8 ACOFP 55th Annual Convention & Scientific Seminars New Physicians and Residents: The Good, The Bad, The Thyroid Gland Natasha Bray, DO 3/14/2018 Natasha N. Bray, DO, MSEd, FACOI, FACP Visiting Professor of Rural Medicine – Internal Medicine Oklahoma State University College of Osteopathic Medicine ▪ Length: 5 cm ▪ Width: 2 cm ▪ Depth: 2 cm ▪ Weight 10-20 grams 1 3/14/2018 ▪ Active Thyroid Hormone ▪ Thyroxine (T4) and Triiodothyronine (T3) ▪ Iodine is critical to formation of thyroid hormone ▪ Dietary sources – seafood, dairy products, iodized salt ▪ Iodine deficiency in US is rare ▪ Regulation ▪ TSH secretion ▪ Peripheral conversion of T4 to T3 ▪ T4:T3 secretion by thyroid gland 20:1 ▪ Most T3 (80%) results from 5’-deiodination of T4 in peripheral tissue Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J. Harrison's Manual of Medicine, 18e; 2014 Available at: http://accessmedicine.mhmedical.com/content.aspx?bookid=1140&sectionid=63503819 Accessed: January 15, 2018 ▪ Thyroxine-binding globulin (TBG) ▪ Transport T3 & T4 ▪ Only free T4 and free T3 are metabolically active ▪ In the serum, 0.04% of total T4 and T3 are in free or active forms ▪ T3 has up to 10 times the potency of T4 2 3/14/2018 TSH Free T4 Hypothyroid High Low Hyperthyroid Los High 3 3/14/2018 ▪ 36-year-old female reports insomnia, weight loss and anxiety over the past 8-10 weeks. She did not get her period this month. ▪ Physical Exam ▪ Alert and oriented ▪ Vital signs are normal ▪ Thyroid gland is diffusely enlarged. No discrete nodule palpated. ▪ No exophthalmos ▪ No pretibial myxedema What lab results would you expect to find? ▪ 36-year-old female reports insomnia, A. Low TSH, low free T4, high T3 weight loss and anxiety over the past 8-10 weeks. She did not get her B. High TSH, high free T4, +TPO period this month. antibodies ▪ Physical Exam ▪ Alert and oriented C. Low TSH, high free T4, +TPO ▪ Vital signs are normal antibodies ▪ Thyroid gland is diffusely enlarged. No discrete nodule palpated. D. High TSH, high free T3, -TPO ▪ No exophthalmos antibodies ▪ No pretibial myxedema E. Low TSH, low free T4, +TPO antibodies 4 3/14/2018 What lab results would you expect to find? ▪ 36-year-old female reports insomnia, A. Low TSH, low free T4, high T3 weight loss and anxiety over the past 8-10 weeks. She did not get her B. High TSH, high free T4, +TPO period this month. antibodies ▪ Physical Exam ▪ Alert and oriented C.Low TSH, high free T4, ▪ Vital signs are normal ▪ Thyroid gland is diffusely enlarged. No +TPO antibodies discrete nodule palpated. D. ▪ No exophthalmos High TSH, high free T3, -TPO ▪ No pretibial myxedema antibodies E. Low TSH, low free T4, +TPO antibodies What is the most likely cause of her hyperthyroidism? ▪ 36-year-old female reports insomnia, A. Toxic multinodular goiter weight loss and anxiety over the past 8-10 weeks. She did not get her B. Graves’ disease period this month. C. Subacute thyroiditis ▪ Physical Exam ▪ Alert and oriented D. Iodine ingestion ▪ Vital signs are normal E. Toxic adenoma (hot nodule) ▪ Thyroid gland is diffusely enlarged. No discrete nodule palpated. ▪ No exophthalmos ▪ No pretibial myxedema 5 3/14/2018 What is the most likely