Acute intermittent porphyria

In this chapter we briefly outline the haem biosynthetic pathway and how deficiencies in individual enzymes give rise to the different porphyrias. We then describe the clinical features and diagnosis of AIP, followed by a discussion of pathogenesis, highlighting advances in the molecular biology of AIP and introducing the debate as to whether neurovisceral crises might result from porphyrin precursor neurotoxicity or from haem deficiency. Finally we discuss management, including family screening, avoidance of triggering factors, analgesia, maintenance of a high calorie intake, and administration of haem derivatives.