{"id":4422352,"date":"2025-01-11T14:41:03","date_gmt":"2025-01-11T20:41:03","guid":{"rendered":"https:\/\/myendoconsult.com\/learn\/topics\/toxic-thyroid-nodules\/"},"modified":"2025-01-13T06:04:41","modified_gmt":"2025-01-13T12:04:41","slug":"toxic-thyroid-nodules","status":"publish","type":"oen_topic","link":"https:\/\/myendoconsult.com\/learn\/topics\/toxic-thyroid-nodules\/","title":{"rendered":"Toxic Thyroid Nodules"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">CLINICAL MANIFESTATIONS OF TOXIC ADENOMA AND TOXIC MULTINODULAR GOITER<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Overview and Pathophysiology<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Definition<\/strong>\n<ul class=\"wp-block-list\">\n<li>Hyperthyroidism caused by <strong>hyperfunctioning thyroid adenoma(s)<\/strong> independent of TSH (thyrotropin) regulation.<\/li>\n\n\n\n<li>Second most common cause of hyperthyroidism after <a href=\"https:\/\/myendoconsult.com\/learn\/topics\/graves-disease\/\"  data-wpil-monitor-id=\"115\">Graves disease<\/a>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Somatic Mutations<\/strong>\n<ul class=\"wp-block-list\">\n<li>Often related to <strong>activating mutations<\/strong> in the TSH receptor gene \u2192 constitutive <a href=\"https:\/\/myendoconsult.com\/learn\/thyroid-hormone-synthesis\/\"  data-wpil-monitor-id=\"120\">thyroid hormone<\/a> production.<\/li>\n\n\n\n<li><strong>Toxic Multinodular <a href=\"https:\/\/myendoconsult.com\/learn\/goiter\/\"  data-wpil-monitor-id=\"121\">Goiter<\/a><\/strong>: Multiple nodules with similar mutations in some nodules, others differ in function.<\/li>\n\n\n\n<li><strong>Toxic Adenoma<\/strong>: Typically a single, autonomously functioning <a href=\"https:\/\/myendoconsult.com\/learn\/evaluation-of-a-thyroid-nodule-an-algorithm-based-approach\/\"  data-wpil-monitor-id=\"116\">thyroid nodule<\/a>.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Clinical Features Distinct from Graves Disease<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Demographics<\/strong>\n<ul class=\"wp-block-list\">\n<li>Patients usually <strong>>40 years old<\/strong>.<\/li>\n\n\n\n<li>Often have a long-standing <strong>multinodular goiter<\/strong> or single <a href=\"https:\/\/myendoconsult.com\/learn\/thyroid-nodule-calculator\/\"  data-wpil-monitor-id=\"122\">thyroid nodule<\/a>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Cardiovascular Dominance<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Marked shortness of breath<\/strong>, tachycardia, frequently <strong>atrial fibrillation<\/strong>.<\/li>\n\n\n\n<li>Heart failure can occur, but <strong>no<\/strong> prolonged circulation time (unlike Graves).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Lack of Eye and Skin Findings<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>No ophthalmopathy<\/strong>, pretibial myxedema, or thyroid acropachy (common in Graves).<\/li>\n\n\n\n<li>Possible mild eyelid retraction or eyelid lag, but minimal if any.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Less Severe Hypermetabolic Symptoms<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Less muscle weakness<\/strong>, less weight loss, and lower nervous excitability compared to Graves.<\/li>\n\n\n\n<li>Many female patients are postmenopausal \u2192 fewer <a href=\"https:\/\/myendoconsult.com\/learn\/menstrual-cycle\/\"  data-wpil-monitor-id=\"123\">menstrual cycle<\/a> changes.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Hormone Levels<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Moderate<\/strong> elevations in serum free T4 and total T3 (not as high as Graves).<\/li>\n\n\n\n<li>Slight decrease in total and HDL cholesterol.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Radioactive Iodine Uptake and Imaging<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Toxic Adenoma (Solitary Nodule)<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>High uptake<\/strong> localized in the hyperfunctioning nodule.<\/li>\n\n\n\n<li><strong>No<\/strong> uptake in the rest of the gland (\u201csuppressed\u201d <a href=\"https:\/\/myendoconsult.com\/learn\/normal-thyroid-ultrasound-images\/\"  data-wpil-monitor-id=\"117\">normal thyroid<\/a>).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Toxic Multinodular Goiter<\/strong>\n<ul class=\"wp-block-list\">\n<li>One or more areas of <strong>focal increased uptake<\/strong> (hot nodules).<\/li>\n\n\n\n<li>Remaining gland may show multiple \u201ccold\u201d (nonfunctioning) or normal areas.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Management<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Symptomatic Control<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>\u03b2-Adrenergic blockers<\/strong> (e.g., propranolol) to manage palpitations, tremor, tachycardia.