Hyperthyroidism

Treat severe thyrotoxicosis with rapid clinical deterioration as suspected thyroid storm. Initiate cardiovascular stabilization, respiratory support as needed, temperature control, and evaluation and treatment of precipitating factors while beginning thyroid-directed therapy. PubMedPubMedApproach to the patient with thyroid storm

After initial supportive measures, start propranolol 40-80 mg orally every 4-6 hours in suspected thyroid storm unless beta-blockade is clinically unsuitable. Give PTU 500-1,000 mg as a loading dose followed by 250 mg every 4 hours, or methimazole 20 mg every 4-6 hours; PTU additionally inhibits peripheral T4-to-T3 conversion. PubMedPubMedThyroid Storm - StatPearls - NCBI Bookshelf - NIH

Administer iodine only after thionamide therapy: give supersaturated potassium iodide 5 drops orally every 6 hours beginning 1 hour after PTU or methimazole. This sequence avoids providing substrate for new thyroid hormone synthesis before synthesis blockade. PubMedPubMedThyroid Storm - StatPearls - NCBI Bookshelf - NIH

Obtain serum TSH and free T4 (or free T4 index) when hyperthyroidism is suspected. A low TSH with elevated free T4 or free T4 index is the biochemical pattern of hyperthyroidism. TSH is typically less than 0.1 mU/L in overt primary hyperthyroidism and is often less than 0.02 mU/L. ScienceDirect+1ScienceDirectThyroid Function Test - an overviewthyroidThyroid Function Tests

If TSH is suppressed but free T4 is normal, obtain total T3 or free T3 to detect isolated T3 thyrotoxicosis. Elevated T3 with normal free T4 represents active overt disease; normal free T4 and T3 with low TSH represents subclinical hyperthyroidism. Free T3 measurement may be less reliable than total T3. ScienceDirect+2ScienceDirectEuthyroidism - an overview | ScienceDirect TopicsthyroidThyroid Function TeststhyroidThyroid Health Blog: Hyperthyroidism Awareness | American Thyroid Association

A low TSH is not always primary thyroid hormone excess. Low or normal TSH together with low free T4 indicates central hypothyroidism rather than hyperthyroidism. During the first trimester, hCG-mediated stimulation can lower TSH; assess overt disease with free T4 or pregnancy-specific total T4 reference ranges. ScienceDirect+1ScienceDirectThyroid Peroxidase Antibody - an overviewthyroidThyroid Function Tests

Increased radioiodine uptake identifies endogenous hormone overproduction and most often reflects Graves disease, toxic multinodular goiter, or toxic adenoma. Graves disease is the most common cause of hyperthyroidism, followed by toxic nodular goiter; thyroiditis is an important alternative cause of thyrotoxicosis. The Lancet+1The LancetHyperthyroidismAnnals of Internal MedicineHyperthyroidism | Annals of Internal Medicine

Order TSH-receptor antibodies or thyroid-stimulating immunoglobulin when Graves disease is suspected or radionuclide imaging is unsuitable. Positive TRAb or TSI supports Graves disease; exophthalmos or extraocular muscle involvement further supports Graves orbitopathy. A thyroid uptake scan, TRAb/TSI measurement, and ultrasound are complementary tools for separating Graves disease, toxic multinodular goiter, and toxic adenoma. ScienceDirect+2ScienceDirectThyroid Peroxidase Antibody - an overviewthyroidThyroid Health Blog: Hyperthyroidism Awareness | American Thyroid AssociationthyroidPediatric Thyroid Function Tests | American Thyroid Association

Use radionuclide uptake/scan to distinguish hormone production from transient thyroiditis or factitious thyrotoxicosis when the clinical diagnosis is uncertain. Low uptake with absent goiter and low thyroglobulin favors exogenous thyroid hormone use. In contrast, high uptake points to Graves disease, toxic multinodular goiter, or toxic adenoma. Annals of Internal Medicine+2Annals of Internal MedicineHyperthyroidism | Annals of Internal MedicineScienceDirectEuthyroidism - an overview | ScienceDirect TopicsScienceDirectThyroid Stimulating Immunoglobulin - an overview

