Hepatic Adenomas in Adolescents and Young Women with Endometriosis Treated with Norethindrone Acetate

Background: Endometriosisdectopic implantation of endometrial-like tissuedaffects 10% of female adolescents and adults. First-line treatment includes progesterone only (such as norethindrone acetate [NET-A]) or combined estrogen/progestin oral contraceptive pills. Estrogen-containing contraceptives confer increased risk of hepatic adenomas, whereas the association with NET-A is very rarely reported. Case: Three adolescents with stage I to II endometriosis managed with NET-A (up to 15 mg/d for 28-78 months) were diagnosed with hepatic adenomas at ages 17-22 years. They previously received estrogen-containing medications, which were stopped 24 months or longer before diagnosis of hepatic adenoma. Summary and Conclusion: NET-A in a dose greater than 10 mg/d might be associated with increased risk for hepatic adenomas, likely due to peripheral conversion to ethinyl estradiol. Use of NET-A might not be advisable in patients with known hepatic adenomas.