title: Iron status determination in pregnancy using the Thomas plot.
abstract: BACKGROUND
  Physiological changes during pregnancy affect routine tests for iron deficiency. The reticulocyte haemoglobin equivalent (RET-He) and serum-soluble transferrin receptor (sTfR) assay are newer diagnostic parameters for the detection of iron deficiency, combined in the Thomas diagnostic plot. We used this plot to determine the iron status of pregnant women presenting for their first visit to an antenatal clinic in Bloemfontein, South Africa.
  
  
  METHODS
  Routine laboratory tests (serum ferritin, full blood count and C-reactive protein) and RET-He and sTfR were performed. The iron status was determined using the Thomas plot.
  
  
  RESULTS
  For this study, 103 pregnant women were recruited. According to the Thomas plot, 72.8% of the participants had normal iron stores and erythropoiesis. Iron-deficient erythropoiesis was detected in 12.6%. A third of participants were anaemic. Serum ferritin showed excellent sensitivity but poor specificity for detecting depleted iron stores. HIV status had no influence on the iron status of the participants.
  
  
  CONCLUSIONS
  Our findings reiterate that causes other than iron deficiency should be considered in anaemic individuals. When compared with the Thomas plot, a low serum ferritin is a sensitive but nonspecific indicator of iron deficiency. The Thomas plot may provide useful information to identify pregnant individuals in whom haematologic parameters indicate limited iron availability for erythropoiesis.
authors.affiliation: Department of Haematology and Cell Biology, Faculty of Health Sciences, University of the Free State and National Health Laboratory Service (NHLS), Bloemfontein, South Africa.
authors.forename: R
authors.initials: R
authors.lastname: Weyers
authors.affiliation: Department of Haematology and Cell Biology, Faculty of Health Sciences, University of the Free State and National Health Laboratory Service (NHLS), Bloemfontein, South Africa.
authors.forename: M J
authors.initials: MJ
authors.lastname: Coetzee
authors.affiliation: Department of Biostatistics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa.
authors.forename: M
authors.initials: M
authors.lastname: Nel
mesh_terms: D000293:Adolescent; D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000175:diagnosis; D015415:Biomarkers; D001772:Blood Cell Count; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D005293:Ferritins / Q000097:blood; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007501:Iron / Q000097:blood / Q000378:metabolism*; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic; D012156:Reticulocytes / Q000378:metabolism*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D006454:Hemoglobins; D002097:C-Reactive Protein; D005293:Ferritins; D007501:Iron
keywords: Pregnancy; anaemia; ferritin; iron deficiency; reticulocytes