Objectives: To assess the association between acute intermittent porphyria (AIP), hypertension and renal disease.
Design: A population-based matched case-control study (1:4) in 50 AIP patients (manifest/latent 25/25), a retrospective study of all individuals who died between the years 1978 and 1990 (2122 including 33 with AIP) and a group of eight patients with severe AIP.
Results: Hypertension was found in 56% of patients with manifest AIP, 33% of their controls (P = 0.041) and 16% of patients with latent AIP (P = 0.004). Renal disease was not more common in patients with AIP than in their controls. Three of the eight patients with severe recurrent AIP had impaired renal function, caused in one by systemic lupus erythematosus (SLE) nephritis. In the other two, no cause other than AIP could be found. In the mortality study, hypertension was registered in 68% of patients with manifest AIP compared to 21% of those with latent AIP (P = 0.008) but death from myocardial infarction and stroke was not more common. Uraemia was cited as the cause of death in 9.1% of AIP patients and 1.0% of those without AIP (P = 0.006).
Conclusions: Hypertension is more common in patients with manifest AIP than in those with latent AIP or control subjects. Renal disease may be due to hypertension, to AIP or to SLE. AIP may predispose to other renal diseases.