Comparison of the effect of oral and transdermal hormone therapy on fasting and postmethionine homocysteine levels.

Objective: To compare the modifications on basal and post-methionine homocysteine (Hcy) levels induced by transdermal vs. oral continuous combined hormone therapy (HT).

Design: Prospective randomized study.

Setting: Outpatient service at university hospital.

Patient(s): Twenty-four healthy postmenopausal women.

Intervention(s): Six-month administration of transdermal (50 microg/d of E(2) and 140-170 microg/d of norethisterone [NET] acetate; n = 12) or oral (2 mg of E(2) and 1 mg of NET acetate; n = 12) HT.

Main Outcome Measure(s): Fasting levels of Hcy, cysteine (Cys), folate, and vitamin B12. Post-methionine Hcy concentrations.

Result(s): During HT, a slight decrease of fasting Hcy (8.9 [6.7; 15.2] micromol/L vs. 8.3 [4.9; 12.0] micromol/L) and fasting Hcy/Cys, a possible index of Hcy trans-sulfuration (0.061 [0.039; 0.107] micromol/L vs. 0.048 [0.032; 0.093] micromol/L) was observed. Modifications were similar in the transdermal and oral group. Net decreases of Hcy and Hcy/Cys observed during HT were related linearly to pretreatment values (r = 0.821 and r = 0.775, respectively), and were significant for Hcy above, but not below, 9 micromol/L. Transdermal (33.5 [27.5; 75.9] micromol/L vs. 28.4 [17.4; 48.9] micromol/L) or oral HT (36.1 [17.7; 74.8] micromol/L vs. 29.9 [17.5; 50.3] micromol/L), decreased, similarly, post-methionine Hcy levels.

Conclusion(s): Similarly to oral, transdermal HT reduces post-methionine Hcy and fasting Hcy when it is elevated.