Teen’s Abdominal Pain and Seizures Lead to Rare AIP Diagnosis — Porphyria News

A 16-year-old girl from Ohio was diagnosed with acute intermittent porphyria (AIP) after months of unexplained abdominal pain and neurological symptoms, including seizures, led doctors to consider a rare metabolic disorder. The case, reported by Porphyria News and confirmed through genetic testing at a regional medical center, highlights how the nonspecific presentation of AIP can delay diagnosis despite available biochemical tests.

Acute intermittent porphyria is one of several inherited disorders affecting heme biosynthesis, a process essential for producing hemoglobin and other vital molecules. In AIP, a deficiency in the enzyme porphobilinogen deaminase leads to the accumulation of toxic precursors like aminolevulinic acid (ALA) and porphobilinogen (PBG), which can trigger acute attacks characterized by severe abdominal pain, vomiting, hypertension, tachycardia, and neurological symptoms such as anxiety, confusion, seizures, and muscle weakness.

The teen’s symptoms began approximately six months before diagnosis, with recurring episodes of intense abdominal pain that initially prompted evaluations for gastrointestinal conditions such as appendicitis, irritable bowel syndrome, and pelvic inflammatory disease. When standard treatments failed and neurological symptoms emerged — including two generalized tonic-clonic seizures — physicians ordered urine screening for porphyrin precursors during an acute episode.

Elevated levels of ALA and PBG in the urine raised suspicion for an acute hepatic porphyria. Subsequent genetic analysis confirmed a pathogenic mutation in the HMBS gene, which encodes porphobilinogen deaminase, establishing the diagnosis of AIP. The patient had no prior family history of porphyria reported, though clinicians noted that penetrance can be incomplete and family screening is often recommended following an index case.

According to the American Porphyria Foundation, acute hepatic porphyrias like AIP affect an estimated 5 in 100,000 people worldwide, with many cases remaining undiagnosed due to symptom overlap with more common conditions. Attacks are frequently triggered by factors such as certain medications (including barbiturates, sulfonamides, and some hormonal contraceptives), fasting, stress, and hormonal changes — particularly relevant in adolescents and young adults.

Treatment for acute AIP focuses on stopping the attack and managing symptoms. Intravenous glucose or hemin (Panhematin®) is used to suppress the overproduction of heme precursors via negative feedback on hepatic heme synthesis. In this case, the teen received hemin infusion during hospitalization, which led to gradual symptom resolution over several days. She was also advised to avoid known triggers and was placed on a preventive regimen under the care of a metabolic specialist.

Long-term management of AIP includes lifestyle modifications and, for those with frequent attacks, prophylactic therapies. Givosiran (Givlaari®), a small interfering RNA medication approved by the U.S. Food and Drug Administration in 2019, reduces hepatic ALAS1 expression and has been shown to decrease the frequency of porphyria attacks in patients with recurrent disease. However, its use is typically reserved for individuals with multiple acute attacks per year due to cost and potential side effects.

Experts emphasize that early recognition of AIP is critical to prevent complications such as chronic pain, neuropathic symptoms, and, in rare cases, progressive motor weakness resembling Guillain-Barré syndrome. Delayed diagnosis increases the risk of unnecessary surgeries — the teen had undergone one exploratory laparotomy prior to diagnosis — and exposure to unsafe medications that can provoke or worsen attacks.

Following diagnosis, the patient’s immediate family members were offered genetic testing to identify potential carriers of the HMBS mutation. While most individuals with the mutation remain asymptomatic, awareness of carrier status allows for informed decisions regarding medication use and trigger avoidance, particularly during periods of heightened risk such as puberty, pregnancy, or illness.

This case underscores the importance of considering rare metabolic disorders in the differential diagnosis of unexplained recurrent abdominal pain accompanied by neuropsychiatric symptoms. Although AIP is uncommon, timely urine screening during an acute attack — a simple, low-cost test — can prevent prolonged suffering and guide appropriate treatment. Increased awareness among emergency physicians, gastroenterologists, and neurologists may help reduce diagnostic delays for this treatable but potentially life-threatening condition.