Are the levels of UTXB2 higher in women due to hormonal differences? In a prior pilot study we investigated whether hormonal levels are associated with changes in urinary thromboxane. We looked at hormonal and urinary thromboxane levels in 48 postmenopausal and 52 premenopausal women. We found that postmenopausal women had higher levels of UTXB2 than did premenopausal women (2495 vs. 2299, p=.02) and that in premenopausal women a higher estrogen/progesterone ratio was associated with the highest levels of urinary thromboxane.