Porphyrias: Acute Manifestations
Porphyrias often present with severe and potentially life-threatening manifestations that require prompt diagnosis and treatment. These disorders may be encountered by physicians in any specialty. Most notable in terms of emergent presentations are the ne
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Porphyrias: Acute Manifestations Karl E. Anderson
Précis 1. Clinical setting: An acute illness characterized by abdominal pain, mental symptoms and lower motor neuronal paresis and paralysis that can progress to respiratory and bulbar paralysis. 2. Diagnosis: (a) History: A family history is uncommon. Although three of the four porphyrias that lead to the acute porphyric syndrome are autosomal dominant, penetrance is so variable that it confounds the simple pedigree. The “acute porphyrias” are more common in women and rare in prepubertal individuals. Mental abnormalities include insomnia, anxiety, agitation, depression, disorientation and, hallucinations and delusions. The abdominal pain can be constant or colicky in nature, often associated with ileus. The pain can be accompanied by nausea, vomiting, and constipation or diarrhea. The primary neurological abnormality is a peripheral motor neuropathy. Weakness occurs more frequently in the upper extremities, can be asymmetrical, and can progress to respiratory paralysis or bulbar palsy. Cranial nerve defects may occur. Sudden death can occur and is usually attributed to a cardiac arrhythmia. (b) Physical examination: Tachycardia and hypertension are common. A mental status examination may reveal confusion, delirium, and disorientation. Examination of the abdomen will not reveal a cause for the steady, sometimes colicky, abdominal pain. Bowel sounds can vary from absent to high
K.E. Anderson, M.D. (*) Preventive Medicine and Community Health, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, USA e-mail: [email protected]
L. Loriaux (ed.), Endocrine Emergencies: Recognition and Treatment, Contemporary Endocrinology 74, DOI 10.1007/978-1-62703-697-9_20, © Springer Science+Business Media New York 2014
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pitched and continuous. Neurological examination will reveal findings comparable with a peripheral motor neuropathy: selective weakness, areflexia in advanced cases, fasciculations, and flaccidity. (c) Laboratory studies: These patients often have hyponatremia and abnormal liver function tests. A key laboratory finding, however, is a marked increase in urinary porphobilinogen (PBG). This abnormality is present in the three most common acute porphyrias. Demonstration of a substantial elevation in urinary PBG establishes the diagnosis of acute porphyria and allows treatment to be started as soon as possible. This measurement can be made with a rapid screening test using random spot urine. An excretion rate of greater than 6 mg/day ensures the diagnosis of acute porphyria. (d) Treatment: The treatment for an acute porphyric crisis is Hemin (lyophilized hematin) 3–4 mg/kg body weight, as an intravenous infusion once a day for 4 days. Carbohydrate loading can be used for less severe attacks, usually in a patient with a known history of acute porphyria. The usual approach is an intravenous infusion of 300 g of glucose daily in the form of D-10, 3 L a day. This treatment is contraindicated in patients with hyponatremia due
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