Onset of Acute Intermittent Porphyria After Etonogestrel Implant Insertion: A Case Report

A 17-year-old previously healthy female developed posterior reversible encephalopathy syndrome 1 week after etonogestrel implantation. She had a previous etonogestrel implant removed 4 months prior after unrelenting abdominal pain and hyponatremia with a negative workup for other etiologies, including hypercoagulable disorders and malignancy. This second insertion and resulting hospitalization allowed for the diagnosis of acute intermittent porphyria (AIP) to be confirmed. Progesterone can induce enzymatic activity upstream of porphobilinogen deaminase, the enzyme implicated in AIP, resulting in build-up of toxic metabolites. AIP requires high clinical suspicion for diagnosis but should be considered when hormonal triggers lead to unexplained neurovisceral symptoms.