title: Establishing reference intervals for hCG in postmenopausal women.
abstract: BACKGROUND
  Plasma concentrations of human chorionic gonadotropin (hCG) have been shown to increase with age due to pituitary secretion. We previously recommended that an hCG cutoff of 14.0IU/L be used for women ≥55years of age. However, it remains unknown whether concentrations >14.0IU/L can be expected in women with advanced age. Our objectives were to establish plasma hCG reference intervals and correlate follicle stimulating hormone (FSH) and hCG concentrations in postmenopausal females ≥55years.
  
  
  METHODS
  Residual plasma samples from 798 women ≥55years were utilized with 303, 269, and 226 samples belonging to the age groups 55-69, 70-84, and ≥85years, respectively. FSH and hCG were measured using the Abbott ARCHITECT. All positive hCG samples (hCG ≥5IU/L) were analyzed for potential heterophile antibody interference and 3 were excluded. Electronic medical records were reviewed and patients with malignancy were excluded.
  
  
  RESULTS
  8% (56/666) of women age≥55years had plasma hCG ≥5IU/L. There were 19, 16, and 21 patients with hCG ≥5IU/L in the age groups 55-69, 70-84, and ≥85years, respectively. The highest hCG concentrations observed in each age group were: 55-69years maximum=11.7IU/L and 97.5th percentile=9.6IU/L; 70-84years maximum=18.09IU/L, 97.5th percentile=6.2IU/L; ≥85years maximum=11.1IU/L and 97.5th percentile=10.0IU/L, and the overall 97.5th percentile=8.5IU/L for all women ≥55years of age. Neither hCG nor FSH concentrations continued to increase with age in women ≥55years.
  
  
  CONCLUSIONS
  The prevalence of positive hCG in women ≥55years is 8%. This study confirms our previously recommended cutoff of 14IU/L for women ≥55years of age. In women ≥55years of age, FSH concentrations do not predict hCG concentrations.
authors.affiliation: Division of Laboratory and Genomic medicine, Washington University School of Medicine, St. Louis, MO, United States.
authors.forename: Khushbu K
authors.initials: KK
authors.lastname: Patel
authors.affiliation: Division of Laboratory and Genomic medicine, Washington University School of Medicine, St. Louis, MO, United States.
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Qavi
authors.affiliation: Division of Laboratory and Genomic medicine, Washington University School of Medicine, St. Louis, MO, United States.
authors.forename: Karl G
authors.initials: KG
authors.lastname: Hock
authors.affiliation: Division of Laboratory and Genomic medicine, Washington University School of Medicine, St. Louis, MO, United States. Electronic address: gronowski@wustl.edu.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Gronowski
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D006063:Chorionic Gonadotropin / Q000097:blood*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D012016:Reference Values
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin; D005640:Follicle Stimulating Hormone