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Thyroid Update

Thyroid Update. Dr. D. Zatelny BaSc , MD, FRCPC. Objectives. Review practical primary care management of 3 common thyroid conditions through a case based approach Encourage discussion !. Case 1. 26 yr old married executive secretary referred for possible hypothyroidism PMHx: depression

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Thyroid Update

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  1. Thyroid Update Dr. D. Zatelny BaSc, MD, FRCPC

  2. Objectives • Review practical primary care management of 3 common thyroid conditions through a case based approach • Encourage discussion !

  3. Case 1 • 26 yr old married executive secretary referred for possible hypothyroidism • PMHx: depression • Meds: BCP • FMHx: father had MI age 52 yrs. mother had Graves disease • HPI: Patient c/o fatigue and weight gain She is concerned she may be hypothyroid

  4. Case 1 • O/E BP 112/66 HR =74 bpm BMI = 30 eye exam normal thyroid exam normal • Labs: Hb = 116 ferriten = 9 sTSH = 6.2

  5. What would you do next?

  6. Case 1 • After discussion with patient she elects to repeat her bloodwork in 3-4 months including FT4 and TAb • Patient presents 2 months later concerned she may be pregnant

  7. Case 1 • LABS: Bhcg +ve sTSH = 5.8 FT4 = 15 TPOAb =1:764 TGAb = 1:66

  8. Pregnancy & the Thyroid Pregnancy is a stress test for the thyroid

  9. Pregnancy & the Thyroid • The gland increases 10% in size • Production of FT4 & FT3increases by 50%, • Due to the impact of placental hCG, sTSH decreases throughout pregnancy with the lower limit of normal in the 1st trimester being poorly defined

  10. RECOMMENDATION The following reference ranges are recommended: • 1st trimester, 0.1–2.5 mIU/L; • 2nd trimester, 0.2–3.0 mIU/L; • 3rd trimester, 0.3–3.0 mIU/L.

  11. OH and SCH in pregnancy • OHis defined as a TSH > 2.5 in conjunction with a decreased FT4or a TSH >10.0 irrespective of the FT4levels • SCHis defined as a TSH between 2.5 and 10 mIU/L with a normal FT4

  12. Adverse Outcomes Associated with OH in Pregnancy • OHin pregnancy has consistently been shown to be associated with an increased risk of adverse pregnancy complications, as well as detrimental effects upon fetal neurocognitive development • Specific adverse outcomes include increased risk of premature birth, LBW, miscarriage and gestational hypertension

  13. Adverse Outcomes Associated with SCHin Pregnancy • “the majority of scientific evidence suggests SCH is associated with increased risk of adverse pregnancy outcomes” • “an association between maternal SCH and adverse fetal neurocognitive development is biologically plausible though not clearly demonstrated”

  14. RECOMMENDATION • The recommended treatment of maternal hypothyroidism is LT4 • It is strongly recommended not to use other thyroid preparations such as T3 or desiccated thyroid.

  15. RECOMMENDATION • Hypothyroid patients on LT4 who are newly pregnant should increase their dose of LT4 by ~25%–30% • One simple suggestion for patients is to increase LT4 from once daily dosing to a total of nine doses per week • TSH should be monitored approximately every 4 wksduring the first half of pregnancy and once between 26 – 32 wks gestation

  16. Postpartum Pearls

  17. Who is at risk for developing postpartum thyroiditis? Any woman with: • Autoimmune disorders (such as Type1 dm) • Positive anti-thyroid antibodies • History of previous thyroid dysfunction including previous postpartum thyroiditis • Family history of thyroid dysfunction

  18. Postpartum Thyroiditis • Is the occurrence of thyroid dysfunction in the first year post partum in women euthyroidprior to pregnancy • In its classical form, transient thyrotoxicosis is followed by transient hypothyroidism with a return to the euthyroid state by the end of the first postpartum year • The thyrotoxic phase occurs 1-4 months after delivery and lasting for 1-3 months • The hypothyroid phase, typically occurs 4-8 months after delivery and may last up to 9 –12 months. • 1/3 of patients wilonly have a thyrotoxic or hypothyroid phase • Approximately 20% of those that go into a hypothyroid phase will remain hypothyroid.

  19. RECOMMENDATION • During the thyrotoxic phase of PPT, symptomatic women may be treated with beta blockers • Propranolol at the lowest possible dose is the treatment of choice • ATDs are not recommended for treatment of the thyrotoxic phase of PPT

  20. RECOMMENDATION • Women who are symptomatic during the hypothyroid phase of PPT should have their sTSHlevel retested in 4–8 wksor start on LT4 • Women who are asymptomatic during the hypothyroid phase of PPT should have their TSH level retested in 4–8 wks

  21. Case 2 • 56 yr old divorced firefighter referred for goitre • PMHx: hypertension • PSHx: hernia, vasectomy • Meds: micardis 80 mg od • FMHx: adopted • HPI: Patient noted to have a goitre on routine physical exam

  22. Case 2 • O/E BP 142/86 BMI = 26 HR = 76 • thyroid: • visible fullness over left lobe • on palpation well circumcribed nodule measuring approximately 2 cm • no lymphadenopathy • exam otherwise normal

  23. Thyroid Nodule Guidelines • Clinical risk factors predicting malignancy include: • history of neck radiation • family history of thyroid cancer • age < 30 yrs or > 60 yrs • male gender • rapid growth of nodule • voice hoarseness

  24. What would you do next?

  25. Thyroid U/S • U/S should be performed in all patients with known or suspected thyroid nodules • Various U/S features have been associated with a higher likelihood of malignancy • hypoechogenicity • increased intranodularvascularity • irregular margins • microcalcifications • abnormal lymph nodes

  26. RECOMMENDATION • Measure sTSHin the initial evaluation of a patient with a thyroid nodule. • If the serum TSH is subnormal, a thyroid scan should be performed to rule out a “hot nodule”

  27. Case 2 • Labs: sTSH = 2.2 • U/S: The thyroid gland is nodular in appearance. The largest nodule in the right lobe measures .9 x .6 x .5 cm. There is a dominant nodule in the left lobe measuring 2.4 x 1.4 x 1.2 cm. Cervical lymph nodes appear normal. Impression: Multinodular goitre with a dominant nodule in the left lobe.

