Anlei Liu

Background: Acute intermittent porphyria (AIP) is the most common and severe form of acute hepatic porphyria, caused by heterozygous mutations in the HMBS gene. Due to its non-specific clinical manifestations and low clinical awareness among clinicians, AIP is frequently misdiagnosed, leading to significant diagnostic delays and potentially fatal complications. Case presentation: We report a 20-year-old female patient who presented with a 9-month history of recurrent abdominal pain, paralytic ileus, unexplained liver injury, and hyponatremia, followed by progressive limb weakness. She was initially misdiagnosed with Guillain–Barré syndrome (GBS) and received intravenous immunoglobulin and systemic glucocorticoids. However, her condition deteriorated, and she developed life-threatening respiratory muscle paralysis requiring invasive mechanical ventilation. The diagnosis of AIP was confirmed by positive urinary porphobilinogen (PBG) testing and identification of the heterozygous HMBS c.517C>T pathogenic variant. The patient was treated with high-dose carbohydrate loading therapy and comprehensive supportive care, resulting in gradual clinical improvement. Discussion and Conclusions: This case exemplifies the substantial diagnostic challenges associated with AIP, especially when it manifests with peripheral neuropathy that closely mimics GBS. The triad of absent albuminocytologic dissociation in cerebrospinal fluid, preceding visceral symptoms, and inadequate response to standard first-line GBS therapy should immediately raise clinical suspicion for AIP. Enhanced clinical awareness of this rare disorder and timely implementation of urinary PBG screening are of paramount importance to prevent irreversible neurological complications and optimize long-term patient outcomes.