Co-occurring autoimmune conditions may warrant lupus screening

Immune thrombocytopenia (ITP) can occur in people with antiphospholipid syndrome (APS), another immune disorder — and people who have co-occurring ITP and APS almost always have a third co-occurring autoimmune disease, lupus.

That’s according to the study, “Immune thrombocytopenia is rare in patients with antiphospholipid syndrome without systemic lupus erythematosus: insights from a series of 351 patients,” which was published in Lupus Science & Medicine.

Based on the findings, researchers advised screening for lupus in patients who have co-occurring APS and ITP.

ITP is driven by antibodies that destroy platelets, cell fragments that help blood clot. Low platelet levels (thrombocytopenia) can lead to thrombocytopenia symptoms such as abnormally easy and prolonged bleeding.

APS causes clots to form in blood vessels. It’s relatively common for people with APS to develop thrombocytopenia. Most of the time, low platelet levels in APS occur because platelets are being sucked up into disease-related blood clots. That can be due to catastrophic APS or CAPS, a life-threatening form of APS that results in the failure of multiple organs. But it’s also possible for people with APS to have co-occurring ITP. Distinguishing between CAPS and co-occurring ITP can be tricky, but it’s essential to ensure that patients receive appropriate thrombocytopenia treatment.

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Looking for causes

Scientists in France reviewed data from 102 people with APS who had thrombocytopenia to better understand the factors driving low platelet levels in APS.

“To date, no study has ever analysed in detail the [causes] of thrombocytopenia in patients with APS,” they wrote.

The scientists found that, in nearly three-quarters of the APS patients, thrombocytopenia was triggered by CAPS. Twelve patients had co-occurring ITP, including two who had CAPS and ITP at the same time.

Lupus is another autoimmune disease driven by antibodies that attack the body’s own healthy tissues. Slightly fewer than half of the APS patients in the study had co-occurring systemic lupus erythematosus, the most common form of lupus. Among the 12 APS patients with co-occurring ITP, almost all also had lupus. In fact, among all patients, only two had co-occurring APS and ITP without lupus.

“Interestingly, patients with ITP [but not lupus] were exceptionally uncommon in our cohort,” the researchers wrote. They said this highlights “the importance of screening for [lupus] or alternative cause of thrombocytopenia in such cases.”