Objective: To investigate the relationship between thrombopoetin (TPO) serum levels and HIV-associated thrombocytopenia.
Design and methods: The relationship between TPO levels and severity of HIV-associated thrombocytopenia was investigated. Thirty-eight patients (19 patients with 30-96x10(9) platelets/l and 19 patients with <10x10(9) platelets/l) were matched with 38 HIV-positive non-thrombocytopenic patients (>150x10(9) platelets/l).
Results: HIV-positive patients with normal platelet counts had a median TPO serum level of 137 pg/ml. Patients with 30-96x10(9) platelets/l had decreased TPO levels with a median of 90 pg/ml (P = 0.016), and were more likely to have elevated serum aspartate-transferase levels (P<0.001) and hepatomegaly by palpation or ultrasound imaging (P = 0.005). The median TPO serum level of HIV-infected patients with severe thrombocytopenia was 110 pg/ml (non-significant). All patients with severe thrombocytopenia were positive for antibodies against hepatitis B virus core antigen, compared with 80% of HIV-infected persons without thrombocytopenia. Patients with severe thrombocytopenia were more likely to have high HIV replication compared to patients with normal platelet counts (P = 0.02), and reduction of plasma HIV-1 RNA levels was associated with increasing platelet counts. Severe thrombocytopenia was not associated with liver disease.
Conclusions: Liver disease predisposes for low TPO serum levels and mild thrombocytopenia. High retroviral activity predisposes for severe, immune thrombocytopenic purpura-like thrombocytopenia. At least two distinct categories of severe HIV-associated thrombocytopenia exist, one responsive to antiretroviral treatment and one non-responsive to antiretroviral treatment.