Transcript Thyroid Guidelines - Welcome to the Huronia Nurse

Dr. D. Zatelny
BaSc, MD, FRCPC

Review practical primary care
management of 3 common thyroid
conditions through a case based
approach
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Encourage discussion !
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26 yr old married executive secretary referred for
possible hypothyroidism
PMHx: depression
 Meds: BCP
 FMHx: father had MI age 52 yrs.
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mother had Graves disease
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HPI: Patient c/o fatigue and weight gain
She is concerned she may be hypothyroid
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O/E BP 112/66 HR =74 bpm BMI = 30
eye exam normal
thyroid exam normal
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Labs: Hb = 116
ferriten = 9
sTSH = 6.2
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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
 LABS:
Bhcg +ve
sTSH = 5.8
FT4 = 15
TPOAb =1:764
TGAb = 1:66
Pregnancy is a stress test for the
thyroid
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The gland increases 10% in size
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Production of FT4 & FT3 increases by 50%,
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Due to the impact of placental hCG,
sTSH decreases throughout pregnancy
with the lower limit of normal in the 1st
trimester being poorly defined
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.
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OH is defined as a TSH > 2.5 in
conjunction with a decreased FT4 or a
TSH >10.0 irrespective of the FT4 levels
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SCH is defined as a TSH between 2.5 and
10 mIU/L with a normal FT4
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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
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Specific adverse outcomes include
increased risk of premature birth, LBW,
miscarriage and gestational hypertension
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“the majority of scientific evidence
suggests SCH is associated with increased
risk of adverse pregnancy outcomes”
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“an association between maternal SCH
and adverse fetal neurocognitive
development is biologically plausible
though not clearly demonstrated”
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The recommended treatment of maternal
hypothyroidism is LT4
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It is strongly recommended not to use
other thyroid preparations such as T3 or
desiccated thyroid.

Hypothyroid patients on LT4 who are newly
pregnant should increase their dose of LT4 by
~25%–30%
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One simple suggestion for patients is to
increase LT4 from once daily dosing to a total
of nine doses per week
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TSH should be monitored approximately
every 4 wks during the first half of pregnancy
and once between 26 – 32 wks gestation
Any woman with:
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Autoimmune disorders (such as Type1 dm)
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Positive anti-thyroid antibodies
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History of previous thyroid dysfunction including
previous postpartum thyroiditis
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Family history of thyroid dysfunction
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Is the occurrence of thyroid dysfunction in the first year post
partum in women euthyroid prior to pregnancy
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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
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The thyrotoxic phase occurs 1-4 months after delivery and
lasting for 1-3 months
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The hypothyroid phase, typically occurs 4-8 months after
delivery and may last up to 9 –12 months.
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1/3 of patients wil only have a thyrotoxic or hypothyroid phase
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Approximately 20% of those that go into a hypothyroid phase
will remain hypothyroid.
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During the thyrotoxic phase of PPT, symptomatic
women may be treated with beta blockers
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Propranolol at the lowest possible dose is the
treatment of choice
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ATDs are not recommended for treatment of the
thyrotoxic phase of PPT
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Women who are symptomatic during
the hypothyroid phase of PPT should
have their sTSH level retested in 4–8 wks
or start on LT4
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Women who are asymptomatic during
the hypothyroid phase of PPT should
have their TSH level retested in 4–8 wks
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56 yr old divorced firefighter referred for goitre
PMHx: hypertension
 PSHx: hernia, vasectomy
 Meds: micardis 80 mg od
 FMHx: adopted
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HPI: Patient noted to have a goitre on routine
physical exam
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O/E BP 142/86 BMI = 26 HR = 76
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thyroid:
› visible fullness over left lobe
› on palpation well circumcribed nodule
measuring approximately 2 cm
› no lymphadenopathy
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exam otherwise normal
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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
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U/S should be performed in all patients with
known or suspected thyroid nodules
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Various U/S features have been associated
with a higher likelihood of malignancy
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hypoechogenicity
increased intranodular vascularity
irregular margins
microcalcifications
abnormal lymph nodes
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Measure sTSH in the initial evaluation of
a patient with a thyroid nodule.
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If the serum TSH is subnormal, a thyroid
scan should be performed to rule out a
“hot nodule”
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Labs: sTSH = 2.2
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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.
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FNA is the most accurate and cost-effective
method for evaluating thyroid nodules
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FNA is not recommended for subcentimeter
nodules unless clinical or U/S suggests high risk
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Only solid nodules >1 cm should be evaluated,
since they have a greater potential to be clinically
significant cancers
 In the presence of two or more thyroid nodules
> 1 cm, those with suspicious U/S features should be
aspirated
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It is rarely necessary to biopsy more than 2 nodules
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If a thyroid scan is available, do not biopsy “hot
areas”
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FNA is reported as one of six diagnostic categories
Diagnostic Category
Nondiagnostic,
Benign
Risk of
Malignancy
1 – 4%
0.3%
Follicular lesion , undetermined significance
5 – 15%
Follicular or Hurtle cell neoplasm
15 – 30%
Suspicious for Malignancy
60 – 75%
Malignant
97 – 99%
 FNAB:
consistent with a follicular
lesion, undetermined significance
(risk of malignancy = 5 – 15%)
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Options:
› Repeat U/S in 6 – 18 mos. and repeat FNAB if
size has increased > 20% in 2 dimensions
› Surgical excision
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54 yr old ER nurse referred for hyperthyroidism

PMHx: insomnia
PSHx: wisdom teeth
Meds: Ativan prn
FMHx: sister had PPT
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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
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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
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A RAI131uptake should be performed
when the clinical presentation of
thyrotoxicosis is not diagnostic of GD
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A thyroid scan should ONLY be added in
the presence of thyroid nodularity
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Patient has a thyroid uptake which is
elevated with a 24 hr uptake of 44%
( normal < 25 % )
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
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GD is an autoimmune disorder in which TRAbs stimulate
the TSH receptor on the thyroid gland, increasing thyroid
hormone production.
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Overt thyrotoxicosis is characterized by elevated FT4 and
FT3 and suppressed TSH (<0.01)
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Subclinical hyperthyroidism is characterized by normal
FT4 and FT3 and a suppressed TSH (<0.01)
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There is only moderate correlation between elevation in
FT4 and clinical signs /symptoms
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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
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Patients with overt GD should be treated
with any of the following modalities:
› RAI131 therapy
› antithyroid medication
› thyroidectomy
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Most patients respond to RAI131therapy
with a normalization of FT4 and clinical
symptoms within 4–8 weeks.
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Hypothyroidism most commonly occurs
between 2 - 6 months post treatment
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Since TSH levels may remain suppressed for
months after hyperthyroidism resolves, the
levels should be interpreted only in concert
with FT4
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The goal of the therapy is to render the patient
euthyroid as quickly and safely as possible. These
medications do not cure GD
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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
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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
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Methimazole (Tapazole) should be used in
virtually every patient who chooses ATD
therapy for GD except …
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Propylthiouracil (PTU) is preferred during the
first trimester of pregnancy and in patients
with minor reactions to methimazole who
refuse RAI131therapy or surgery
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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
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If a patient with GD becomes hyperthyroid after
completing a course of methimazole,
consideration should be given to treatment with
RAI131 or surgery
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Low-dose methimazole treatment for > 12–18
months may be considered in patients not in
remission who prefer this approach
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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.
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Patient elected initial treatment with RAI131
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Propranolol was initiated prior to RAI131 for
management of tremor, palpitations +/- insomnia
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Repeat bloodwork (FT4) will be done q 4-6 weeks
post treatment
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LT4 is started once FT4 is in low normal range