A 14‐year‐old boy with mental retardation, seizure disorder, and spastic quadriplegia was admitted with a 5 day history of lethargy, constipation, and reddish urine. He also had increased seizure frequency, which was usually controlled on lamitrogine, phenobarbital, and valproic acid. Review of systems was otherwise negative. He had documented normal blood pressures in the clinic on previous visits. On admission, his heart rate was 117 and blood pressure 181/98. Labs were significant for sodium of 121. normal potassium, and a mild hypochloremic metabolic alkalosis. Creatinine was normal. Urinalysis was negative. A workup for hypertension was negative, including complement levels, renin, aldosterone, ANA, and renal ultrasound with Doppler. During the hospitalization, his mental status improved, electrolytes corrected with mild fluid restriction, and his hypertension was controlled with labetolol. He was discharged and weaned off the labetolol within 3 months. Approximately 1 year after the first hospitalization, he again presented with 5 days of lethargy constipation, and reddish urine. Blood pressure at that time was 171/119. Sodium was 122 with mild hypochloremic alkalosis. Because of the acute onset and episodic pattern of symptoms with complete resolution in between, and because of the reddish‐brown urine, urine and serum porphyrins were sent, which were elevated. In addition, both urine porphobilinogen and delta‐aminolevulinic acid were very elevated. The diagnosis of acute intermittent porphyria was made. He was weaned off of his phenobarbital and valproic acid, which are known to exacerbate porphyria, and started on levetiracetam for seizure control. His electrolytes and blood pressure normalized.
The acute porphyrias are extremely rare in childhood. Acute intermittent porphyria is the most common type, although it rarely presents in childhood. They may be particularly difficult to diagnose in mentally retarded children who are unable to express symptoms of abdominal pain or peripheral neuropathy. Common presenting symptoms include abdominal pain, tachycardia, mental status changes, hypertension constipation, vomiting, red to brown urine, and less commonly seizures. Acute attacks may be precipitated by medications, pregnancy, puberty, and fasting. Treatment includes glucose infusion and heme arginate. The mechanism of hyponatremia is unknown, but some patients may have a component of SIADH and will respond to fluid restriction.
Acute intermittent porphyria should be in the differential diagnosis for patients presenting with episodic hypertension and hyponatremia. Hospitalists should be familiar with the diagnosis, as these patients are likely to be seen in the inpatient setting. In addition, home medications should always be reviewed to look for potential adverse effects and interactions.
S. Wu, none; P. Malouf, none.