10/8- Disease of the Thyroid II Flashcards Preview

MS2 Endocrine > 10/8- Disease of the Thyroid II > Flashcards

Flashcards in 10/8- Disease of the Thyroid II Deck (40):
1

What is the most common cause/presentation of hyperthyroidism?

Graves disease

2

Graves' disease is the most common cause of what?

Thyrotoxicosis (hyperthyroidism)

- Excess thyroid hormone in the blood

3

How is Graves' disease diagnosed?

- TSH, fT4, T3 to establish toxicosis

- RAIU scan to differentiate toxic conditions

- Anti-TPO, TSI, if indicated

4

RAIU in hyperthyroid states- what conditions have high uptake?

- Graves'

- Toxic MNG

- Toxic Adenoma

5

RAIU in hyperthyroid states- what conditions have low uptake?

- Subacute Thyroiditis

- Iodine Toxicosis

-Thyrotoxicosis factitia

6

What is seen here? 

Q image thumb

Symptoms of Graves' disease hyperthyroidism:

- Exophthalmos: swollen soft tissues behind eye; pathognomonic

- Clubbing (thyroid acropachy)

- Pre-tibial edematous skin (non-pitting)

7

Clinical features of Graves' disease?

- Weight loss

- Increased appetite

- Palpitation, tachycardia or a-fib

- Breathlessness

- Eye complaints

- Goiter

- Gynecomastia

- Tremor

- Thyroid acropachy

- Pretibial myxoedema (many more)

8

Treatment for Graves' Disease?

- Beta blockers for symptoms

- Thionamide medications:

  • Methimazole: MMI is treatment of choice: fast acting, longer half-life
  • Propylthiouracil

- Radioiodine ablation: Avoid RAI in children and pregnancy!

- Surgery

  • Large goiters not amenable to RAI
  • Compressive symptoms

9

Timeline/prognosis of Graves' disease treated with Thionamide?

(Methimazole, Propylthiouracil)

MMI is treatment of choice: fast acting, longer half-life

- May re-establish euthyroidism in 6-8 weeks

- 40% - 60% incidence of disease remission

- 20% incidence of allergy (rash, itching)

- 0.5% incidence of potentially fatal agranulocytosis

10

What causes thyrotoxicosis with toxic adenoma?

Hyperfunctioning nodule

11

What are possible treatments for Toxic Adenoma (nodule)?

- Anti-thyroid medications

- Radioiodine

- Surgery

- Ethanol injection

12

Details of using radioiodine for treating toxic adenoma (nodule):

- Cure rate

- ASEs

- Risk of hypothyroidism

- Cure rate > 80% (20 mCi I131)

- 2nd dose of I131 needed in 10-20%

- Hypothyroidism risk 5-10%

- Pts who are symptomatically toxic may require control with thionamide medications before RAI to reduce risk of worsening toxicity

13

When is surgery preferred in treating toxic adenoma (nodule)?

- Risk of hypothyroidism

- Preferred for children and adolescents

- Preferred for very large nodules when high I131 doses needed

- Low risk of hypothyroidism

14

When is ethanol used to treat toxic adenoma (nodule)?

- Cure rate

- Rarely done in the US

- May achieve cure in 80%

15

What is Thyroid Storm?

- Prognosis

Dreaded complication in endocrinology: 

- Extreme form of hyperthyroidism

- Very high mortality

- Early diagnosis and aggressive therapy in ICU can be life-saving

- Careful follow-up after d/c from hospital

16

How should Thyroid Storm be treated?

- Admit to intensive care

- General supportive measures

- Beta-blockers (hyperadrenergic Sx)

- Hyperthyroidism:

  • Anti-thyroid drugs: Methimazole (always give first before iodine)
  • Steroids

- Iodine:

  • High doses for Wolff Chaikoff effect
  • NEVER give this before giving thionamides first (block formation of thyroid hormone with MMI and then prevent release with thionamides)

17

What is "apathetic hyperthyroidism"?

- Symptoms

- Epidemiology

Labs show hyperthyroid (elevated T4, normal TSH), but without many symptoms

- Lack of tremor, diaphoresis, heat-intolerance, hyperdefecation and other classic symptoms of sympathetic over-activity

- Less likely to have goiter

- Common symptoms:

  • Weight loss, anorexia
  • Constipation despite thyrotoxic
  • Tachycardia, Afib, CHF, angina
  • Cognitive dysfunction

Epidemiology:

- Elderly population

- TMNG more likely than in young (but Grave's still most common)

18

What is subclinical hyperthyroidism?

- Lab values

- Prognosis

- Indications for treatment

Labs:

- Low TSH

- Normal FT4 and FT3

Progression to overt hyperthyroidism is low

Indications to treat:

- Any cardiac disease (CAD, AFib, etc)

- Age > 60 (10 year risk AFIB 32%, 10% if normal TSH)

- Toxic MNG or toxic adenoma

- Osteoporosis

19

Describe the physiological function of Amiodarone and Thyroid?

- Increase iodine pool in body and therefore decrease RAIU.

- Decrease peripheral deiodination of T4 to T3.

20

Amiodarone can induce what?

- Timeline

Thyroid dysfunction:

- 3 mo- 4 yrs after starting

- Hypothyroidism (8%)

- Thyrotoxicosis (3%)

21

What are different types of hypothyroidism?

