From the Guidelines
Henoch-Schönlein purpura (HSP) typically does not cause thrombocytopenia, as normal platelet counts are a characteristic feature of this condition. HSP is an immune-mediated small vessel vasculitis characterized by IgA immune complex deposition in vessel walls, primarily affecting the skin, joints, gastrointestinal tract, and kidneys. The classic presentation includes palpable purpura (especially on the lower extremities and buttocks), abdominal pain, arthralgia, and potential renal involvement. Despite causing purpuric skin lesions that might suggest a platelet disorder, the purpura in HSP results from inflammation and damage to small blood vessels rather than from low platelet counts.
If thrombocytopenia is present in a patient with suspected HSP, clinicians should consider alternative or additional diagnoses such as idiopathic thrombocytopenic purpura (ITP), thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), or other conditions that can mimic HSP's presentation. The evaluation of a low platelet count should distinguish between true thrombocytopenia and pseudothrombocytopenia, which occurs in about 0.1% of adults; most commonly due to innocent platelet agglutinins that cause platelet clumping in the presence of the anticoagulant EDTA 1.
Key points to consider in the diagnosis and management of HSP and thrombocytopenia include:
- Normal platelet counts are a characteristic feature of HSP
- Thrombocytopenia in HSP may indicate an alternative or additional diagnosis
- Evaluation of thrombocytopenia should include consideration of pseudothrombocytopenia and other causes of low platelet count
- The principal elements of the history, physical examination, and initial blood counts and smear are crucial in distinguishing HSP from other conditions that may cause thrombocytopenia 1.
In terms of management, the focus should be on treating the underlying condition, whether it be HSP or another cause of thrombocytopenia. For HSP, treatment may involve supportive care, such as rest and hydration, as well as medications to manage symptoms such as pain and inflammation. In some cases, medications such as ACE inhibitors or ARBs may be used to treat renal involvement 1. However, the presence of thrombocytopenia may require additional or alternative treatment strategies, and clinicians should consider consulting with a hematologist or other specialist as needed.
From the Research
Henoch-Schönlein Purpura and Thrombocytopenia
- Henoch-Schönlein purpura (HSP) is characterized by a triad of palpable purpura, abdominal pain, and arthritis, and is typically associated with thrombocytosis rather than thrombocytopenia 2.
- Thrombocytosis is found in about 60% to 70% of patients with HSP, suggesting that thrombocytopenia is not a typical feature of the disease 3.
- The presence of thrombocytosis in HSP patients is thought to be a type of inflammatory reactive thrombocytosis, and interleukin-6 (IL-6) may play a role in the pathogenesis of HSP 3.
- Studies have reported that thrombocytosis is significantly associated with the presence of abdominal pain and gastrointestinal bleeding in HSP patients 4.
- There is no direct evidence to suggest that HSP is typically associated with thrombocytopenia, and the disease is often characterized by the absence of thrombocytopenia 2, 5.
Platelet Counts in HSP
- Mean platelet volume (MPV) concentrations have been found to be significantly lower in HSP patients compared to healthy controls, and MPV may be a useful marker to identify active disease in HSP patients 6.
- Significant negative correlations have been observed between MPV and neutrophil count, platelet count, and erythrocyte sedimentation rate in patients with HSP 6.
- These findings suggest that platelet counts and MPV may be altered in HSP patients, but do not provide direct evidence for the presence of thrombocytopenia in HSP.