{"id":5577,"date":"2021-05-20T12:06:16","date_gmt":"2021-05-20T10:06:16","guid":{"rendered":"https:\/\/meddists.com\/learn\/clinical\/hematology\/hemolytic-uremic-syndrome-hus\/"},"modified":"2021-05-20T16:14:49","modified_gmt":"2021-05-20T14:14:49","slug":"hemolytic-uremic-syndrome-hus-and-thrombotic-thrombocytopenia-purpura-ttp","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/clinical\/internal-medicine\/hematology\/thrombocytopenia-and-platelet-disorders\/hemolytic-uremic-syndrome-hus-and-thrombotic-thrombocytopenia-purpura-ttp\/","title":{"rendered":"Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP)"},"content":{"rendered":"<span class=\"block-heading\" id=\"header_1\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Background<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_1\">\n\n\n<p class=\"wp-block-paragraph\">Both HUS and TTP involve acute episodes of non-immunological destruction of platelets due to the deposition of loose strands of platelets and fibrin in small vessels and thrombosis, leading to RBC and platelet destruction, a condition known as thrombotic microangiopathy (TMA).<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>They present with similar blood profile and histological changes, <strong>microangiopathic anemia<\/strong> with<strong> red blood cell fragmentation<\/strong>, <strong>thrombocytopenia,<\/strong> and <strong>acute kidney injury<\/strong>.<\/li><li>Although there&#8217;s much overlap between the two, they are treated as distinct entities.<ul><li>TPP is caused by a deficient enzyme, while HUS is caused by shigatoxin and defective regulation of the alternative complement pathway.<\/li><li>Fibrin predominates in HUS while platelets are more prominent in TTP.<\/li><li>Neurological manifestations and multiorgan damage are more common in TTP.<\/li><\/ul><\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_2\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Hemolytic uremic syndrome<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_2\">\n\n\n<p class=\"wp-block-paragraph\">There are several variants of hemolytic uremic syndrome (HUS), with the two most significant being the <strong>typical, diarrhea-associated HUS<\/strong> and the <strong>atypical HUS<\/strong>.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_3\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Pathomechanism<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_3\">\n\n\n<ul class=\"wp-block-list\"><li>Typical, diarrhea-associated HUS is triggered by the presence of <strong>shigatoxin<\/strong> (and shiga-like toxin) produced by STEC\/EHEC O157 or Shigella bacteria.<\/li><li>Atypical HUS is typically caused complement mutations + trigger leading to defective regulation of the alternative complement pathway.<ul><li>The trigger can be certain drugs, infections (S. pneumonia, Mycoplasma), prengnacy, or systemic illnesses<\/li><\/ul><\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_4\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Clinical manifestation<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_4\">\n\n\n<ul class=\"wp-block-list\"><li>Thrombocytopenia (spontaneous bleeding, skin and mucosal purpura)<\/li><li>Microangiopathic hemolytic anemia<\/li><li>Neurological manifestation in 25% of patients (headache, confusion, stroke, seizures, coma)<\/li><li>Renal failure (AKI)<\/li><li>In typical cases, bloody diarrhea.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_5\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Diagnosis<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_5\">\n\n\n<ul class=\"wp-block-list\" id=\"block-192852a6-4f85-403f-8402-2480a2ef46d5\"><li><strong>CBC <\/strong>(severe thrombocytopenia and anemia; elevated reticulocyte count; decreased hemoglobin)<\/li><li><strong>Direct antiglobulin test<\/strong> (negative)<\/li><li><strong>Chemistry <\/strong>(elevation of LDH and unconjugated bilirubin, absent haptoglobin)<\/li><li><strong>Blood smear<\/strong> (appearance of schistocytes &#8211;&nbsp;RBC fragments)<\/li><li><strong>Coagulation tests<\/strong> (normal)<\/li><li><strong>ADAMTS13 levels<\/strong> (normal)<\/li><li><strong>Stool testing<\/strong> (demonstrating shigatoxin or STEC)<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_6\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Treatment<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_6\">\n\n\n<ul class=\"wp-block-list\"><li>For typical cases, supportive care including fluid replacement, hemodialysis<\/li><li>For atypical HUS, anti-C5 mAb (eculizumab or ravulizumab)<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_7\">\n<h3 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title1\">Thrombotic thrombocytopenic purpura<\/h3>\n<\/span><span class=\"block-content\" id=\"contents_7\">\n\n\n<p class=\"wp-block-paragraph\">Thrombotic thrombocytopenic purpura (TPP) is caused by congenital or acquired deficient activity of the plasma enzyme <strong>ADAMTS13<\/strong>.<\/p>\n\n\n<\/span><span class=\"block-heading\" id=\"header_8\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Pathophysiology<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_8\">\n\n\n<ul class=\"wp-block-list\" id=\"block-530fc8e4-c545-4cba-8296-9ccc4da32735\"><li><strong>ADAMTS13 metalloprotease<\/strong> breaks down ultra\u2010large von Willebrand factor multimers (ULVWF multimers).