considered one of the most common inherited causes of thrombophilia and can lead to recurrent venous and arterial thrombotic events, including deep vein thrombosis, pulmonary embolism, stroke, and pregnancy complications such as miscarriages.

The syndrome was first described in the 1980s and is defined by platelet hyperreactivity to low concentrations of agonists such as adenosine diphosphate (ADP) and epinephrine. SPS is usually inherited in an autosomal dominant pattern and may coexist with other thrombophilic conditions, increasing the overall risk of thrombosis.

Causes

The exact genetic cause of sticky platelet syndrome remains unclear, but it is thought to involve abnormalities in platelet membrane glycoproteins and signaling pathways that regulate platelet activation and aggregation. Factors contributing to SPS include:

• Genetic mutations affecting platelet receptors or signaling proteins

• Inherited defects in platelet function leading to hyperaggregability

• Environmental and acquired factors such as smoking, obesity, or hormonal therapy may exacerbate the condition

SPS is inherited in an autosomal dominant manner, so an affected individual usually has a parent with the disorder, though sporadic cases may occur.

Symptoms

Symptoms of sticky platelet syndrome are primarily related to thrombotic events caused by excessive platelet aggregation. These include:

• Recurrent deep vein thrombosis (DVT), causing pain, swelling, and redness, usually in the legs

• Pulmonary embolism, presenting with sudden shortness of breath, chest pain, or coughing up blood

• Ischemic stroke or transient ischemic attacks (TIA), leading to neurological deficits

• Recurrent pregnancy loss or complications such as preeclampsia and intrauterine growth restriction

• Less commonly, arterial thrombosis causing myocardial infarction or peripheral arterial disease

• In some cases, asymptomatic and diagnosed only after thrombotic events occur

Diagnosis

Diagnosis of sticky platelet syndrome involves specialized laboratory testing to assess platelet function, in addition to evaluation of clinical history. Diagnostic steps include:

• Platelet aggregometry: The gold standard test measuring platelet aggregation in response to low concentrations of ADP and epinephrine. SPS is diagnosed when platelets show hyperaggregation to these agonists.

• Exclusion of other causes: Tests to rule out other thrombophilias such as Factor V Leiden mutation, prothrombin gene mutation, protein C or S deficiency, and antiphospholipid syndrome.

• Coagulation profile: Including prothrombin time (PT), activated partial thromboplastin time (aPTT), and platelet count.

• Clinical evaluation: Detailed history of thrombotic events, family history, and pregnancy complications.

Treatment

Treatment of sticky platelet syndrome aims to prevent thrombotic events and manage existing clots. Approaches include:

• Antiplatelet therapy: Low-dose aspirin is the mainstay of treatment to reduce platelet aggregation and lower thrombosis risk.

• Anticoagulation: In patients with established thrombosis, anticoagulants such as warfarin or direct oral anticoagulants (DOACs) may be prescribed.

• Management of risk factors: Controlling hypertension, diabetes, avoiding smoking, and managing obesity.

• Pregnancy management: Close monitoring with low-dose aspirin and sometimes heparin to reduce pregnancy complications.

• Lifestyle modifications: Regular exercise and hydration to improve circulation.

Prognosis

With appropriate diagnosis and treatment, individuals with sticky platelet syndrome can manage their risk and lead normal lives. Antiplatelet and anticoagulant therapies significantly reduce the incidence of recurrent thrombotic events.

However, without treatment, SPS carries a high risk of serious complications such as stroke, pulmonary embolism, and pregnancy loss. Lifelong follow-up is generally recommended to monitor therapy effectiveness and adjust treatment as needed.