Four forms of
porphyria may present clinically with the acute attack, an episodic, severe, and potentially life-threatening manifestation characterized by abdominal and
neurologic symptoms. We describe our experience with 112 consecutive attacks observed and treated in 25 patients with the 2 most common forms of
acute porphyria in Cape Town, South Africa; 25 attacks in 10 patients with
variegate porphyria and 87 attacks in 14 patients with
acute intermittent porphyria. The remaining patient experienced more than 100 sequential, severe, and poorly remitting attacks, which are not included in our analysis. In our population, the relative risk of an acute attack in
acute intermittent porphyria compared with that in
variegate porphyria was 14.3 (confidence intervals, 6.3-32.7). Patients with
variegate porphyria were significantly older (median age at first attack, 30 yr) than those with
acute intermittent porphyria (median age at first attack, 23.5 yr; p < 0.0001), and demonstrated an equal sex ratio, whereas the male:female ratio in
acute intermittent porphyria was 2:12 (p < 0.0001). There was a significant difference in the incidence of factors precipitating the acute attack.
Drug exposure was a frequent precipitant of the acute attack in
variegate porphyria, whereas hormonal factors were more important in
acute intermittent porphyria (p < 0.00001). Patients with
acute intermittent porphyria also showed a trend to earlier and more frequent recurrent acute attacks following the initial admission. Mean urine precursor levels, blood pressure, pulse rate, and
heme arginate requirement were all significantly higher in patients with
acute intermittent porphyria. No significant difference in the frequency of serious complications or in outcome could be shown. We describe our experience with treatment with
heme arginate, and provide evidence that
heme arginate results in a prompt and statistically significant improvement in symptoms. The incidence of serious complications and mortality in this series was low, confirming a trend to an increasingly good prognosis for patients with
acute porphyria who receive expert treatment.