Plasma and urinary sex hormones are differently related to lipids in healthy postmenopausal women.

Objective: Endogenous sex hormones can be measured in plasma and urine. We determined the extent to which these two methods provide different information on hormonal status by relating them to lipid profile in postmenopausal women.

Methods: Thirty healthy postmenopausal women collected one 24-h urine sample and a blood sample was taken. Urinary estrone (UE), plasma estrone (PE) and serum lipids were measured. Sex hormone levels were measured with specific radioimmunoassays. Linear regression analysis was used to determine associations between estrone levels and lipids. Results are presented as beta-coefficients in mmol/l per standard deviation (SD) of endogenous estrone levels, adjusted for body mass index (BMI) and smoking (95% confidence interval). A stratified analysis for obese (BMI> or =27 kg/m(2)) versus lean women was performed.

Results: Mean levels of endogenous sex hormones were (SD): PE, 90.1 pmol/l (37.3); and UE, 7757 pmol/24 h (2659). PE showed significant associations with HDL-cholesterol (0.18 mmol/l, 95% CI: 0.06; 0.30), triglycerides (-0.25 mmol/l, 95% CI: -0.49; -0.009) and very-low-density-lipoprotein (VLDL-cholesterol) (-0.11 mmol/l, 95% CI: -0.22; -0.003), but not with total and low-density-lipoprotein (LDL-cholesterol). UE was inversely associated with total (-0.41 mmol/l, 95% CI: -0.85; 0.02) and LDL-cholesterols (-0.42 mmol/l, 95% CI: -0.83; -0.005), but not with HDL-cholesterol, triglycerides and VLDL-cholesterol. All associations appeared to be stronger in lean women.

Conclusion: Both plasma and UE levels appear to be associated to serum lipids in healthy postmenopausal women. However, this relation appears to be different for estrone levels in plasma and urine. Depending on the research question, either blood samples or urine samples may be preferred.