<\/li><li>In its absence, ULVWF multimeric&nbsp;\u2018strings\u2019 secreted from <strong>Weibel\u2013Palade bodies<\/strong> found in the endothelial cells, allowing passing platelet to adhere.<\/li><li>Passing platelets adhere through their GPIb&nbsp;receptors, leading to the formation of large platelet thrombi, which can lead to thrombotic angiopathy with ischemia or a turn into thromboembolism.<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_9\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Classification<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_9\">\n\n\n<ul class=\"wp-block-list\" id=\"block-fd197cc2-135a-4603-886a-6b72037b1193\"><li>Familial (<strong>Upshaw-Schulman syndrome<\/strong>)&nbsp;<\/li><li>Acquired<ul><li>Antibodies produced against the enzyme due to infections, autoimmune diseases, drugs, stem-cell transplantation, cardiac surgery.<\/li><li>Acquired TTP is a medical emergency.<\/li><\/ul><\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_10\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Clinical presentation<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_10\">\n\n\n<p class=\"wp-block-paragraph\">TTP has the same three features, plus multiorgan failure and the presence of fever.<\/p>\n\n\n\n<ol class=\"wp-block-list\" id=\"block-8e5eee84-9f94-4948-a8a1-57d59a3de5ee\"><li>Thrombocytopenia (spontaneous bleeding, skin and mucosal purpura)<\/li><li>Microangiopathic hemolytic anemia with thromboses and multiorgan tissue ischemia<\/li><li>Neurological manifestation is more common in TTP (headache, confusion, stroke, seizures, coma)<\/li><li>Renal failure (AKI)<\/li><li>Fever<\/li><\/ol>\n\n\n<\/span><span class=\"block-heading\" id=\"header_11\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Diagnosis<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_11\">\n\n\n<ul class=\"wp-block-list\" id=\"block-556cb2d1-6b2f-4fd8-8947-75415667c141\"><li><strong>ADAMTS13 levels<\/strong> (reduced)<\/li><li><strong>CBC <\/strong>(severe thrombocytopenia and anemia; elevated reticulocyte count)<\/li><li><strong>Direct antiglobulin test<\/strong> (negative)<\/li><li><strong>Chemistry <\/strong>(elevation of LDH and unconjugated bilirubin, absent haptoglobin)<\/li><li><strong>Blood smear<\/strong> (appearance of schistocytes &#8211;&nbsp;RBC fragments)<\/li><li><strong>Coagulation tests<\/strong> (normal)<\/li><\/ul>\n\n\n<\/span><span class=\"block-heading\" id=\"header_12\">\n<h4 class=\"wp-block-heading\" class=\"wp-block-heading\" class=\"title_collection title2\">Treatment<\/h4>\n<\/span><span class=\"block-content\" id=\"contents_12\">\n\n\n<ul class=\"wp-block-list\" id=\"block-ecbb884d-d085-4907-b651-ee057f58cfe7\"><li>Supportive:<ul><li>Plasma exchange with fresh frozen plasma&nbsp;and cryosupernatant plasma<\/li><li>Anti-vWF mAb (caplacizumab) is given in some cases<\/li><\/ul><\/li><li>In acquired TPP:<ul><li>Rituximab<\/li><li>Corticosteroids<\/li><li>Azathioprine&nbsp;or cyclophosphamide&nbsp;<\/li><\/ul><\/li><\/ul>\n<\/span><div id=\"the_titles\" style=\"display:none;\"><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Background<\/h3><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Hemolytic uremic syndrome<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Pathomechanism<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Clinical manifestation<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Diagnosis<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Treatment<\/h4><h3 class=\"wp-block-heading\" class=\"wp-block-heading\">Thrombotic thrombocytopenic purpura<\/h3><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Pathophysiology<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Classification<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Clinical presentation<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Diagnosis<\/h4><h4 class=\"wp-block-heading\" class=\"wp-block-heading\">Treatment<\/h4><\/div>","protected":false},"excerpt":{"rendered":"<p>Background Both HUS and TTP involve acute episodes of non-immunological destruction of platelets due to the deposition of loose strands of platelets and fibrin in small vessels and thrombosis, leading to RBC and platelet destruction, a condition known as thrombotic microangiopathy (TMA). They present with similar blood profile and histological changes, microangiopathic anemia with red [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":5575,"menu_order":2,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-5577","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.9 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) &#8211; Meddists<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/meddists.com\/learn\/clinical\/internal-medicine\/hematology\/thrombocytopenia-and-platelet-disorders\/hemolytic-uremic-syndrome-hus-and-thrombotic-thrombocytopenia-purpura-ttp\/\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/thrombocytopenia-and-platelet-disorders\\\/hemolytic-uremic-syndrome-hus-and-thrombotic-thrombocytopenia-purpura-ttp\\\/\",\"url\":\"https:\\\/\\\/meddists.com\\\/learn\\\/clinical\\\/internal-medicine\\\/hematology\\\/thrombocytopenia-and-platelet-disorders\\\/hemolytic-uremic-syndrome-hus-and-thrombotic-thrombocytopenia-purpura-ttp\\\/\",\"name\":\"Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) &#8211; 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