Received on April 28, 2005
Accepted on July 7, 2005

Endocrinology and Metabolism

Diagnostic Considerations in the Measurement of Human Chorionic Gonadotropin in Aging Women

¹ Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC
² Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO

^* To whom correspondence should be addressed. E-mail: dgrenach{at}unch.unc.edu.

Background: Human chorionic gondadotropin (hCG) screening tests are frequently performed on female patients of childbearing age before any medical intervention that could potentially harm a fetus. Although older women usually have negative hCG test results, positive results do occur and may cause clinical confusion. We examined changes with age in serum hCG concentrations in nonpregnant women and investigated the use of serum follicle-stimulating hormone (FSH) measurements as an aid to interpreting higher than expected ("positive") hCG results.

Methods: We used 240 serum specimens for each of 4 female cohorts: pregnant, 18 years; nonpregnant, 18-40 years (premenopausal); nonpregnant, 41-55 years (perimenopausal); and nonpregnant, >55 years (postmenopausal). Patients were excluded if they had an ectopic pregnancy, a history of trophoblastic disease, or a germ-cell tumor, or if no chart was available for review. Quantitative hCG and FSH tests were performed on each specimen.

Results: Serum hCG concentrations in nonpregnant women increased with the age of the women. hCG concentration results were higher and significantly different (P <0.0001) for nonpregnant women >55 years (<2.0 to 13.1 IU/L) compared with nonpregnant women 18-40 years (<2.0 to 4.6 IU/L) and 41-55 years (<2.0 to 7.7 IU/L). Nineteen nonpregnant women >40 years of age had hCG concentrations 5.0 IU/L, all with an FSH concentration >32.4 IU/L. The highest FSH concentration in pregnancy was 7.3 IU/L.

Conclusions: Serum hCG increases with age in nonpregnant women. A cutoff of 14.0 IU/L should be used when interpreting hCG results in women >55 years of age. Pregnancy is unlikely in perimenopausal women 41-55 years of age with an hCG between 5.0 and 14.0 IU/L if serum FSH is >20.0 IU/L.