Systemic lupus erythematosus and hydroxychloroquine-related acute intermittent porphyria

Porphyrias, particularly acute intermittent porphyria (AIP), are rare disorders which could be associated with systemic lupus erythematosus (SLE). Although the association with AIP has been known since 1952, only 11 cases have been published to date. It is widely known that precipitating causes such as infections, hormonal changes, sunlight exposure, stress and drugs could provoke an AIP crisis. Hydroxychloroquine (HCQ) is usually used in lupus patients, but rarely appears to trigger AIP crises even in SLE patients. The case of a 51-year-old man in whom AIP onset was probably due to hydroxychloroquine use during SLE management is presented. SLE onset was accompanied by fever, pleural, lung and joint involvement with a characteristic SLE autoantibody panel. Although prednisone was given, the joint symptoms did not subside. HCQ was then started; however, some days later the patient suffered anxiety, vomiting and severe abdominal pain refractory to pain-relief drugs and liver function had worsened. No cutaneous lesions were observed. The patient suffered similar episodes accompanied by paralytic ileus and dark-coloured urine, the sediment of which showed no abnormalities. In addition, no myoglobinuria was found. This finding raised the suspicion of AIP and urine tests revealed elevated values of delta-aminolevulinic acid and porphobilinogen. Hydroxychloroquine was preventively suspended and the patient improved notably within a few days. In the following months, the patient suffered no relapse and the prednisone dose could be lowered. Finally, a review of the literature on this topic highlighted the exceptional nature of an API/ SLE association particularly in men. Interestingly, porphyria may present first followed by SLE, or vice versa. The latency period between drug administration and disease onset varies from days to 2 years. Both chloroquine and HCQ may induce PAI in SLE patients. Clinicians should be alerted to a possible association with AIP when a patient with SLE recently put on HCQ presents acute onset of abdominal and/or neurological symptoms and dark urine. Appropriate tests and prompt HCQ cessation are mandatory.