Thyroid Disorders Flashcards
Hypothyroidism and Hyperthyroidism thyroid hormone levels?
TSH
T4
T3
Hypothyroidism
TSH- high
T4- Low
T3- low
Hyperthyroidism
TSH-low
T4- high
T3- low
What is a goiter?
Whats the most common cause of goiters and what is the mechanism?
Abnormal growth of the thyroid gland
Iodine deficiency most common cause world wide—mechanism?
Iodine rich foods…..sea vegetables, yogurt, cheese, navy beans, strawberries, potatoes, shellfish, eggs, shrimp, sardines
What are the most common causes in the US?
3
- Multinodular goiter (most common in elderly)
- Chronic autoimmune (Hashimoto’s) thyroiditis
- Grave’s disease
Goiter Obstructive Symptoms
3
- Monotone voice
- Dysphagia (difficulty swallowing)
- Tracheal compression
Test for Diagnosis for goiter?
if this test is high what should we measure?
Most common cause?
If this test is low what should we do? 3
What is the most common disease?
Obtain TSH:
If high—measure serum free T4—Diagnosis?
Most common cause is Hashimoto’s thyroiditis
- If low—measure free T4, serum total T3—Diagnosis?
- Consider Ultrasound
- Need 24-hour radioiodine uptake scan
Multinodular goiter/Grave’s disease most common
Most common cause of hypothyroidism?
There are three types. What are they?
Most common cause is Hashimoto’s Thyroiditis
Three types – Primary, Secondary and Tertiary
Primary Hypothyroidism causes?
7
- Iodine deficiency
- Autoimmune: Hashimoto’s
- Iatrogenic: Iodine-131 therapy, thyroidectomy
- Post Partum Thyroiditis
- Drug induced: Lithium, Amiodarone, antithyroid drugs
- Congenital: agenesis, dysgenesis, hypoplastic
- Adult onset: normal aging
Secondary Hypothyroidism causes?
5
- Neoplasm
- Surgery
- Post partum necrosis
- Cushing’s
- Radiation
Tertiary Hypothyroidism causes?
3
- Hypothalamus dysfunction
- Hemochromatosis
- Sarcoidosis
Things you will find in the history for hypothyroidism?
10
- Fatigue
- Cold intolerance
- Weakness
- Lethargy
- Weight gain
- Constipation
- Myalgias
- Arthalgias
- Menstrual irregularities
- Hair loss
Physical findings for hypothyroidism?
7
- Dry, course skin
- Hoarse voice
- Brittle nails
- Periorbital, Peripheral edema (myxedema)
- Delayed reflexes
- Slow reaction time
- Bradycardia
Diagnosing Hypothyroidism
The thyroid-stimulating hormone (TSH) level is elevated. What does this indicate?
2
- indicating that thyroid hormone production is insufficient to meet metabolic demands
- free thyroid hormone levels are depressed
Can have “sub-clinical hypothyroidism.” What will your lab levels look like?
3
T3, T4 are within normal limits but TSH mildly elevated
Hypothyroidism treatment?
Thyroid hormone: usually 100 to 200 mcg daily
Can start with 50-100mcg QD
Levothyroxine (T4) {Synthroid}
-monitor TSH for response
Hypothyroidism treatment in the elderly?
In the elderly, start with 25-50 mcg and increase by 25 mcg every 2-3 weeks
Levothyroxine (T4) {Synthroid}
-monitor TSH for response
Monitoring Thyroid Function:
Patients with an intact hypothalamic-pituitary axis how should we monitor?
How about patients with a pituitary insufficiency?
Follow with serial TSH measurements
Measurements of free T4 and T3
How often should we monitor hypothyroidism?
8-12 weeks
We should have stable dosing until the 7th decade. Why would we have to adjust it then?
With age, thyroid binding may decrease, and the serum albumin level may decline. In this setting, the Levothyroxine dosage may need to be reduced by up to 20 percent
Hypothyroidism
syndromes?
3
Hashimotos Thyroiditis
Myxedema
Subclinical Hypothyroidism
Whats the most common form of thyroiditis?
Whats another name for it?
What disease can it be associated with?
Hashimoto’s Thyroiditis
AKA chronic lymphocytic thyroiditis
It can be associated with non-Hodgkins lymphoma (NHL)
What kind of disorder is hashimoto’s?
When in life does it usually occur?
Where is this the most common cause of hypothyroidism?
Autoimmune disorder
Usually occurs between the third and sixth decade
Most common cause of hypothyroidism in areas where there is sufficient iodine
Hashimoto’s Thyroiditis
has what thyroid antigens that cause the autoimmune disease? 3
Precipitating factors for hashimoto disease? 4
- Thyroglobulen (Tg)
- Thyroid peroxidase (TPO)
- The thyrotropin (TSH) receptor
- Infection
- Stress
- Sex steroids, pregnancy
- Radiation exposure
Most common signs and symptoms of Hashimoto’s?
7
- Painless goiter
- Fatigue
- Muscle weakness
- Weight gain
- Feeling of fullness in the throat
- Neck pain, sore throat, or both
- Low-grade fever
Thyroid Scan-iodine marked with radioactive tracer. What does this test detect?
camera can detect how much of the tracer is taken up by the thyroid
Labs to do for Hashimotos?
