Question: How common is thrombocytopenia as a presenting feature of systemic lupus?

Answer:

It has been estimated that 3–15% of patients with apparently isolated Immune thrombocytopenia (ITP) go on to develop SLE.1 Mild thrombocytopenia (platelet counts between 100,000 and 150,000/µL) has been noted in 25–50% of patients, while counts of less than 50,000/µL occur in only 10%.2-4 There are several potential causes of thrombocytopenia in patients with systemic lupus erythematosus (SLE). Immune-mediated platelet destruction is most often the cause, increased platelet consumption due to a thrombotic microangiopathy (thrombotic thrombocytopenic purpura), the APS, antibodies that block the thrombopoietin receptor on megakaryocytes or their precursors, or may be due to impaired platelet production as a result of the use of cytotoxic, immunosuppressive, or other drugs are other important causes of thrombocytopenia in systemic lupus.

References

1. Karpatkin S. Autoimmune thrombocytopenic purpura. Blood. 1980;56:329.
2. Monrad SU, Kaplan MJ. Cellular hematology. In: Lahita R, Tsokos G, Buyon J, Koike T. (eds). Systemic Lupus Erythematosus, 5th edn, Amsterdam: Elsevier and Academic Press, 2011.
3. Newman K, Owlia MB, El-Hemaidi I, Akhtari M. Management of immune cytopenias in patients with systemic lupus erythematosus - Old and new. Autoimmun Rev. 2013;12:784.
4. Keeling DM, Isenberg DA. Haematological manifestations of systemic lupus erythematosus. Blood Rev. 1993;7:199.