cause of her hyperthyroidism? ▪ 36-year-old female reports insomnia, A. Toxic multinodular goiter weight loss and anxiety over the past 8-10 weeks. She did not get her B. period this month. Graves’ disease ▪ Physical Exam C. Subacute thyroiditis ▪ Alert and oriented D. Iodine ingestion ▪ Vital signs are normal ▪ Thyroid gland is diffusely enlarged. No E. Toxic adenoma (hot nodule) discrete nodule palpated. ▪ No exophthalmos ▪ No pretibial myxedema ▪ Decreased bone density ▪ Increased heart rate ▪ Elevated biochemical markers of bone ▪ Presence of atrial fibrillation resorption: ▪ Increased cardiac contractility ▪ Increased osteocalcin ▪ Increased urinary hydroxyproline ▪ Increased LV mass index ▪ Increased serum glucose ▪ Exophthalmos or specific ophthalmopathy ▪ Increased serum Ca and Alk Phos. ▪ Large, tender thyroid ▪ Decreased LDL and Cholesterol ▪ Restless and irritability ▪ Increased hepatic enzyme and creatine ▪ Weight loss kinase ▪ Finger tremor ▪ Increased sex hormone binding globulin ▪ Increased sweating (altered menses and fertility) 6 3/14/2018 Normal or High Radioiodine Uptake Absent (or near) Radioiodine Uptake ▪ Autoimmune Thyroid Disease ▪ Thyroiditis ▪ Graves’ Disease ▪ Subacute Granulomatous (de Quervain’s) Thyroiditis ▪ Hashitoxicosis ▪ Painless Thyroiditis (silent thyroiditis, lymphocytic ▪ Autonomous Thyroid Tissue thyroiditis) ▪ Toxic Adenoma ▪ Postpartum Thyroiditis ▪ Toxic Multinodular Goiter ▪ Amiodarone (also may cause iodine-induced hyperthyroidism) ▪ TSH-mediated Hyperthyroidism ▪ Radiation Thyroiditis ▪ TSH-producing Pituitary Adenoma ▪ Non-neoplastic TSH-mediated Hyperthyroidism ▪ Palpation Thyroiditis ▪ Mutation in nuclear triiodothyronine (T3) receptor ▪ Exogenous Thyroid Hormone Intake ▪ Mutation of TSH receptor ▪ Excessive Replacement Therapy ▪ Human Chorionic Gonadotropin-Mediated ▪ Intentional Suppressive Therapy Hyperthyroidism ▪ Hyperemesis Gravidum ▪ Factitious Hyperthyroidism ▪ Trophoblastic Disease ▪ Ectopic Hyperthyroidism ▪ Struma ovarii ▪ Metastatic follicular thyroid cancer Uptake Low High Thyroiditis Grave’s Hot Nodules 7 3/14/2018 ▪ Euthyroid hyperthyroxinemia ▪ Abnormal Thyroid hormone-binding hormone ▪ High T4, Normal-High T3, Normal TSH ▪ Low serum TSH without hyperthyroidism ▪ Central hypothyroidism (Low THS, normal FT4 & T3) ▪ Nonthyroidal illness ▪ Recovery from hyperthyroidism ▪ Pregnancy – physiologic lowering of TSH ▪ Healthy older patient – altered set point of the hypothalamic-pituitary-thyroid axis ▪ Biotin Ingestion ▪ Interference with the assay falsely low TSH and high T4 & T3 Sharma A, Baumann NA, Shah P. Biotin-Induced Biochemical Graves Disease: A Teachable Moment. JAMA Intern Med. 2017; 177(4): 571. Hyperthyroidism, goiter, ophthalmopathy (orbitopathy), & pretibial/localized myxedema ▪ Thyrotropin Receptor Simulation Antibodies (TSHR-Ab) ▪ Increase thyroid hormone synthesis, secretion, and hypertrophy of thyroid gland ▪ Treatment – ▪ Anti-thyroid medications (Methimazole or PTU) ▪ MCC of Hyperthyroidism in US ▪ First-line, may induce long-term remission. ▪ No remission achieved by 1-2 years RAI ablation or ▪ Laboratory Findings thyroidectomy may be considered ▪ Elevated T4 & T3 ▪ Beta Blockers ▪ Depressed TSH ▪ Treat symptoms ▪ Positive TSHR-Ab ▪ Propranolol inhibits peripheral conversion of ▪ May have anti-TG and anti-TPO T4 to T3 ▪ Elevated Radioiodine Uptake ▪ Exophthalmos ▪ (I-123 or Tc-99) ▪ Tapering steroid dose (6-12 weeks) ▪ Eye Surgery indicated if diplopia or loss of vision 8 3/14/2018 ▪ Autoimmune Thyroid Disease ▪ Hyperthyroid before deterioration into hypothyroid state ▪ TSH Receptor Blocker & TSH Receptor Stimulation Genes/Ab present ▪ Elderly Women ▪ Focal or diffuse hyperplasia of thyroid follicular cells ▪ Independent of TSH regulation ▪ More common in areas with low iodine intake ▪ Clinical findings: ▪ Mass effect on neighboring structures – airway ▪ Treatment obstruction and dysphagia ▪ Anti-thyroid medication (thionamide) ▪ No exophthalmos or pretibial myxedema ▪ Subtotal thyroidectomy ▪ Lab findings ▪ Radioiodine ablation ▪ Low TSH, High T4 ▪ Increased radioiodine uptake 9 3/14/2018 ▪ Inhibit production of thyroid hormones (organification of iodine to tyrosine and coupling of iodotyrosines to form T3 and T4) ▪ May also inhibit thyroid hormone secretion Principle side ▪ May have immunomodulatory activity on autoimmune disease effects Rash ▪ Methimazole Nausea ▪ Preferred due to less side effects and toxicity, longer duration of action, more rapid efficacy Hepatitis ▪ Starting dose 10-15 mg daily (larger goiter/sever symptoms 20-30 mg/day) Vasculitis ▪ Maintenance dose is 5 – 15 mg daily Agranulocytosis ▪ Duration of therapy generally 12 to 18 months, but has been used for up to 10 years safely more common ▪ Permanent remission after cessation of therapy in only 20-30% of patients with PTU ▪ Propylthiouracil (PTU) ▪ Drug of choice in pregnancy patients due to teratogenic effects of methimazole ▪ Dosage 300 – 450 mg daily initially in 2 to 3 doses ▪ Maintenance dose is 50 – 300 mg in 2 to 3 doses Radioiodine Ablation Surgery ▪ Therapy of Choice in US (69%) ▪ Indicated for: ▪ Used less in Europe (22%) & ▪ Obstructive goiter Japan (11%) ▪ Pregnant women ▪ I-131 capsule (or oral ▪ Iodine allergy solution) ▪ Refusal of radiation therapy ▪ Ablation requires 6-18 weeks for euthyroid state ▪ 20% will need second round of treatment 10 3/14/2018 ▪ A 32-year-old man is evaluated for a 1-week history of severe neck pain. He also has heat intolerance, palpitations, and insomnia. Medical history is significant only for a viral upper respiratory tract infection 3 weeks ago. He takes no medications. ▪ Physical examination ▪ Anxious, sweating ▪ T - 36.9 °C (98.6 °F), BP - 124/64 mm Hg, P - 118/min, RR - 12/min ▪ No proptosis or lid lag ▪ Heart: Regular, tachycardic, no murmur ▪ Lungs: Clear to auscultation bilaterally ▪ Thyroid gland: normal-sized, very tender to palpation. No thyroid nodules palpated. ▪ Laboratory Evaluation ▪ TSH: <0.008 µU/mL (0.008 mU/L) ▪ Free-T4: 3.2 ng/dL (41.3 pmol/L) ▪ Total T3: 310 ng/dL (4.8 nmol/L) ▪ Thyroid-stimulating immunoglobin index: <1.3 (normal, <1.3) ▪ 24-hour radioactive iodine uptake: 5% (low) ▪ A 32-year-old man is evaluated for a 1- week history of severe neck pain. He also has heat intolerance, palpitations, and insomnia. Medical history is significant only for a viral