Acute intermittent porphyria is a disease marked by an enzyme deficiency<\/p>\n
Pathophysiology of acute intermittent porphyria<\/p>\n
1) type of hepatic hemoglobinopathy (hepatic porphyria)
\n2) caused by decrease levels of HMB synthase (PBG deaminase)
\n3) classic subtype – enzyme defect occurs in erythrocytes
\n4) variant subtype – enzyme defect is in nonerythrocyte tissues
\n5) has highly variable clinical course
\n6) occurs episodically when activated by one or more precipitating factors
\n7) precipitating factors are hormones, drugs, diet, stress (e. g. infections, surgery), alcohol, low-calorie diet<\/p>\n
Signs and Symptoms<\/p>\n
1) gastrointestinal – abdominal pain, ileus, distention, nausea, vomiting, constipation, diarrhea
\n2) autonomic – sweating, hypertension, dysuria, urinary retention, black-colored urine
\n3) muscular\/skin – pain in extremities, neck and torse and hirsuitism (thought to be the disease state that gave rise to the werewolf legends
\n4) neurologic – peripheral motor neuropathy (usually affects arms and shoulders first), headache, seizures
\n5) psychiatric – anxiety, depression, paranoia, and hallucinations<\/p>\n
Characteristic Test Findings<\/p>\n
Laboratory – 1) increased ALA and PBG in both serum and urine 2) hyponatremia 3) black-colored urine EKG – 4) arrhythmias<\/p>\n
Histology\/Gross Pathology<\/p>\n
neuropathy is caused by axonal degeneration (not demyelinization)<\/p>\n
Associated Conditions<\/p>\n
partial list of drugs that precipitate attacks:<\/p>\n
barbituates
\nalcohol
\nsulfonamides
\nmeprobamate
\ncarbamazepine
\nvalproic acid
\nglutethimide
\nphenytoin
\nestrogens
\ndanazol<\/p>\n
Inheritance\/Epidemiology<\/p>\n
1) autosomal dominant
\n2) more common in Great Britain and Scandinavia<\/p>\n
Treatment<\/p>\n
1) heme infusion (hematin, heme albumin, or heme arginate
\n2) avoidance of precipitating factors
\n3) long-acting gonadotropin-release hormone analog<\/p>\n
Tips for USMLE<\/p>\n","protected":false},"excerpt":{"rendered":"
Acute intermittent porphyria is a disease marked by an enzyme deficiency Pathophysiology of acute intermittent porphyria 1) type of hepatic hemoglobinopathy (hepatic porphyria) 2) caused by decrease levels of HMB synthase (PBG deaminase) 3) classic subtype – enzyme defect occurs in erythrocytes 4) variant subtype – enzyme defect is in nonerythrocyte tissues 5) has highly […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[5156],"tags":[],"yoast_head":"\n