{"id":9848,"date":"2022-01-04T18:52:48","date_gmt":"2022-01-04T16:52:48","guid":{"rendered":"https:\/\/meddists.com\/learn\/clinical\/internal-medicine\/gastroenterology\/porphyrias\/"},"modified":"2022-01-04T19:09:26","modified_gmt":"2022-01-04T17:09:26","slug":"porphyrias","status":"publish","type":"page","link":"https:\/\/meddists.com\/learn\/clinical\/internal-medicine\/metabolism\/porphyrias\/","title":{"rendered":"Porphyrias"},"content":{"rendered":"\n

Heme metabolism<\/h3>\n<\/span>\n\n\n

Heme is an iron-containing pigment mostly produced in the bone marrow and where it is incorporated into hemoglobin of RBCs and CYP450 enzymes of hepatocytes. <\/p>\n\n\n\n

Heme synthesis requires 8 enzymes<\/strong> that produce and modify molecules known as porphyrins.<\/p>\n\n\n\n

  • The first enzyme is ALA synthase<\/strong>, the rate-limiting step; its deficiency<\/strong> leads to sideroblastic anemia (iron accumulation in mitochondria)<\/li>
  • Heme is a negative regulator of ALA synthase; a decrease in heme quantity will increase its activity, and will cause the accumulation of precursors (porphyrins) proximal to the location of the defective enzyme.<\/li><\/ul>\n\n\n<\/span>\n

    Porphyrias<\/h3>\n<\/span>\n\n\n

    Porphyrias are metabolic disorders in which hemoglobin is abnormally metabolized leading to the accumulation of heme precursors (porphyrins) in tissues, causing toxicity. <\/p>\n\n\n\n

    • Porphyrias occur due to enzyme deficiency of any of the last 7 enzymes in the production of heme, leading to the accumulation of porphyrins. It that can be genetic or acquired.<\/li>
    • Classified as acute (neurovesical) <\/strong>or cutanous<\/strong> based on their clinical manifestation, and as hepatic <\/strong>or erythropoietic <\/strong>depending on the site of overproduction and accumulation.<\/li>
    • All porphyrias are inherited (mostly AD), except for porphyria cutanea tarda <\/strong>(PCT) which is acquired.<\/li>
    • Acute<\/strong> (neurovesical<\/strong>) porphyrias <\/strong>present with neurological and mental disorders (psychosis, peripheral neuropathy, dementia), and abdominal pain. They are triggered by events that enhance ALA synthase activity, such as alcohol, certain drugs, emotional stress, and changes in the menstrual cycle.
      • Common types include acute intermittent<\/li><\/ul>
        • Treatment <\/strong>includes avoid the triggers, glucose, IV heme, analgesics (narcotic)<\/li><\/ul><\/li>
        • Cutanous porphyrias<\/strong> present with symptoms that involve the skin, and are triggered by UV exposure. It occurs as porphyrins accumulate in the skin, and they oxidize as they are exposed to UV.
          • Common types include porphyria cutanea tarda, and erythropoietic protoporphyria<\/li><\/ul>
            • Presents with photosensitivity, blistering, and scarring; chronic liver disorders are common in cutanous porphyrias.<\/li><\/ul>
              • Treatment<\/strong> includes sun avoidance, sunscreen, and blood donation<\/li><\/ul><\/li>
              • Diagnosis<\/strong>
                • Blood and urine testing, screening for porphyrin and its precursors<\/li><\/ul>
                  • Genetic analysis<\/li><\/ul><\/li><\/ul>\n<\/span>

                    Heme metabolism<\/h3>

                    Porphyrias<\/h3><\/div>","protected":false},"excerpt":{"rendered":"

                    Heme metabolism Heme is an iron-containing pigment mostly produced in the bone marrow and where it is incorporated into hemoglobin of RBCs and CYP450 enzymes of hepatocytes. Heme synthesis requires 8 enzymes that produce and modify molecules known as porphyrins. The first enzyme is ALA synthase, the rate-limiting step; its deficiency leads to sideroblastic anemia […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":9852,"menu_order":1,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-9848","page","type-page","status-publish","hentry"],"yoast_head":"\nPorphyrias – 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\/metabolism\/porphyrias\/\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" 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