A 24-year-old man is brought to the emergency department by his wife due to bizarre behavior. She noticed a change in his behavior shortly after he started a fasting diet 4-5 days ago. He has become irritable and moody and has been snapping at his wife and children. The patient says that he is being haunted by large, shadowy figures that "come from another world and are trying to take me with them." He has anxiety, is sleeping less than usual, and has stopped going to work. The patient also has abdominal pain, constipation, and a tingling sensation in his fingertips. Medical history includes major depression and gastroesophageal reflux disease. His father also suffered from unexplained psychiatric episodes. The patient does not use tobacco, alcohol, or illicit drugs. His medications include omeprazole and acetaminophen. Temperature is 36.7 C (98.1 F), blood pressure is 140/80 mm Hg, pulse is 110/min, and respirations are 16/min. The abdomen is soft, bowel sounds are decreased, and there is no rebound tenderness or rigidity. Neurologic examination is within normal limits except for decreased sensation in the fingertips and mild weakness in the right arm. Which of the following is the most likely diagnosis in this patient?

Question

A 24-year-old man is brought to the emergency department by his wife due to bizarre behavior.  She noticed a change in his behavior shortly after he started a fasting diet 4-5 days ago.  He has become irritable and moody and has been snapping at his wife and children.  The patient says that he is being haunted by large, shadowy figures that "come from another world and are trying to take me with them."  He has anxiety, is sleeping less than usual, and has stopped going to work.  The patient also has abdominal pain, constipation, and a tingling sensation in his fingertips.  Medical history includes major depression and gastroesophageal reflux disease.  His father also suffered from unexplained psychiatric episodes.  The patient does not use tobacco, alcohol, or illicit drugs.  His medications include omeprazole and acetaminophen.  Temperature is 36.7 C (98.1 F), blood pressure is 140/80 mm Hg, pulse is 110/min, and respirations are 16/min.  The abdomen is soft, bowel sounds are decreased, and there is no rebound tenderness or rigidity.  Neurologic examination is within normal limits except for decreased sensation in the fingertips and mild weakness in the right arm.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

Acute intermittent porphyria (AIP), an autosomal dominant disorder involving alterations in enzymes involved in heme biosynthesis, is characterized by acute, intermittent neurovisceral attacks. New onset of psychiatric and neurologic abnormalities following a period of fasting, accompanied by unexplained, acute abdominal pain and a family history of similar episodic symptoms, is strongly suggestive of AIP. Elevated urinary porphobilinogen levels during an attack are diagnostic. The mechanism by which AIP affects the nervous system is not fully understood but is likely related to differences in expression of the altered enzymes; common precipitants of attacks include fasting (carbohydrate restriction induces enzyme synthesis), certain medications (eg, carbamazepine, phenytoin, rifampin), tobacco, and alcohol. Abdominal pain, the most common symptom in AIP, is neuropathic; therefore, abdominal tenderness in response to direct palpation is frequently absent on physical examination. Other clinical manifestations include vomiting, constipation, sensory and motor neuropathies (eg, decreased sensation in fingertips), and tachycardia. Psychiatric symptoms may be nonspecific and include anxiety, insomnia, restlessness, mood fluctuations, and psychotic symptoms (eg, hallucinations, delusions). Acute symptoms may last for days to weeks and usually resolve between attacks. The age of onset is typically in the 20s or 30s. (Choice B) Early findings in Lyme disease include erythema migrans, nonspecific systemic symptoms, and carditis, with arthritic symptoms occurring later. Common neurologic manifestations of Lyme disease include radiculopathies, meningitis, and cranial neuropathies (eg, facial palsy). Abdominal pain and psychosis are rare. (Choice C) Although this patient has a history of major depressive disorder, diagnosis of a recurrent major depressive episode requires a 2-week duration and cannot be made when a patient's presentation is better explained by a medical illness (as in this patient with classic symptoms of AIP). (Choice D) Schizophrenia is characterized by psychotic symptoms that have persisted for at least 6 months and are not better explained by a medical condition. (Choice E) Wilson disease leads to copper accumulation in tissues, causing insidious onset of hepatic, psychiatric, and neurologic dysfunction. Abdominal pain in Wilson disease is generally due to acute hepatitis or liver failure (eg, jaundice, right upper quadrant pain). Neurologic findings typically affect movement (eg, dysarthria, dystonia, tremor, parkinsonism) and are almost always accompanied by corneal copper deposits (Kayser-Fleischer rings). None of these findings are seen in this patient, in whom acute symptom onset following a period of fasting suggests AIP. Educational objective: Acute intermittent porphyria should be suspected in patients with sudden-onset abdominal pain, neuropsychiatric symptoms (eg, neuropathies, anxiety, mood changes, psychosis), and a family history of similar episodes. Elevated urine porphobilinogen during an attack is diagnostic. References: Neurological manifestations of acute intermittent porphyria. (http://www.ncbi.nlm.nih.gov/pubmed/19268005) Acute porphyrias in the USA: features of 108 subjects from porphyrias consortium. (http://www.ncbi.nlm.nih.gov/pubmed/25016127)

A 24-Year-Old Man Is Brought to the Emergency Department by His