Thyroid resident talk

1. Update on Thyroid Disease
Management
Grace Lee MD
Endocrinology

2. Objectives
Review diagnosis, work-up, and treatment of:
Hypothyroidism
Hyperthyroidism
Thyroid nodules

5. Thyroid lab tests 101
TSH – Thyroid stimulating hormone
made by the pituitary
best screening test, most sensitive
thyroid function over 6-8 weeks
TSH
Free T4
Free T4 – Free thyroxine level
made by the thyroid
much less sensitive test

6. Thyroid function tests: diagnosis
TSH
Decreased
Hyperthyroidism**
Increased
Hypothyroidism
** with the exception of
central hypothyroidism
(pituitary disease)

7. Hypothyroidism
5% of population
Differential diagnosis of elevated TSH normal free T4:
Nonthyroidal illness recovery stage
TSH secreting pituitary adenomas (high normal T4)
TSH resistance
Causes:
Autoimmune thyroiditis (90% of all cases have + TPO ab)
Drugs:
??
Other causes?

8. Hypothyroidism
5% of population
Differential diagnosis of elevated TSH normal free T4:
Nonthyroidal illness recovery stage
TSH secreting pituitary adenomas (high normal T4)
TSH resistance
Causes:
Autoimmune thyroiditis (90% of all cases have + TPO ab)
Drugs:
amiodarone, lithium, interferon alpha, IL-2
Partial thyroidectomy
Transient hypothyroidism due to thyroiditis
Central hypothyroidism (pituitary disease)
Iodine deficiency or excess

9. Subclinical Hypothyroidism
4% of population has subclinical
hypothyroidism (NHANES Hollowell
JCEM 2002)
The annual rate of progression to overt
hypothyroidism ranges from 2 to 4
percent.
Mixed studies : CAD, CHF, mortality

10. Hypothyroidism – when to treat
TSH > 10 Everyone (ATA, ETA guidelines)
TSH upper range normal -10
(controversial, ATA, AACE 2012)
Signs/symptoms hypothyroidism
+ TPO (thyroid peroxidase) antibodies
Infertility or attempting conception
Could opt not to treat > 65

11. Hollowell JCEM 2007
TSH right shifts over time

12. Feller M et al, JAMA 2018

13. How to treat
Healthy < 65:
Start 1.6 mcg/kg ideal body weight
OK to start full/near full dose
Women: 75-125 mcg daily
Men 100-150 mcg daily
>65 or CAD
Start 25 mcg daily
Increase by 25 mcg every 4-6 weeks
Measure TSH in 4-6 weeks

14. When is a low TSH (< 0.5) OK?
Thyroid cancer – thyroid hormone is chemotherapy
consult specialist about target TSH and dosing
Panhypopituitarism – follow Free T4, not TSH
(Free T4 should be mid-range of normal)

15. How to take levothyroxine
1. First thing in the morning
2. On an empty stomach
3. Wait 1 hour before eating
dairy, soy, coffee bind
levothyroxine
4. Wait 4 hours before taking
calcium, iron, multivitamins

16. Hyperthyroidism
Symptoms:
Younger patient: weight loss, heart racing, palpitations,
Decrease ability to concentrate, insomnia, tremors, anxiety
Older patient: fatigue, weight loss/gain, slowed motor function.
PE:
Heart rate, rhythm
Tremors
Exopthalmos
Thyroid – enlarged? Symmetric vs. asymmetric?

17. Work up
● Radioactive iodine uptake and scan is gold
standard
● Thyrotropin receptor antibodies (TRAb)
Sensitivity and specificity of 97 and 99 percent for
diagnosing Graves' disease (Barbesino G JCEM 2013)
● Pathognomonic for Grave’s disease:
Exopthlamos
Pretibial nonpitting edema

18. Differential Diagnosis
E

19. Differential Diagnosis
E
Also, exogenous
Thyroid uptake

20. Grave’s disease medical therapy
Up to 1/3 of patients may spontaneously remit
after 18 months of antithyroidal therapy.
Good candidates have these characteristics:
Female age > 40*
Mild hyperthyroidism
Small goiter

