Your Patient
A 16-year-old female presents with localized, severe acute abdominal pain, mainly at epigastric and periumbilical region with profuse vomiting.
Patient
history
Physical
exam
Laboratory and radiographic tests
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What Is the diagnosis?
Suspicion of acute intermittent porphyria (AIP) was confirmed when the porphobilinogen (PBG) urine test was strongly positive and quantitative urine PBG levels in 2 acute attacks were 5.51 and 31.5 mg/24 hours (normal: less than 2.4 mg/24 h).
Laboratory testing for AIP diagnosis
| Component | Normal condition (mg/24 hours) | On acute attack (mg/24 hours) | Reference values (mg/24 hours) |
|---|---|---|---|
| PBG | <0.9 | 31.5 | <2.4 |
PBG
Normal condition (mg/24 hours)
<0.9
On acute attack (mg/24 hours)
31.5
Reference values (mg/24 hours)
<2.4
Hematology for consultation.
Reference:
Júnior VRS, Lemos VMV, Feitosa IML, et al. Effect of Menstrual Cycle on Acute Intermittent Porphyria. Child Neurology Open. January 2017.
How do menstrual cycle hormones trigger AIP symptoms?
- Probably the main triggering factor for crisis is the menstrual cycle hormones.
- Progesterone is a porphyrins inductor and potent inducer of 5-aminolevulinic acid synthase 1, which is toxic to tissues when in high concentrations, and more phyrinogenic than estrogens, explaining the more frequent attacks in luteal phase of this patient’s menstrual cycle.
What makes this case so challenging?
- Repeat mutli-system symptoms
- No specific diagnosis after multitude of testing (lab and radiological)
Reference:
Júnior VRS, Lemos VMV, Feitosa IML, et al. Effect of Menstrual Cycle on Acute Intermittent Porphyria. Child Neurology Open. January 2017.
Key takeaways
Acute intermittent porphyria (AIP) is a rare inherited disease caused by a partial deficiency of the enzyme porphobilinogen (PBG) deaminase in the heme biosynthetic pathway.1
- PBG deficiency disrupts normal heme production, which leads to overproduction of porphyrin precursors.2
- Episodes of abdominal pain, the most common symptom, is usually severe, unremitting, and diffuse.1
Diagnosis of AIP is challenging because signs and symptoms mimic other, more common conditions.1
Accuracy and timeliness are important in the diagnosis of an acute porphyric attack.1
References:
- Anderson KE, Bloomer JR, Bonkovsky HL, et al. Recommendations for the Diagnosis and Treatment of the Acute Porphyrias. Ann Intern Med. 2005;142:439-450.
- Gonzalez-Arriaza HL, Bostwick JM. Am J Psych. 2003;160(3):450-458.
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