The predictive value of five different urinary LH kits in detecting the LH surge in regularly menstruating women

OBJECTIVES: To compare the predictive value of five different urinary LH kits at detecting the LH surge in regularly menstruating, reproductive-age women. DESIGN: Single center, prospective study. SETTING: University of Tennessee, Obstetrics and Gynecology department. INTERVENTION: Eleven regularly menstruating women collected urine daily from cycle days 10 through 18. Urinary LH was quantitated by radioimmunoassay. Transvaginal sonography was performed to document ovulation. Three different lots of Clear Plan Easy, OvuKit, OvuQuick, Sure Step, and EZ LH were evaluated. MAIN OUTCOME MEASURE: Correlation of urinary LH test kit results with urine LH value determined by RIA. RESULTS: Peak urinary LH values by RIA ranged from 13.5 mIU/mL to 73.0 mIU/mL. The lowest level detected as positive by LH kits ranged from 25.5 mIU/mL to 48.7 mIU/mL. Lot-to-lot variations were rare. Follicular collapse occurred within 24 hours of the urinary LH peak in 8 of 10 (80%) and by 48 hours in the remaining 2 subjects. CONCLUSIONS: The percentage of LH surges detected by urinary LH kits ranged from 50% to 100%. The lowest LH value detected as positive varied almost twofold between different kits. Manufacturers should indicate the detection limit of their kits in mIU/mL.