Establishing reference intervals for hCG in postmenopausal women

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 14.0 IU/L be used for women >= 55 years of age. However, it remains unknown whether concentrations >14.0 IU/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 >= 55 years. Methods: Residual plasma samples from 798 women >= 55 years were utilized with 303, 269, and 226 samples belonging to the age groups 55-69, 70-84, and >= 85 years, respectively. FSH and hCG were measured using the Abbott ARCHITECT. All positive hCG samples (hCG >= 5 IU/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 >= 55 years had plasma hCG IU/L. There were 19, 16, and 21 patients with hCG >= 5 IU/L in the age groups 55-69, 70-84, and >= 85 years, respectively. The highest hCG concentrations observed in each age group were: 55-69 years maximum = 11.7 IU/L and 97.5th percentile = 9.6 IU/L; 70-84 years maximum = 18.09 IU/L, 97.5th percentile = 6.2 IU/L; >= 85 years maximum = 11.1 IU/L and 97.5th percentile = 10.0 IU/L, and the overall 97.5th percentile = 8.5 IU/L for all women >= 55 years of age. Neither hCG nor FSH concentrations continued to increase with age in women >= 55 years. Conclusions: The prevalence of positive hCG in women >= 55 Years is 8%. This study confirms our previously recommended cutoff of 14 IU/L for women >= 55 years of age. In women years of age, FSH concentrations do not predict hCG concentrations. (C) 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.