  28. What would you do next?

  29. FNAB • FNA is the most accurate and cost-effective method for evaluating thyroid nodules • FNA is not recommended for subcentimeternodules unless clinical or U/S suggests high risk • Only solid nodules >1 cm should be evaluated, since they have a greater potential to be clinically significant cancers

  30. FNAB • In the presence of two or more thyroid nodules > 1 cm, those with suspicious U/S features should be aspirated • It is rarely necessary to biopsy more than 2 nodules • If a thyroid scan is available, do not biopsy “hot areas” • FNA is reported as one of six diagnostic categories

  31. FNAB

  32. Case 2 • FNAB: consistent with a follicular lesion, undetermined significance • Options: • Repeat U/S in 6 – 18 mos. and repeat FNAB if size has increased > 20% in 2 dimensions • Surgical excision (risk of malignancy = 5 – 15%)

  33. Case 3 • 54 yr old ER nurse referred for hyperthyroidism • PMHx: insomnia • PSHx: wisdom teeth • Meds: Ativan prn • FMHx: sister had PPT • HPI: Patient presents with a 3 mos history of intermittent tremor and palpitations and 2 mos history of 15 lb wt loss and heat intolerance

  34. Case 3 • O/E: • HR = 94 BMI = 24 • eyes: mild stare, no exophthalmos • mild tremor • thyroid: visibly enlarged, on palpation enlarged to 3 x normal no nodularity, non tender • LABS: • FT4 = 49 FT3 = 5.6 • sTSH < .01

  35. What would you do next?

  36. RECOMMENDATION • A RAI131uptakeshould be performed when the clinical presentation of thyrotoxicosis is not diagnostic of GD • A thyroid scan should ONLY be added in the presence of thyroid nodularity

  37. RAI 131 • Patient has a thyroid uptake which is elevated with a 24 hr uptake of 44% ( normal < 25 % )

  38. CAUSESOF THYROTOXICOSIS Thyrotoxicosis associated with a normal or elevated RAI131 uptake Graves Disease (GD) Toxic Adenoma (TA) or Toxic MNG RARE: TSH-producing pituitary adenomas, thyroid hormone resistance Thyrotoxicosis associated with a low RAI131 uptake Painless (silent) thyroiditis, acute thyroiditis, PPT Amiodarone-induced thyroiditis RARE: Iatrogenic , factitious

  39. Graves Disease • GD is an autoimmune disorder in which TRAbsstimulate the TSH receptor on the thyroid gland, increasing thyroid hormone production. • Overt thyrotoxicosis is characterized by elevated FT4 and FT3 and suppressed TSH (<0.01) • Subclinical hyperthyroidism is characterized by normal FT4 and FT3 and a suppressed TSH (<0.01) • There is only moderate correlation between elevation in FT4 and clinical signs /symptoms

  40. TREATMENT • Beta-adrenergic blockade should be given to elderly patients with symptomatic thyrotoxicosis or to any thyrotoxicpatient with resting HR > 90 bpm or coexistent cardiovascular disease

  41. TREATMENT • Patients with overt GD should be treated with any of the following modalities: • RAI131 therapy • antithyroid medication • thyroidectomy

  42. RAI 131 • Most patients respond to RAI131therapy with a normalization of FT4 and clinical symptoms within 4–8 weeks. • Hypothyroidism most commonly occurs between 2 - 6 months post treatment • Since TSH levels may remain suppressed for months after hyperthyroidism resolves, the levels should be interpreted only in concert with FT4

  43. Anti-Thyroid Drugs • The goal of the therapy is to render the patient euthyroid as quickly and safely as possible. These medications do not cure GD • Patients with mild disease, small goiters, and negative TRAb have a higher remission rate making the use of ATD more favorable in this group of patients • Treatment may have a beneficial immunesuppressiverole, but the major effect is to reduce the production of thyroid hormones and maintain a euthyroid state while awaiting a spontaneous remission

  44. RECOMMENDATION • Methimazole (Tapazole) should be used in virtually every patient who chooses ATD therapy for GD except … • Propylthiouracil (PTU) is preferred during the first trimester of pregnancy and in patients with minor reactions to methimazole who refuse RAI131therapy or surgery

  45. RECOMMENDATION • If methimazole is chosen as the primary therapy for GD, the medication should be continued for approximately 12–18 months, then tapered or discontinued if the TSH is normal • If a patient with GD becomes hyperthyroid after completing a course of methimazole, consideration should be given to treatment with RAI131 or surgery • Low-dose methimazole treatment for > 12–18 months may be considered in patients not in remission who prefer this approach

  46. Surgery • Thyroidectomy should be considered in: • patients with allergies, contraindications or non adherence with ATDs who cannot or will not pursue RAI131 • second trimester pregnancy, if surgery is indicated • patients with moderate to severe TAO.

  47. Case 3 • Patient elected initial treatment with RAI131 • Propranolol was initiated prior to RAI131 for management of tremor, palpitations +/- insomnia • Repeat bloodwork (FT4) will be done q 4-6 weeks post treatment • LT4 is started once FT4 is in low normal range

  48. THANK YOU FOR YOUR PARTICIPATION

  49. Questions ?

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