Acute Intermittent Porphyria—A Diagnostic Dilemma

Abstract

Porphyrias are metabolic diseases resulting from a partial deficiency of an enzyme in the heme biosynthetic pathway. AIP (deficiency of hydroxymethylbilane synthase) causes acute attacks due to secondary accumulation of heme precursors. It presents with abdominal pain, tachycardia, hypertension, hyponatremia, seizures, motor neuropathy, etc. Screening is done with qualitative urinary PBG and ALA. Urinary and fecal fractionated porphyrins and DNA testing provided the confirmation. Acute attacks are treated with IV hemin and glucose. Prevention of acute attacks is with smoking cessation and avoidance of inciting agents. A 11-year-old undernourished girl, on multiple antiepileptics, for 4 years (started for refractory seizures), presented with complaints of recurrent generalized abdominal pain with weight loss since the past 1 year, with constipation and poor oral acceptance since 10 days. Examination revealed tender epigastrium, decreased air entry on left side of chest, generalized muscle wasting, and paresthesias. Investigations revealed Hb 9 g/dl; TLC 8200/cu mm (77/ 20/01/02); platelets 1,84,000/cu mm; PS-normocytic normochromic; Na 131 meq/L; K 4 meq/L; Ca 8.9 mg/dl; PO4 3.3 md/dl; ALP 255 U/L; blood urea 49 mg/dl; serum creatinine 0.9 mg/dl; bilirubin 0.5 mg/dl; SGOT 54 U/L; SGPT 21 U/L; blood culture—no growth; HIV-NR; urine examination— normal; serum amylase 112U/L; serum lipase 71U/ L; lipid profile, carbamazepine level, and CXR—normal; PPD test –NR; GA for AFB—negative; USG abdomen, CECT abdomen, and brain—normal; CECT thorax-opacities and necrotic patches on left lower zone consistent with pulmonary tuberculosis; EEGpartial epilepsy with focus at right temporal lobe; serum lead level—normal; Urine for porphobilinogen, 5-ALA, and total porphyrins—positive; and NCV— Severe axonal motor and sensory neuropathy in all four limbs. A diagnosis of AIP with pulmonary tuberculosis with partial seizure with undernutrition was made. Antiepileptics were tapered gradually and gabapentine with modified ATT was started and the child responded very well. AIP should be kept in the differentials of chronic abdominal pain and patients with psychological symptoms.