Random serum progesterone threshold to confirm ovulation R. Leiva a,b,⇑ , T. Bouchard c , H. Boehringer d , S. Abulla e,f,g,h , R. Ecochard e,f,g,h a Bruyère Research Institute, CT Lamont Primary Health Care Research Centre, 43 Bruyère St, K1N 5C8 Ottawa, Canada b University of Ottawa, Department of Family Medicine, 43 Bruyère St, K1N 5C8 Ottawa, Canada c Department of Family Medicine, University of Calgary, Calgary, Alberta, Canada d DCN Diagnostics, Carlsbad, CA, USA e Hospices Civils de Lyon, Service de Biostatistique, F-69003 Lyon, France f Université de Lyon, F-69000 Lyon, France g Université Lyon 1, F-69100 Villeurbanne, France h CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, Equipe Biostatistique-Santé, F-69100 Villeurbanne, France article info Article history: Received 12 January 2015 Received in revised form 18 June 2015 Accepted 18 June 2015 Available online 22 June 2015 Keywords: Menstrual cycle Progesterone Ovulation Infertility Fertility awareness methods Ultrasound abstract Background: Serum progesterone (P) rises after ovulation in the luteinisation process. Objective: To identify an accurate progesterone threshold to confirm ovulation in the assessment of a woman’s fertility. Methods: In a secondary analysis of an observational European multicentre study, this study included 107 women over 326 menstrual cycles and tracked daily first morning urine (FMU), changes in observed cervical mucus discharge, serum progesterone, and ultrasonography to identify the day of ovulation. A serum progesterone level was available for 102 women over a total 260 cycles with one or two P levels per cycle. Results: It was found that a single serum P P 5 ng/ml is highly specific with a specificity of 98.4 (95% CI 96.0–99.5), with a sensitivity of 89.6 (95% CI 85.2–92.9). Conclusion: A random serum progesterone level P5 ng/ml confirms ovulation. This may be of use for clinicians wanting to confirm that ovulation has occurred. Ó 2015 Elsevier Inc. All rights reserved. 1. Introduction Confirmation of ovulation is an essential component in the eval- uation of women experiencing fertility problems. Chronic anovula- tion is associated with increased risks of infertility, endometrial cancer, and osteoporosis [1]. While daily transvaginal ultrasound is the gold standard for documenting ovulation, it is too invasive or expensive to be used on a routine basis. Alternatively, a single mid-luteal phase serum progesterone level greater than 3 ng/ml has long been proposed as the second best indication of ovulation [2,3]. Nevertheless, it is well known that there is variability in ran- dom single blood samples for progesterone because levels can increase in response to the LH pulsations occurring after ovulation, which in turn is determined by the pulsatility of gonadotropin-re- leasing hormone (GnRH) secretion by the hypothalamus [8]. For this reason, we attempted to determine the lowest progesterone threshold to identify ultrasound-confirmed ovulation. In a previous study, we identified a method to confirm ovula- tion using urinary pregnanediol measurements [4]. While urinary measurements can be done in a home setting, a single random urine test may not be as accurate as a single random serum mea- surement in confirming ovulation. Thus, in the present study we identify a single random serum progesterone threshold to confirm ovulation. A single value that would minimize the misclassification of ovulation would be clinically useful in the assessment of a woman’s fertility. The main goal of this study was thus to achieve a low false positive rate, that is, highest specificity, to ensure the confirmation of ovulation. 2. Methods 2.1. Patients Patients were recruited from 1996 to 1997 from eight natural family planning clinics in France, Italy, Germany, Belgium, and Spain as previously reported [4]. A database of information was created but due to legal–commercial disclosure agreements with the funding company (Quidel Corporation), the results regarding http://dx.doi.org/10.1016/j.steroids.2015.06.013 0039-128X/Ó 2015 Elsevier Inc. All rights reserved. ⇑ Corresponding author at: Bruyère Continuing Care, 43 Bruyère Street, Ottawa, ON K1N 5C8, Canada. E-mail address: Rene.leiva@mail.mcgill.ca (R. Leiva). Steroids 101 (2015) 125–129 Contents lists available at ScienceDirect Steroids journal homepage: www.elsevier.com/locate/steroids