Diagnosis and Treatment of Acute Intermittent Porphyria

Acute intermittent porphyria is a disorder of haem synthesis which is associated with attacks of neurologic dysfunction. The disease is due to an inherited defect in the third enzyme of haem synthesis, porphobilinogen deaminase. The importance of an exact diagnosis, on the basis of urinary amino-laevulinic acid, and porphobilinogen excretion, faecal porphyrin content, and erythrocyte porphobilinogen deaminase activity is stressed. In some families the genetic variation in porphobilinogen deaminase activity requires the use of DNA techniques for firm diagnosis. Treatment is symptomatic. Haem arginate or haematin intravenously is useful in the acute attack. Tin-protoporphyrin, which is a competitive inhibitor of haem breakdown, is a promising new addition to the treatment of the acute attack.