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Definitive Treatment<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Thionamides<\/strong> (e.g., methimazole, propylthiouracil) \u2192 typically used short-term in elderly or cardiac-compromised patients to achieve euthyroidism before definitive therapy.\n<ul class=\"wp-block-list\">\n<li>Unlike Graves disease, hyperthyroidism <strong>recurs<\/strong> if thionamides are withdrawn without further intervention.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Radioiodine Ablation<\/strong> \u2192 destroys hyperfunctioning nodule(s) over 2\u20134 months.\n<ul class=\"wp-block-list\">\n<li>Most patients become <strong>euthyroid<\/strong> because <a href=\"https:\/\/myendoconsult.com\/learn\/normal-thyroid-follicular-cells\/\"  data-wpil-monitor-id=\"118\">normal thyroid<\/a> tissue is suppressed and takes up little radioiodine.<\/li>\n\n\n\n<li><strong>Large<\/strong> toxic multinodular goiters may respond less to radioiodine \u2192 <strong>surgery<\/strong> is often preferred.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Surgery<\/strong>\n<ul class=\"wp-block-list\">\n<li>Especially if goiter is very large, causing compressive symptoms, or if there is suspicion of malignancy.<\/li>\n\n\n\n<li>Also for those who prefer surgical resolution or are not good candidates for radioiodine.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">PATHOPHYSIOLOGY OF TOXIC ADENOMA AND TOXIC MULTINODULAR GOITER<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Typical Patient Profile<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Often an older adult (commonly <strong>middle-aged woman<\/strong>).<\/li>\n\n\n\n<li>History of <strong>nontoxic (euthyroid) nodular goiter<\/strong> that later becomes hyperfunctional.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Cardiac Manifestations<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>High-output heart failure<\/strong>: Short circulation time with high venous pressure.<\/li>\n\n\n\n<li>Palpitations, <strong>atrial fibrillation<\/strong>, dyspnea.<\/li>\n\n\n\n<li>Fewer extrathyroidal findings compared to Graves disease (no ophthalmopathy, dermopathy, or muscle weakness typical of Graves).<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Pathologic Findings<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Single Toxic Adenoma<\/strong>\n<ul class=\"wp-block-list\">\n<li>One enlarged hyperfunctioning nodule (often red in color).<\/li>\n\n\n\n<li>Remaining gland is suppressed, smaller or nonfunctional.<\/li>\n\n\n\n<li>Very rare to hear a <strong>bruit<\/strong> or feel a <strong>thrill<\/strong>.<\/li>\n\n\n\n<li><strong>Histology<\/strong>: Uniform hyperplasia of follicular cells with minimal papillary infolding, no lymphocytic infiltration.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Multinodular Goiter<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Multiple nodules<\/strong>: Some hyperfunctioning (hot), others hypofunctioning (cold).<\/li>\n\n\n\n<li>Possibly malignant or premalignant foci in one nodule.<\/li>\n\n\n\n<li><a href=\"https:\/\/myendoconsult.com\/learn\/histology-of-hurthle-cell-adenoma-and-carcinoma\/\"  data-wpil-monitor-id=\"119\">Histology of functioning areas resembles an <strong>adenoma<\/strong><\/a> (well-differentiated hyperplasia), distinct from surrounding normal tissue.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Molecular Basis<\/strong>\n<ul class=\"wp-block-list\">\n<li><strong>Constitutive activation<\/strong> of TSH receptor in the nodule(s) from <strong>somatic point mutations<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n\n","protected":false},"excerpt":{"rendered":"<p>CLINICAL MANIFESTATIONS OF TOXIC ADENOMA AND TOXIC MULTINODULAR GOITER Overview and Pathophysiology Clinical Features Distinct from Graves Disease Radioactive Iodine Uptake and Imaging Management&hellip;<\/p>\n","protected":false},"featured_media":0,"template":"","oen_topic_chapter":[683],"class_list":["post-4422352","oen_topic","type-oen_topic","status-publish","hentry","oen_topic_chapter-thyroid-gland"],"_links":{"self":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422352","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic"}],"about":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/types\/oen_topic"}],"version-history":[{"count":3,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422352\/revisions"}],"predecessor-version":[{"id":4422356,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422352\/revisions\/4422356"}],"wp:attachment":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/media?parent=4422352"}],"wp:term":[{"taxonomy":"oen_topic_chapter","embeddable":true,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic_chapter?post=4422352"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}