- Primary: thyroid gland failure

- Secondary: pituitary failure

- Tertiary: hypothalamic failure

- Peripheral resistance

22

How is hypothyroidism diagnosed (labs)?

- What should be done in each situation?

Primary (check for Abs):

- Low FT4

- High TSH

Secondary/Tertiary (TRH stimulation test, MRI):

- Low FT4

- Low TSH

23

How is hypothyroidism treated?

- Benefits of treatment?

Levothyroxine (T4) due to longer half life

- Don't take with food/supplements

Treatment prevents:

- Bone loss

- Cardiomyopathy

- Myxedema

24

What are some causes of hypothyroidism?

Agenesis- congenital

Thyroid destruction

- Hashimoto’s thyroiditis

- Surgery

- I131 ablation

- Infiltrative diseases

- Post-laryngectomy

Inhibition of function

- Iodine deficiency

- Iodine administration

- Anti-thyroid medications (PTU, Methimazole, Lithium, Interferon)

- Inherited defects

Transient:

- Post-partum

- Thyroiditis

25

Symptoms of hypothyroidism?

- Tiredness/malaise

- Weight gain

- Anorexia

- Cold intolerance

- Poor memory

- Depression

- Goiter

- Dry, brittle hair and skin

- Constipation

- Ataxia

- Slow-relaxing reflexes

- Deafness

- Loss of eyebrows

- Bradycardia

- Pericardial effusion

And more...

A image thumb
26

What is Levothyroxine?

- Uses

- Average dose

- Relationship to T3

- Results

Synthetic T4

- Most commonly prescribed treatment for hypothyroidism

- Dosing: avg 1.6 ug/kg

  • If > 50-60 yo or cardiac disease, must start at low dose (25 ug/d)
  • Recheck thyroid hormone levels every 4-6 wks after dose change
  • Aim for normal TSH level

- No T3 (but 85% of T3 comes from T4 conversion)

- All pts made euthyroid biochemically

27

What is Myedema Coma?

- Prognosis

- Treatment

Extreme for of hypothyroidism (mirror image of thyroid storm)

- Very high mortality

- Early diagnosis and aggressive therapy in ICU can be life-saving

- Careful follow up after d/c from hospital

28

What are the different types of thyroid cancer?

- Differentiated thyroid cancer

  • Papillary
  • Follicular

- Medullary thyroid cance

- Anaplastic cancer

29

Which is the most common subtype of thyroid cancer?

Papillary thyroid cancer

30

Peak incidence of papillary thyroid cancer?

- 30-50 yo

- 2-3x more in women

31

How does papillary thyroid cancer typically present?

- Mets?

- Physiological activity?

- Usually presents as a slowly growing neck mass

 - Local invasion may cause:

  • Cord paralysis
  • Dysphagia
  • Lymph node involvement Metastases occur to cervical and upper mediastinal LNs, and occasionally to the lungs

Physiology:

- Activation of receptor tyrosine kinases (RET/PTC, TRK, MET), appear to be specific for the transformation of thyroid follicular cells into papillary thyroid carcinomas

32

How is papillary thyroid cancer diagnosed?

- Treated?

Diagnosis by FNA

Treatment:

- Thyroidectomy +/- LN dissection

- Followed by radioiodine therapy and annual surveillance

33

Describe Follicular Thyroid Cancer?

- Prevalence

- Peak incidence

- 10-30% of thyroid cancers (2nd most common)

Peak incidence:

- 40-60 yo

- 3x more in women

34

Pathogenesis and prognosis of Follicular thyroid cancer?

- This cancer invades blood vessels early, with metastases to the lungs and bone being fairly common

- Mortality up to 50% at 10 yrs

- Metastases occur to cervical and upper mediastinal LNs, and occasionally to the lungs

35

How is follicular thyroid cancer diagnosed?

- Treated?

Diagnosed by FNA

Treatment:

- Thyroidectomy +/- LN dissection

- Followed by radioidone therapy and annual surveillance

36

Describe Medullary Thyroid Cancer

- Neoplasia of what

- Prevalence

- Survival rate

- Types

- Neoplasia of parafollicular cell

- 5-7% of all thyroid cancers

- Survival higher in absence of nodal involvement

Types:

- Sporadic

- Familial: could be related to multiple endocrine neoplasias types 2A/2B, associated with RET oncogene

37

How is medullary thyroid cancer diagnosed?

- Calcitonin estimations

- Genetic analysis for RET mutation

38

Describe anaplastic thyroid cancer:

- Neoplasia of what

- Prevalence

- Prognosis

- Undifferentiated tumors of the thyroid follicular epithelium

- 2-5% of all thyroid cancers

- Extremely aggressive; disease-specific mortality ~ 100%

- Early recognition of the disease is essential to allow prompt initiation of therapy

Epidemiology:

- Mean age at diagnosis is 65 yo

-

- 60 -70 % of tumors occur in women

39

What are the primary symptoms of anaplastic thyroid cancer?

Primary symptom = rapidly enlarging neck mass

- Occurs in ~ 85% of pts

40

Treatment for anaplastic thyroid cancer?

- Surgery

- Radiation

- Chemotherpay

In addition to supportive measures