Kinetics of testosterone metabolism in normal postmenopausal women and women with breast cancer |
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Authors: | CE Bird W Finnis K Boroomand J Murphy AF Clark |
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Institution: | Departments of Medicine and Biochemistry, Queen''s University and Kingston General Hospital, Kingston, Ontario, K7L 3N6, Canada |
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Abstract: | The constant infusion and single injection techniques were utilized to study the kinetics of 3H-testosterone (T) metabolism in postmenopausal women with and without breast cancer. The metabolic clearance rates (mean ± SEM) for normal postmenopausal women were as obtained by the constant infusion and single injection techniques, respectively. The corresponding results for the women with breast cancer (patients) are . The single injection technique yielded values for rate constants (units) and volumes of distribution (1); k1 = 37.5 ± 1.6 for the normals and 34.5 ±1.9 for the patients. K2 = 76.6 ± 5.1 for the normals and 71.1 ± 1.6 for the patients, V1 = 7.9 ± 2.2 for the normals and 8.7 ± 1.4 for the patients and V2 = 7.0 ± 1.5 for the normals and 6.4 ± 1.2 for the patients. The constant infusion technique yielded values for the conversion ratios for the transformation of T to several products; 4-androstene-3,17-dione/T of 0.02 ± 0.003 for normals and 0.03± 0.002 for patients, 5α-dihydrotestosterone/T of 0.02 ± 0.002 for normals and 0.03 ± 0.002 for patients, estrone/T of 0.04 ± 0.01 for normals and 0.04 ± 0.01 for patients, estradiol-17β/T of 0.02 ± 0.005 for normals and 0.03 ± 0.005 for patients and estrone sulfate/T of O.16 ± 0.02 for normals and 0.24 ± 0.06 for patients. The T plasma concentrations and production rates were similar for the two groups of subjects. Hence there were no significant differences between the normals and the patients for all the kinetic parameters. It was determined that all the estradiol being produced in postmenopausal women could be coming from circulating T. |
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