Acute intermittent porphyria in women: clinical expression, use and experience of exogenous sex hormones. A population-based study in northern Sweden.

Objective: To describe the clinical expression of acute intermittent porphyria (AIP) in women, their use of exogenous sex hormones, and the effects on AIP.
Design: A retrospective population-based study.
Subjects: All women aged > or =18 years (n = 190) with DNA-diagnosed AIP in northern Sweden.
Results: A total of 166 women (87%) participated; 91 (55%) had manifest AIP. Severe attacks were reported by 82%; 39% reported recurrent premenstrual AIP attacks and 22% reported chronic AIP symptoms. Oral hormonal contraceptives had been used by 58% of all these women and by 50 with manifest AIP (57%). Twelve women (24%) associated oral contraceptives as precipitating AIP attacks; in nine cases their first attack. One woman experienced relief from AIP symptoms. On commencing their treatment, 72% of the women with manifest AIP had not yet suffered their first attack. Twenty-two women (25%) aged > or =45 years had used hormonal replacement therapy (HRT) at menopause to remedy climacteric symptoms (the percutaneous route was most frequently used); no AIP attack was precipitated. HRT to remedy vaginal dryness was used by 26 women (28%) aged > or =45 years without triggering an AIP attack. Miscarriages were more frequent in women with manifest AIP (50%) than in the latent group (30%, P = 0.014).
Conclusions: About half of the women with AIP had used oral hormonal contraceptives. As 25% of women with manifest AIP reported attacks associated with such drugs, caution must still be recommended. Menopausal HRT only rarely affected the disorder. Miscarriage was more common amongst women with manifest AIP.