title: Refractory immune thrombocytopenia successfully treated with high-dose vitamin D supplementation and hydroxychloroquine: two case reports.
abstract: BACKGROUND
  Immune thrombocytopenic purpura is thought to be characterized by an immune response against the host's own platelets. If the thrombocytopenia is severe, patients are initially treated with high-dose steroids. Other more toxic second line treatments are considered if steroids fail. Here, we report the case of two patients in whom conventional treatment was unsuccessful but who responded to hydroxychloroquine and high-dose vitamin D replacement therapy. To the best of our knowledge, this is the first description of successful treatment for immune thrombocytopenia with high-dose vitamin D and hydroxychloroquine.
  
  
  METHODS
  Case 1: We report the case of a 79-year-old Caucasian man who presented with high titer antinuclear antibodies, positive anti-SSA/Ro autoantibodies and clinically was felt to have an overlap of systemic lupus erythematosus and/or Sjögren's syndrome with profound life-threatening thrombocytopenia. There was no evidence of underlying malignancy. The patient's platelet count significantly increased with vitamin D and hydroxychloroquine treatment, but upon vitamin D discontinuation his platelet levels plummeted. Hydroxychloroquine therapy was maintained throughout treatment. With reinstitution of high-dose vitamin D therapy, platelet counts were restored to normal levels.Case 2: We also report the case of an 87-year-old Caucasian woman who presented with high titer antinuclear antibodies, positive anti-SSA/Ro autoantibodies and was felt to have an overlap of systemic lupus erythematosus and/or Sjögren's syndrome with immune thrombocytopenia; she also had severely low levels of 25-hydroxy vitamin D (17ng/mL). There was no evidence of underlying malignancy. She responded to high-dose vitamin D replacement and hydroxychloroquine treatment, thereby alleviating the need for high-dose steroid treatment. She remains in remission while taking vitamin D, hydroxychloroquine and very low-dose prednisone. No untoward side effects were observed in either patient.
  
  
  CONCLUSIONS
  In our two case reports, we found an association between vitamin D deficiency and immune thrombocytopenia where platelet levels responded to vitamin D treatment and hydroxychloroquine but not to prednisone. We believe there may be synergism between vitamin D supplementation and hydroxychloroquine. The mechanism by which high-dose vitamin D results in increased platelet counts in immune thrombocytopenia patients is unknown. However, vitamin D has long been thought to play an immunomodulatory role, which may include a dampened immune response in patients with immune thrombocytopenia or other autoimmune diseases.
authors.affiliation: Arthritis Northwest, 16122 8th Ave SW, Seattle, WA, 98166, USA. bockowmd@gmail.com.
authors.forename: Barry
authors.initials: B
authors.lastname: Bockow
authors.forename: Tamara Bockow
authors.initials: TB
authors.lastname: Kaplan
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