10/8- Disease of the Thyroid II Flashcards
What is the most common cause/presentation of hyperthyroidism?
Graves disease
Graves’ disease is the most common cause of what?
Thyrotoxicosis (hyperthyroidism)
- Excess thyroid hormone in the blood
How is Graves’ disease diagnosed?
- TSH, fT4, T3 to establish toxicosis
- RAIU scan to differentiate toxic conditions
- Anti-TPO, TSI, if indicated
RAIU in hyperthyroid states- what conditions have high uptake?
- Graves’
- Toxic MNG
- Toxic Adenoma
RAIU in hyperthyroid states- what conditions have low uptake?
- Subacute Thyroiditis
- Iodine Toxicosis
- Thyrotoxicosis factitia
What is seen here?
Symptoms of Graves’ disease hyperthyroidism:
- Exophthalmos: swollen soft tissues behind eye; pathognomonic
- Clubbing (thyroid acropachy)
- Pre-tibial edematous skin (non-pitting)
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)
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
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
What causes thyrotoxicosis with toxic adenoma?
Hyperfunctioning nodule
What are possible treatments for Toxic Adenoma (nodule)?
- Anti-thyroid medications
- Radioiodine
- Surgery
- Ethanol injection
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
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
When is ethanol used to treat toxic adenoma (nodule)?
- Cure rate
- Rarely done in the US
- May achieve cure in 80%
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
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)
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)
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
Describe the physiological function of Amiodarone and Thyroid?
- Increase iodine pool in body and therefore decrease RAIU.
- Decrease peripheral deiodination of T4 to T3.
Amiodarone can induce what?
- Timeline
Thyroid dysfunction:
- 3 mo- 4 yrs after starting
- Hypothyroidism (8%)
- Thyrotoxicosis (3%)
What are different types of hypothyroidism?
- Primary: thyroid gland failure
- Secondary: pituitary failure
- Tertiary: hypothalamic failure
- Peripheral resistance
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
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
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
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…
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
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
What are the different types of thyroid cancer?
- Differentiated thyroid cancer
- Papillary
- Follicular
- Medullary thyroid cance
- Anaplastic cancer
Which is the most common subtype of thyroid cancer?
Papillary thyroid cancer
Peak incidence of papillary thyroid cancer?
- 30-50 yo
- 2-3x more in women
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
How is papillary thyroid cancer diagnosed?
- Treated?
Diagnosis by FNA
Treatment:
- Thyroidectomy +/- LN dissection
- Followed by radioiodine therapy and annual surveillance
Describe Follicular Thyroid Cancer?
- Prevalence
- Peak incidence
- 10-30% of thyroid cancers (2nd most common)
Peak incidence:
- 40-60 yo
- 3x more in women
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
How is follicular thyroid cancer diagnosed?
- Treated?
Diagnosed by FNA
Treatment:
- Thyroidectomy +/- LN dissection
- Followed by radioidone therapy and annual surveillance
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
How is medullary thyroid cancer diagnosed?
- Calcitonin estimations
- Genetic analysis for RET mutation
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
What are the primary symptoms of anaplastic thyroid cancer?
Primary symptom = rapidly enlarging neck mass
- Occurs in ~ 85% of pts
Treatment for anaplastic thyroid cancer?
- Surgery
- Radiation
- Chemotherpay
In addition to supportive measures
