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 PMHx: depression Meds: BCP FMHx: father had MI age 52 yrs.
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 Labs: Hb = 116
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 & FT3 increases 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
OH is defined as a TSH > 2.5 in conjunction with a decreased FT4 or a
TSH >10.0 irrespective of the FT4 levels
SCH is defined as a TSH between 2.5 and 10 mIU/L with a normal FT4

12. Adverse Outcomes Associated with OH in Pregnancy
OH in 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 SCH in 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 wks during 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 euthyroid prior 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 wil only 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 sTSH level retested in 4–8 wks or 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: exam otherwise normal
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 intranodular vascularity
irregular margins
microcalcifications
abnormal lymph nodes

26. RECOMMENDATION
Measure sTSH in 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 subcentimeter nodules 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 Diagnostic Category Risk of Malignancy Nondiagnostic, 1 – 4%
Benign
0.3%
Follicular lesion , undetermined significance
5 – 15%
Follicular or Hurtle cell neoplasm
15 – 30%
Suspicious for Malignancy
60 – 75%
Malignant
97 – 99%

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: LABS: eyes: mild stare, no exophthalmos mild tremor
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 = FT3 = 5.6
sTSH < .01

35. What would you do next?

36. RECOMMENDATION
A RAI131uptake should 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. CAUSES OF 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 TRAbs stimulate 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 thyrotoxic patient 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 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 immunesuppressive role, 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 ?