10/8- Disease of the Thyroid II Flashcards
1
Q
What is the most common cause/presentation of hyperthyroidism?
A
Graves disease
2
Q
Graves’ disease is the most common cause of what?
A
Thyrotoxicosis (hyperthyroidism)
- Excess thyroid hormone in the blood
3
Q
How is Graves’ disease diagnosed?
A
- TSH, fT4, T3 to establish toxicosis
- RAIU scan to differentiate toxic conditions
- Anti-TPO, TSI, if indicated
4
Q
RAIU in hyperthyroid states- what conditions have high uptake?
A
- Graves’
- Toxic MNG
- Toxic Adenoma
5
Q
RAIU in hyperthyroid states- what conditions have low uptake?
A
- Subacute Thyroiditis
- Iodine Toxicosis
- Thyrotoxicosis factitia
6
Q
What is seen here?
A
Symptoms of Graves’ disease hyperthyroidism:
- Exophthalmos: swollen soft tissues behind eye; pathognomonic
- Clubbing (thyroid acropachy)
- Pre-tibial edematous skin (non-pitting)
7
Q
Clinical features of Graves’ disease?
A
- Weight loss
- Increased appetite
- Palpitation, tachycardia or a-fib
- Breathlessness
- Eye complaints
- Goiter
- Gynecomastia
- Tremor
- Thyroid acropachy
- Pretibial myxoedema (many more)
8
Q
Treatment for Graves’ Disease?
A
- 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
Q
Timeline/prognosis of Graves’ disease treated with Thionamide?
A
(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
Q
What causes thyrotoxicosis with toxic adenoma?
A
Hyperfunctioning nodule
11
Q
What are possible treatments for Toxic Adenoma (nodule)?
A
- Anti-thyroid medications
- Radioiodine
- Surgery
- Ethanol injection
12
Q
Details of using radioiodine for treating toxic adenoma (nodule):
- Cure rate
- ASEs
- Risk of hypothyroidism
A
- 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
Q
When is surgery preferred in treating toxic adenoma (nodule)?
- Risk of hypothyroidism
A
- Preferred for children and adolescents
- Preferred for very large nodules when high I131 doses needed
- Low risk of hypothyroidism
14
Q
When is ethanol used to treat toxic adenoma (nodule)?
- Cure rate
A
- Rarely done in the US
- May achieve cure in 80%
15
Q
What is Thyroid Storm?
- Prognosis
A
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
Q
How should Thyroid Storm be treated?
A
- 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
Q
What is “apathetic hyperthyroidism”?
- Symptoms
- Epidemiology
A
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
Q
What is subclinical hyperthyroidism?
- Lab values
- Prognosis
- Indications for treatment
A
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
Q
Describe the physiological function of Amiodarone and Thyroid?
A
- Increase iodine pool in body and therefore decrease RAIU.
- Decrease peripheral deiodination of T4 to T3.
20
Q
Amiodarone can induce what?
- Timeline
A
Thyroid dysfunction:
- 3 mo- 4 yrs after starting
- Hypothyroidism (8%)
- Thyrotoxicosis (3%)
21
Q
What are different types of hypothyroidism?
A
- Primary: thyroid gland failure
- Secondary: pituitary failure
- Tertiary: hypothalamic failure
- Peripheral resistance
22
Q
How is hypothyroidism diagnosed (labs)?
- What should be done in each situation?
A
Primary (check for Abs):
- Low FT4
- High TSH
Secondary/Tertiary (TRH stimulation test, MRI):
- Low FT4
- Low TSH
23
Q
How is hypothyroidism treated?
- Benefits of treatment?
A
Levothyroxine (T4) due to longer half life
- Don’t take with food/supplements
Treatment prevents:
- Bone loss
- Cardiomyopathy
- Myxedema
24
Q
What are some causes of hypothyroidism?
A
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...
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
- \< 10% are younger than 50 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
