A longitudinal study of plasma and urinary cortisol in pregnancy and postpartum

Caroliine jung, Jui Ho, David Torpy, Anne Rogers, Matthew Doogue, John lewis, Raymond Czajko, warrick inder

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    173 Citations (Scopus)

    Abstract

    Context: There is a paucity of longitudinal data on plasma and urinary cortisol levels during pregnancy using modern assays. Furthermore, conflicting data exist as to the effect of the low-dose oral contraceptive pill (OCP) on cortisol. Design, Subjects, and Measurements: We conducted a prospective longitudinal study on morning plasma cortisol (total and free), corticosteroid-binding globulin (CBG), and 24-h urinary free cortisol (UFC) levels in 20 pregnant women during the first, second, and third trimesters and 2-3 months postpartum compared with 12 subjects on low-dose OCP and 15 nonpregnant subjects not taking the OCP (control group). Results: A progressive rise in total plasma cortisol, CBG, and 24-h UFC was demonstrated during pregnancy, peaking during the third trimester (mean 3-fold rise compared with controls). Plasma free cortisol increased 1.6-fold by the third trimester. In the OCP group, total plasma cortisol and CBG were 2.9- and 2.6-fold elevated, respectively, whereas 24-h UFC and plasma free cortisol were not significantly different from controls. Compared with liquid chromatography-mass spectrometry, a commercial immunoassay underestimated mean total plasma cortisol concentrations by 30% during second and third trimesters and in OCP users and overestimated UFC levels by 30-35% during pregnancy. Conclusions: Our study demonstrated elevations in total plasma cortisol and CBG concentrations during pregnancy and with low-dose OCP use. Pregnancy was also associated with significant increases in plasma free cortisol and UFC, suggesting that the rise in total plasma cortisol is contributed to by up-regulation of the maternal hypothalamic-pituitary-adrenal axis in addition to elevated CBG.

    Original languageEnglish
    Pages (from-to)1533-1540
    Number of pages8
    JournalJournal of Clinical Endocrinology and Metabolism
    Volume96
    Issue number5
    DOIs
    Publication statusPublished - May 2011

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