Subacute Thyroiditis And Related Disorders

1. Subacute ThyroiditisAnd Related Disorders Richard M. Jordan, MD, Regional Dean, School of Medicine Texas Tech Health Sciences Center at Amarillo

2. Dr. Smith’s Backyard

3. Subacute Thyroiditis And Related DisordersDefinitions • Subacute Thyroiditis – (DeQuervain’s Thyroiditis, Granulomatous Thyroiditis, Giant Cell Thyroiditis) A Post Viral Syndrome with Thyroid Pain. • Painless Thyroiditis – (Subacute Lymphocytic Thyroiditis, Silent Thyroiditis) Probable Variant of Autoimmune (Hashimoto’s) Thyroiditis. Excludes Women with Painless Thyroiditis Occurring within 1 Year of Delivery. • Postpartum Thyroiditis – Probable Variant of Autoimmune Thyroiditis, Similar to Painless Thyroiditis But Occurring Postpartum. • Drug Induced Thyroiditis – Amiodarone, Lithium, Interleukin-2, DenileukinDiffitoxin. • Radiation Induced – Occurs Post Radioactive Iodine Treatment.

4. Subacute Thyroiditis • Preceding Viral Infection with Sore Throat, Fever, Myalgias • May occur in Clusters • Damage to the Thyroid Follicles with Release of Thyroid Hormone • Goiter with Neck Pain – Can Radiate to Jaw or Ear • Elevated Sedimentation Rate, Elevated Thyroglubulin • Triphasic Course – Hyperthyroidism to Hypothyroidism to Euthyroidism • Permanent Hypothyroidism may develop in 10-15%

5. Normal Histology of the Thyroid

6. Subacute Thyroiditis(DeQuervain’s, Granulomatuous Acute viral infection Presents with viral prodrome, thyroid tenderness, and hyperthyroid symptoms Pathology Disruption and Collapse of the Thyroid Follicles Infiltration with Inflammatory Cells Neutrophils Lymphocytes Histiocytes Multinucleated “Giant” Cells

8. Subacute Thyroiditis • Suppressed Radioactive Iodine Update in Hyperthyroid Phase • Sedimentation Rate approximately 50 mm/h • Treatment – NSAIDS or Steroids, Beta Blocker in Hyperthyroid Phase

9. Painless Thyroiditis • Probable Variant of Autoimmune (Hashimoto’s) Thyroiditis • Sedimentation Rate is Normal or Slightly Elevated • May have Elevated Antithyroid Peroxidase (TPO) Levels • Thyroglobulin Levels Are Elevated • Pathology-Lymphocytic Infiltration which Persists in Recovery • Clinical Course-Similar to Subacute Thyroiditis; Hyperthyroidism (Usually Mild) Followed by Recovery or Hypothyroidism • Permanent Hypothyroidism Develops in 20-50%

12. Treatment of Painless Thyroiditis • Hyperthyroidism-Mild may require no therapy. If Symptomatic give beta-bockers • Hypothyroidism-If Symptomatic or TSH>10mU/L give thyroid hormone replacement • Monitor for the development of hypothyroidism

13. Painless Thyroiditis vs Factitious Thyrotoxicosis Painless Thyroiditis Factitious Thyrotoxicosis Goiter Small Usually Absent Thyroglobulin Elevated Undetectable Occupation Not Specific Access to Thyroid Hormone

14. Post Partum Thyroiditis • Variant of Autoimmune (Hashimoto’s) Thyroiditis • Follows Delivery • Autoimmune Damage to the Follicles with Release of Thyroid Hormone • Painless with Small Goiter • Variable Triphasic Course • Suppressed Radio Iodine Uptake • Sedimentation Rate-<30 mm/h

15. Postpartum Thyroiditis • Prevalence 7 to 10 Percent of All Pregnancies Most Common Variety of Hyperthyroidism Associated with Pregnancy • Risk Factors Elevated TPO Antibodies – 50% Will Develop Postpartum Thyroiditis Type I Diabetes Mellitus – 25% Will Develop Postpartum Thyroiditis Postpartum Thyroiditis with Prior Pregnancy • Pathology Lymphocytic Infiltration, Disruption of Follicles, Germinal Centers Variant of Hashimoto’s Thyroiditis

18. Postpartum Thyroiditis • Course 25% - Classic Triphasic Response 35% - Only Hyperthyroidism 40% - Only Hypothyroidism • Persistent Hypothyroidism After 4 years 25 to 50% have hypothyroidism or Goiter or Both 56% with a Hypothyroid Phase Develop Permanent Hypothyroidism • Patients with Postpartum Hypothyroidism Require Yearly Screening

19. Postpartum Thyroiditis Versus Graves’ Disease PostpartumGraves’ Disease Goiter Small, No Bruit Small to Large, Bruit Present Course Mild, Short Duration Mild to Severe, Long Duration Opthalmopathy Absent May Be Present Iodine Uptake Low Normal to Elevated TSI Absent Present * TSI-Thyroid Stimulating Immunoglobulin

20. Postpartum Thyroiditis Treatment • Hyperthyroid Phase – Beta Blocker • Hypothyroid Phase – Thyroid Hormone • Selenium During Pregnancy in TPO Positive Patients

21. Amiodarone and Thyroid Function Hypothyroidism-Iodine Induced Overt Hypothyroidism – 5% Subclinical Hypothyroidism – 25% Hyperthyroidism – 3-5% Type 1- (Jod-Basedow, Iodine-Induced), Underlying MNG, Graves’ Disease Type 2 – Chemical Destructive Thyroiditis

22. Distinguishing Type 1 from Type 2 Hyperthyroidism • I123 Uptake is Usually Suppressed in Both Types • Of the I123Detectable Type 1 is Likely • Presence of the Diffuse Goiter, MNG or TSI suggests Type 1 • Color Flow Doppler • Increased Flow (increased vascularity) – Type 1 • Decreased Flow (absent vascularity) – Type 2 • Interpretation Difficult

23. Treatment of Amiodarone-Induced Hyperthyroidism • Type 1 Thionamides (Methimazole or PTU) Radioactive Iodine (If I123 Uptake is Detectable) Thyroidectomy (Failure of Other Options) • Type 2 Prednisone 40 mg daily for 6 to 12 weeks Uncertain If Type 1 or Type 2 (Usually the Case) Start Prednisone 40 mg and Methimazole 40 Mg daily Measure Thyroid Function in 6 weeks If Improved Taper Methimazole If Unimproved Taper Prednisone

24. Treatment of Amiodarone-Induced Hyperthyroidism • Type 1 Thionamides (Methimazole or PTU) Radioactive Iodine (If I123 Uptake is Detectable) Thyroidectomy (Failure of other options) • Type 2 Prednisone 40 mg daily for 6 to 12 weeks • Uncertain if Type 1 or Type 2 (Usually the Case) Start Prednisone 40 mg and Methimazole 40 Mg daily • Measure Thyroid Function in 6 weeks • If Improved Taper Methimazole • If Unimproved Taper Prednisone

25. Etiology of Chemical or Destructive Thyroiditis • Interferon Alfa-10% Hypothyroidism, Painless Thyroiditis, or Graves Disease • Interleukin 2% Painless Thyroiditis • Lithium-Painless Thyroiditis But Hypothyroidism more common • DenileukinDifitox