Abstract
OBJECTIVE: To compare LH, FSH, P, and E(2) 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). DESIGN: Cross-sectional study. SETTING: Academic 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 E(2). 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 (r(2): FSH, 0.91; LH, 0.93; P, 0.83; and E(2,) 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, E(2), appears to be as valid as traditional plasma assays for clinical research and care.