title: Evaluation of leukemia inhibitory factor as a marker of ectopic pregnancy.
abstract: OBJECTIVE
  Our purpose was to determine the utility of measuring serum leukemia inhibitory factor, a cytokine expressed in the process of pregnancy implantation, for the diagnosis of ectopic pregnancy.
  
  
  METHODS
  Serum samples from 40 patients with positive serum quantitative beta-human chorionic gonadotropin levels were used for leukemia inhibitory factor determination. The serum leukemia inhibitory factor concentration was determined by enzyme-linked immunosorbent assay in the following 4 groups: (1) normal intrauterine pregnancies, (2) threatened abortions, (3) spontaneous abortions, and (4) ectopic pregnancies.
  
  
  RESULTS
  All patients had detectable concentrations of leukemia inhibitory factor in serum, ranging from 2.44 to 8.25 pg/mL. Mean leukemia inhibitory factor concentrations for ectopic pregnancy were significantly lower (P <.05) than those of both the spontaneous abortion and threatened abortion groups by 1-way analysis of variance. When a cutoff point of serum leukemia inhibitory factor <6.2 pg/mL is assigned as diagnostic of ectopic pregnancy, leukemia inhibitory factor in patients with ectopic pregnancies versus all other groups predicted ectopic pregnancy with a sensitivity of 73%, specificity of 72%, positive predictive value of 50%, and negative predictive value of 88%.
  
  
  CONCLUSIONS
  Serum leukemia inhibitory factor concentration is lowest in patients with ectopic pregnancy. A cutoff point of 6.2 pg/mL maximizes the sensitivity and specificity of the test; however, it is not sufficiently discriminatory to be used clinically for the diagnosis of ectopic pregnancy.
authors.affiliation: Department of Obstetrics and Gynecology, College of Medicine, University of Cincinnati, Ohio, USA.
authors.forename: N T
authors.initials: NT
authors.lastname: Wegner
authors.forename: J L
authors.initials: JL
authors.lastname: Mershon
mesh_terms: D000022:Abortion, Spontaneous / Q000097:blood; D000033:Abortion, Threatened / Q000097:blood; D015415:Biomarkers; D005260:Female; D006131:Growth Inhibitors / Q000097:blood*; D006801:Humans; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000097:blood*; D009994:Osmolar Concentration; D011237:Predictive Value of Tests; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000097:blood* / Q000175:diagnosis*; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D006131:Growth Inhibitors; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines