Hereditary angio-oedema: effective treatment with the progestogen-only pill in a young woman

Sir, A 24‐year‐old woman was admitted in February 2000, for an attack of hereditary angio‐oedema (HA). Her sister had weekly episodes of laryngeal oedema; her father and her paternal grandfather also had episodes of oedema which were never investigated. Her past medical history was unremarkable except for appendectomy when she was aged 5 years. Since the age of 9 years, she had had one or two episodes of HA each year, each lasting 2–3 days, with swelling of the arms, abdominal pain and low blood pressure, without upper airways swelling. Serum analysis confirmed the diagnosis of type I HA, showing low C1 esterase inhibitor (C1 INH) and C4 antigenic levels. She had never been treated with danazol. Between 1994 and 1998 she had remained symptom free while she was taking a progestogen‐only pill for birth control (norgestrienone 0·35 mg daily). Since she stopped taking the pill in August 1998, she had five attacks of HA. In February 2000, she was admitted for swelling of the right arm and the left foot. Blood tests showed a decrease of C1 INH functional activity (< 10% of normal value) associated with low C4 (41 mg L−1; normal 93–380) and C1 INH antigenic levels (54 mg L−1; normal 170–540), whereas C3 level (682 mg L−1; normal 660–1250) was normal. The attack resolved spontaneously. Norgestrienone was prescribed again. The patient has remained symptom free since then. Two months after starting treatment with norgestrienone, C1 INH functional activity increased to 22% of normal value, and C1 INH and C4 antigenic levels increased to 80 mg L−1 and 76 mg L−1, respectively.