The effect of add-back treatment with tibolone (Livial) on patients treated with the gonadotropin-releasing hormone agonist triptorelin (Decapeptyl).

Objective: To assess whether tibolone can prevent the bone loss and symptomatic side effects normally associated with GnRH agonist (GnRH-a) use and whether tibolone modifies the effect of GnRH-a on endometriosis.

Design: Prospective, double-blind, placebo-controlled, group comparative study.

Setting: Gynecological research unit in a London teaching hospital.

Patients: Twenty-nine patients with endometriosis and two with fibroids.

Interventions: Six months of treatment with 3.75 mg/mo IM triptorelin combined with daily tablets of either placebo or 2.5 mg tibolone.

Main Outcome Measures: Daily symptom diary for hot flushes and bleeding episodes, laparoscopic scoring of endometriosis, endocrine and biochemical changes, and bone mineral density scans.

Results: Lumbar spine bone mineral density decreased significantly from baseline in the placebo group (-5.1%) but not in the tibolone group (-1.1%). The frequency of hot flushes and sweating episodes was reduced significantly by tibolone. There was no difference between the two treatment groups with regard to the endometriosis scores.

Conclusions: The addition of tibolone to GnRH-a treatment reduces the bone loss and vasomotor symptoms that normally occur with GnRH-a, thus making long-term treatment with GnRH-a safer and more acceptable. It does not negate the therapeutic effect of GnRH-a on endometriosis.