title: Antithrombin III: Plasma Activity and Reference Range Among Nigerian Blood Donors.
abstract: BACKGROUND
  Diagnosis of antithrombin III (ATIII) deficiency as a common cause of thrombophilia is primarily based on the determination of antithrombin levels in plasma using a functional activity assay or an immunological assay, but local reference interval is lacking.
  
  
  OBJECTIVE
  The aim of the present study was to determine pattern of antithrombin activity and local reference intervals for ATIII among Nigerians.
  
  
  METHODS
  A cross-sectional study was carried out among healthy blood donors at the Lagos University Teaching Hospital in Nigeria between the age range 18 and 65 years. Structured questionnaires were applied to obtain demographic and clinical history. Percentage ATIII activity was determined using immunoassay technique. Data were analysed using SPSS version 20.0.
  
  
  RESULTS
  One hundred and fifty-five healthy blood donors who participated in this study consisted of 84 males and 71 females. The mean age of participants was 35 ± 6.7 years with a modal age range at 25-49 years. The mean percentage ATIII activity was 91.2 ± 14.2% (confidence interval: 69.2-113.2). Reference interval estimated for all the subjects was 62.8-119.6%. ATIII activity was lower in females compared to males (91.1 vs. 94.2; P = 0.03). However, ATIII activity tended to decrease with increasing age (P = 0.001).
  
  
  CONCLUSIONS
  Mean percentage ATIII activity for our study population was 91.2% with a reference interval of 62.8-119.6%. Reference interval for ATIII activity in African population is lower than documented Caucasian values.
authors.affiliation: From the Department of Haematology and Blood Transfusion, College of Medicine, University of Lagos, Nigeria.
authors.forename: Vincent Oluseye
authors.initials: VO
authors.lastname: Osunkalu
authors.forename: Okezie Obasi
authors.initials: OO
authors.lastname: Kanu
authors.forename: Felix
authors.initials: F
authors.lastname: Ngwuli