{"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<p><\/p>\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 PATHOPHYSIOLOGY OF TOXIC ADENOMA AND TOXIC MULTINODULAR GOITER Typical Patient Profile Cardiac Manifestations Pathologic Findings<\/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","post-wrapper","thrv_wrapper"],"_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}]}}