title: Immature platelet fraction levels in a variety of bone marrow pathologies in South African HIV-positive patients with thrombocytopenia.
abstract: OBJECTIVE
  Thrombocytopenia is common in HIV-infected individuals and often requires a diagnostic bone marrow examination. Interpretation may, however, be limited due to the multifactorial nature of HIV-associated thrombocytopenia and the difficulty in assessing megakaryocyte function morphologically. The immature platelet fraction (IPF) is a parameter which reportedly reflects megakaryocyte activity, with an IPF >7.7% suggesting increased platelet production. The aim of this study was to correlate the IPF with the bone marrow findings as well as other clinical variables of interest in South African patients with HIV-associated thrombocytopenia.
  
  
  METHODS
  Seventy-eight HIV-positive patients with thrombocytopenia were enrolled from the Charlotte Maxeke Johannesburg Academic Hospital. The IPF levels were measured using a Sysmex XE-5000 haematology analyzer and were correlated with bone marrow and other findings.
  
  
  RESULTS
  The median IPF was 7.6%, ranging from 1.3 to 44%. It was raised in 78% of patients with immune thrombocytopenia (ITP) (median = 16.3%) and low in 79% of patients with hypocellular marrow (median = 6.5%). Surprisingly, it was highly variable among patients with malignant marrow infiltration and mycobacterial infection of the bone marrow (BMTB) (median = 8.4 and 7.1%, respectively). Multivariate linear regression analysis confirmed a significant independent inverse relationship between the IPF and hypocellular marrow (P < 0.0001), a marginally significant positive association with ITP (P = 0.059), and the absence of any relationship with malignant infiltration or BMTB. The IPF had a significant inverse association with the platelet count (P = 0.0006), but was unrelated to the CD4 count and exposure to anti-retroviral therapy. Unexpectedly, it showed a significant positive association with the HIV viral load (P = 0.005). We speculate this to reflect increased megakaryocyte activity in compensation for accelerated platelet clearance due to HIV-driven platelet activation.
  
  
  CONCLUSIONS
  This study investigates the role of the IPF in HIV-associated thrombocytopenia, and emphasizes the limitations of morphological analysis in determining megakaryocyte function.
authors.forename: Jenifer
authors.initials: J
authors.lastname: Vaughan
authors.forename: Tracey
authors.initials: T
authors.lastname: Wiggill
authors.forename: Marion
authors.initials: M
authors.lastname: Munster
mesh_terms: D000328:Adult; D001855:Bone Marrow Diseases / Q000097:blood* / Q000821:virology; D002452:Cell Count; D005260:Female; D015658:HIV Infections / Q000097:blood* / Q000821:virology; D006801:Humans; D016014:Linear Models; D008297:Male; D055016:Megakaryocyte Progenitor Cells / Q000473:pathology*; D008533:Megakaryocytes / Q000473:pathology; D015999:Multivariate Analysis; D010976:Platelet Count; D013019:South Africa; D013921:Thrombocytopenia / Q000097:blood* / Q000821:virology; D019562:Viral Load
keywords: HIV; IPF; Immature platelet praction; Sysmex; Thrombocytopenia