A comparison of blood spot vs. plasma analysis of gonadotropin and ovarian steroid hormone levels in reproductive-age women

ObjectiveTo compare LH, FSH, P, and E2 levels obtained from blood spot vs. plasma (single-visit study) and to determine whether blood spots can document circulating hormone levels during ovulatory cycles (menstrual-cycle study).DesignCross-sectional study.SettingAcademic center.Patient(s)Women 18–35 years of age with regular menstrual cycles and no recent use of hormonal contraception.Intervention(s)Women contributed both a blood spot sample from a finger-stick and a plasma sample through venipuncture on a random day within their menstrual cycle (n = 100, single study visit). Five additional women were followed for an entire menstrual cycle with biweekly venipuncture and daily self-collected blood spot sampling. Samples were analyzed for FSH, LH, P, and E2.Main Outcome Measure(s)Correlation between blood spot and plasma levels.Result(s)Significant positive correlations were found between the blood spot and plasma samples in the single-visit study (r2: FSH, 0.91; LH, 0.93; P, 0.83; and E2, 0.70). Two of the 5 menstrual-cycle study women had ovulatory cycles based on P levels (>3 ng/mL) and an LH surge. Daily blood spot sampling was better able to document hormonal changes than biweekly venipuncture.Conclusion(s)Blood spot monitoring of FSH, LH, P, and, to a lesser extent, E2, appears to be as valid as traditional plasma assays for clinical research and care.