{"id":3174,"date":"2010-05-30T22:30:05","date_gmt":"2010-05-31T02:30:05","guid":{"rendered":"http:\/\/insidesurgery.com\/?p=3174"},"modified":"2010-05-30T22:59:20","modified_gmt":"2010-05-31T02:59:20","slug":"homocystinuria","status":"publish","type":"post","link":"https:\/\/insidesurgery.com\/2010\/05\/homocystinuria\/","title":{"rendered":"Homocystinuria"},"content":{"rendered":"
Pathophysiology<\/strong><\/p>\n 1)<\/strong> group of seven different disorders 2)<\/strong> most common variant is caused by deficiency in cystathionine-beta-synthase 3)<\/strong> thought to involve abnormal cross-linking of collagen, fibrillin, and macromolecules<\/p>\n Signs and Symptoms<\/strong><\/p>\n 1)<\/strong> mental retardation\/psychiatric problems 2)<\/strong> tall stature 3)<\/strong> skeletal defects (osteoporosis) 4)<\/strong> retinal detachment 5)<\/strong> increased thromboses 6)<\/strong> lens dislocation (downward and medially) 7)<\/strong> severe atherosclerosis<\/p>\n Characteristic Test Findings<\/strong><\/p>\n Laboratory<\/em> – 1)<\/strong> increased serum homocystine 2)<\/strong> increased urine homocytine 3)<\/strong> increased serum methionine in some variants 4)<\/strong> positive cyanide-nitroprusside test<\/p>\n Associated Conditions<\/strong><\/p>\n 1)<\/strong> myocardial infarction 2)<\/strong> pulmonary embolus 3)<\/strong> cerebral vascular accidents 4)<\/strong> deep venous thrombosis 5)<\/strong> peripheral artery disease 6)<\/strong> vision loss and glaucoma<\/p>\n Biochemistry<\/strong><\/p>\n second most common variant has defect in methionine synthase<\/p>\n Treatment<\/strong><\/p>\n 1)<\/strong> early pyridoxine (induces cystathionine beta synthase activity) to blunt development of sequelae 2)<\/strong> low protein diet to methionine intake 3)<\/strong> maintenance of physiologic levels of cofactors folate, vitamin B6, and vitamin B12<\/p>\n Tips for USMLE<\/strong><\/p>\n 1)<\/strong> clinical features can be confused with Marfan’s disease 2)<\/strong> best way to differentiate is the mental retardation that occurs in homocystinuria but not Marfan’s 3)<\/strong> the lens subluxation in Marfan’s is upward and outward; in homocystinuria, it is downward and inward<\/p>\n","protected":false},"excerpt":{"rendered":" Pathophysiology 1) group of seven different disorders 2) most common variant is caused by deficiency in cystathionine-beta-synthase 3) thought to involve abnormal cross-linking of collagen, fibrillin, and macromolecules Signs and Symptoms 1) mental retardation\/psychiatric problems 2) tall stature 3) skeletal defects (osteoporosis) 4) retinal detachment 5) increased thromboses 6) lens dislocation (downward and medially) 7) […]<\/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":[63],"tags":[1652,1653,1655,1654,1656,1657],"yoast_head":"\n