Avoid radioactive iodine diagnostic studies in pregnancy. In pregnancy, breastfeeding, or persons trying to conceive, thyroid ultrasound with Doppler blood flow can help distinguish Graves disease from thyroiditis; TRAb or TSI provides an additional non-radiation test. Measure TSI or TRAb at 20-24 weeks' gestation when Graves disease is present to determine the need for increased fetal monitoring. ScienceDirect+1ScienceDirectThyroid Peroxidase Antibody - an overviewWHODiagnosis and Management of Thyrotoxicosis

For symptomatic relief of adrenergic manifestations while definitive biochemical control is pending, use a beta-blocker such as propranolol or atenolol. These agents reduce palpitations, tachycardia, tremor, anxiety, heat intolerance, fatigability, and dyspnea but do not suppress thyroid hormone synthesis. cdn clinicaltrialscdn clinicaltrialsA multi-center, open label, randomised, parallel-group study to

For Graves disease, methimazole is the usual preferred thionamide outside pregnancy. A cited Graves regimen is methimazole 10-20 mg orally once daily until TSH normalizes; maintenance dosing is 5-15 mg/day. Antithyroid drugs inhibit thyroid peroxidase-dependent hormone synthesis. PubMed+1PubMedManagement of thyrotoxicosis: anti thyroid drugs - NCBI BookshelfPubMedMethimazole - StatPearls - NCBI Bookshelf

Counsel every patient receiving methimazole or PTU about serious toxicity. Agranulocytosis occurs in approximately 0.2%-0.5% of patients receiving thionamides. PTU is associated with hepatotoxicity and vasculitis, while methimazole/carbimazole is associated with teratogenicity and pancreatitis. PubMed+1PubMedAcute and emergency care for thyrotoxicosis and thyroid storm - PMCPubMedManagement of thyrotoxicosis: anti thyroid drugs - NCBI Bookshelf

Reserve PTU primarily for the first trimester of pregnancy or when methimazole cannot be tolerated; the FDA boxed warning describes severe and sometimes fatal liver injury with PTU. Switch to methimazole in the second and third trimesters. PubMedPubMedAcute and emergency care for thyrotoxicosis and thyroid storm - PMC

Radioiodine therapy is an established definitive treatment for hyperthyroidism that reduces thyroid hormone synthesis through targeted beta radiation. It commonly results in permanent hypothyroidism; adverse effects include transient thyroiditis, sialadenitis, xerostomia, and rare secondary malignancy. WHO+1WHODiagnosis and Management of ThyrotoxicosisPubMedRadioactive Iodine (I-131) Therapy for Hyperthyroidism and Thyroid Cancer - StatPearls - NCBI Bookshelf

Anticipate a transient rise in circulating thyroid hormone after I-131 from damaged follicles releasing preformed T3 and T4. In severe hyperthyroidism or significant cardiac disease, use selective methimazole pretreatment, then stop methimazole 3-5 days before radioiodine to avoid reduced treatment efficacy. PubMedPubMedRadioactive Iodine (I-131) Therapy for Hyperthyroidism and Thyroid Cancer - StatPearls - NCBI Bookshelf

Consider orbitopathy when selecting radioiodine for Graves disease. Graves ophthalmopathy may occur or worsen after radioiodine, particularly in smokers and in patients with severe hyperthyroidism. WHOWHODiagnosis and Management of Thyrotoxicosis

Thyroidectomy is a definitive alternative when medical therapy is contraindicated or unsuccessful, including severe liver disease or leukopenia precluding thionamides, and can be used after stabilization as a bridge-to-definitive option in refractory severe disease. Patients with thyroid storm should generally be medically controlled before surgery. PubMed+1PubMedClinical Review and Update on the Management of Thyroid StormPubMedApproach to the patient with thyroid storm