Case Presentation: A 21-year-old otherwise healthy female army recruit undergoing basic training was admitted to an outside hospital with severe abdominal pain, nausea, and vomiting. An abdominal CT was unremarkable. Laboratory results revealed hyponatremia (Na 117mmol/L) and polycythemia (Hgb 17mg/dL). Patient then developed severe chest pain associated with tachycardia, hypertension and a mild troponin elevation. Transthoracic echo and CT PE were unremarkable. Based on the constellation of her symptoms and laboratory results (abdominal pain, tachycardia, HTN, hyponatremia, polycythemia) workup for acute intermittent porphyria (AIP) was initiated and she was transferred to our hospital for further management.Upon presentation to our hospital, patient was in moderate distress due to abdominal pain and had hypertension, tachycardia, and severe deconditioning. The rest of the exam was unremarkable with no neurological deficits. Laboratory results were remarkable for Na of 126mmol/L, hemoglobin of 15.6mg/dL, and urinary studies consistent with SIADH. The patient was started on daily intravenous hemin. She was also treated symptomatically for her abdominal pain and nausea and fluid restricted due to her SIADH. Her symptoms gradually improved, labs and vitals normalized, and IV hemin was stopped. The patient was discharged with full resolution of her symptoms.
Post discharge her laboratory results returned showing elevated urine porphobilinogen, elevated urine ALA, and low levels of RBC porphobilinogen deaminase.
Based on the clinical presentation and final laboratory results the diagnosis of AIP was made.
Discussion: AIP is an acute neurovisceral porphyria resulting from a partial deficiency of the heme biosynthetic enzyme porphobilinogen deaminase (PBGD). Diagnosing AIP is difficult because the symptoms are variable, nonspecific and the disease is rare.
Diagnosis is made based on elevated levels of random urine PBG. Additionally, low levels of erythrocyte PBGD are present in 90% of cases of AIP but genetic testing is required for definitive confirmation of AIP.
The treatment is IV hemin, discontinuation of known triggers, and supportive care. Treatment is continued until resolution of symptoms.
There are various triggers for AIP attacks. In the case above the patient’s attack was likely triggered by a combination of psychological stress from boot camp, relative calorie deficiency, and recently prescribed TMP-SMX.
Conclusions: AIP requires a high index of suspicion, and should be considered in a patient with otherwise unexplained neurovisceral symptoms, especially if previous similar and recurrent symptoms have been reported. Early diagnosis and treatment is crucial as severe attacks of AIP can lead to bulbar paralysis, respiratory impairment and death. Elevated urine porphobilinogen levels are sufficient to initiate treatment and treatment should not be delayed pending confirmatory testing.