21. Radioablation for Grave’s disease
Dose is based on how much iodine the thyroid uptakes in
24 hours and also size of thyroid.
Dosed to kill the thyroid.
If dose to maintain euthyroid, most (over 2/3) will
become hyperthyroid in the next 10 years less than one-
third of patients are euthyroid 10 years after therapy.
Sridama V Engl J Med 1984
Time course: usually takes 12-15 weeks, may take up to 6
months.
If after about 6 months still not euthyroid, then consider re-
ablation (20% cases)

22. Side effects of Methimazole
Up to 20% may get allergic rash
Reversible cholestasis
1/300 neutropenia.
If on methimazole for Grave’s disease,
generally no more than 18 mo - 2 years total.

23. Thyroid masses

24. Thyroid Nodules
● 5% of thyroid nodules are cancerous
● Incidentally found in up to 50% of population
● Thyroid cancer relatively low risk disease

25. Thyroid exam
Common
mistakes:
Palpating too
high
Not palpating
hard enough
Not making sure
nodule moves
with swallowing

26. Normal Asymmetric Symmetric

27. Risk Factors
●Children
●Adults less than 30 years of age
●Patients with a history of head and neck irradiation
Dose and age dependent
Risk lasts at least lasts 40 years
●Patients with a family history of thyroid cancer
MEN2
Familial Adenomatous Polyposis
(Cowden Syndrome)

28. Other increased risk populations
● Nonthyroidal cancer: may be increased?
41 patients with thyroid nodules, 16 had
surgery, 9/16 had cancer
● PET Scans incidental nodules: 35% had
thyroid cancer with focal uptake (Soelberg et
al, Thyroid 2012)
● History of radiation exposure:
7% had thyroid cancer (Piccardo A et al Q J
Nucl Med 2012)

29. ATA guidelines 2018

30. Sonographic
pattern
Ultrasound features
Malignancy
Risk
Consider
biopsy
High
suspicion
Hypoechoic PLUS
Irregular margins
Microcalcifications,
Taller than wide shape,
Rim calcifications + extrusion
Extrathyroidal extension
>70 to 90% FNA at >1 cm
Intermediate
suspicion
Hypoechoic solid nodule
No worrisome features
10 to 20% FNA at >1 cm
Low
suspicion
Isoechoic or hyperechoic solid
nodule, cystic/solid,
No worrisome features
5 to 10%
FNA at >1.5
cm
Very low
suspicion
Spongiform or partially cystic
No worrisome features
<3%
FNA at >2 cm
Observation
also
reasonable
ATA guidelines 2018

36. Levothyroxine dose ↑ 47 % during first ½ of pregnancy
Increase usually occur at 8 weeks but as early as 5 weeks
Alexander EK N Engl J Med 2004 Jul 15;351(3):241-9.
Prepregnancy: goal TSH between 1-2.5
Once, pregnant by UPT, increase to:
Monday-Friday once daily usual dose
Saturday and Sunday increased dose
4-6 weeks later, recheck TSH
Make sure patient takes prenatal MVI at least 4 hrs later
Thyroid disease and pregnancy

37. How about T3?
No
Clinical trials have shown benefit on being on T3/T4
Combinations vs. levothyroxine. In fact in most studies,
Patients felt better on levothyroxine.,
Armour thyroid has inconsistent amounts of T3/T4 per batch.
Concerns for mad cow disease.
Supraphysiologic doses of T3 compared to humans

38. Armour thyroid dot phrase
In the past (50 years ago...) many meds were purified
from animals (insulin, thyroid, etc.) but now with
technology most of these meds have been replaced
by synthetic medications. It turns out the the pig and
cow thyroid has both T3 and T4 in it- usually about
1/4 T3 and 3/4 T4. The actual content varies from
animal to animal and from tablet to tablet. Although
some doctors and patients believe that this
medication works better than the synthetic T4, this
has not been demonstrated in high quality published
clinical trials. Most (nearly all) thyroid experts
recommend T4 alone as the body converts the T4 to
T3 as needed. For these reasons I prescribe T4
(levothyroxine) for my patients with hypothyroidism.
Courtesy Dr. Marc Jaffe