4
Imaging to do for Hashimotos?
2
- TSH,
- Free T4
- TPOAb (anti-thyroid peroxidase antibody)
- TGAb (anti-thyroglobin antibodies)
- ultrasound to establish goiter size
- Radioiodine uptake
Treatment for Hashimoto’s?
What should we monitor?
Thyroid hormone replacement:
Levothyroxine (T4) (Levothyroid, Synthroid)
Monitoring of TSH is best and most reliable
Levothyroxine (T4) (Levothyroid, Synthroid) for patients with:
under 60 w/o CAD?
pregnant women?
over 60 or pts with CAD?
50-100mcg daily – under 60 w/o CAD
100-150mcg daily – pregnant women
12.5-50mcg daily – over 60 or pts with CAD
Mild thyroid failure is a common disorder that frequently progresses to overt hypothyroidism. What are strong predictors of this?
4
- Anti-TPO antibodies
- TSH >20
- Radioiodine ablation Hx (Grave’s Disease)
- Other radiation therapies
Populations at Risk for
Subclinical Hypothyroidism
5
- Women
- Prior history of Graves disease or postpartum thyroid dysfunction
- Elderly
- Other autoimmune disease
- Family history of
- Thyroid disease
- Pernicious anemia
- Type 1 Diabetes mellitus
Subclinical Hypothyroidism
Treatment and why?
In the absence of positive antibodies?
When should we consider treatment without positive antibodies?
2
Levothyroxine therapy is recommended in those patients with positive antibodies because they are at greatest risk to progress to overt hypothyroidism
Asymptomatic TSH less than 10mU/L - follow their TSH
TSH>10mU/L
TSH less than 10mU/L who are pregnant or have manifestations such as goiter, lipid abnormalities, anovulatory menses
Myxedema is thought to be related to what?
thought to be related to connective tissue proliferation in reaction to increased to TSH levels
The Myxedem patient will usually have a history of what?
WHo does it usually develop in?
Symtpoms? 4
hypothyroidism
Develops in older adults
- Droopy eyelids
- Lethargy, fatigue, mental sluggishness
- Decreased reflexes
- Mucopolysaccharide infiltration of the dermal space
Mucopolysaccharide infiltration of the dermal space in Myxedema causes what?
3
- Facial puffiness
- Periorbital edema
- Non-pitting pretibial edema
Treatment for Myxedema?
2
- Thyroid hormone replacement
Levothyroxine (T4) (Levothroid, Synthroid) - Monitor TSH
Hyperthyroidism is also known as?
What is the most common cause?
AKA Thyrotoxicosis or Toxic diffuse goiter
The most common cause is Grave’s Disease.
Pathology of Graves Disease?
Describe the onset?
WHo does it occur in most commonly?
- Auto-immune d/o….appears suddenly
- Body produces antibodies to the receptor for TSH
It occurs most commonly in women between the ages of 20 and 40.
Common etiology of hyperthyroidism? 3
Less common etiologies of hyperthyroidism? 3
Rare etiologies?
5
Common:
- Graves’ Disease
- Toxic Adenoma (solitary)
- Toxic Multinodular Goiter
Less common:
- Subacute thyroiditis
- Hashimoto’s thyroiditis with transient hyperthyroid state
- Postpartum thyroiditis
Rare:
- Struma ovarii
- Hydatiform mole
- Metastatic thyroid cancer
- TSH secreting pituitary tumor
- Pituitary resistance to T3 and T4
Hyperthyroidism that cannot be correlated to the endocrine system is usually what?
a malignancy, i.e small cell carcinoma or carcinoid
Hyperthyroidism symtpoms?
7
- Nervousness
- Diaphoresis
- Heat intolerance
- Palpitations
- Fatigue
- Weight loss
- Frequent bowel movements
Hypertyroidism signs?
9
- Tachycardia
- Goiter
- Skin changes (pretibial myxedema)
- Tremor
- Eye signs (exophthalmos)
- Conjunctival inflammation,
- Extraocular muscle dysfunction
- Lid lag
- Osteoporosis
Laboratory findings in Hyperthyroidism?
4
- TSH - Low
- Free T4 - High
- TSI (thyroid-Stimulating Immunoglobulin) may be elevated in Graves’ Disease
- Radioactive Iodine uptake ?
Hyperthyroid Treatment? 2
MOA?
Anti-Thyroid Drugs (thioamides):
- Methimazole (Tapazole) 5-15mg/day (once daily)
- Propylthiouracil (PTU) 100-150mg/day
Both act by inhibiting iodine orgnaification
Side effects of Anti-Thyroid Drugs (thioamides):
Common? 4
Rare? 4
Common:
- pruritus,
- arthralgia’s,
- GI distress,
- metallic taste
RARE:
- agranulocytosis,
- hepatitis (PTU),
- aplastic anemia,
- thrombocytopenia
What labs would you get prior to starting Side effects of Anti-Thyroid Drugs (thioamides)?
3
CMP (LFT)
CBC
The usual workup
Whats the most widely reccommended permanent treatment of hyperthyroidism?
80-90% of injected I-131 is absorbed by the hyperplastic, toxic thyroid gland within?
What can this treatment worsen transiently?
Post treatment precautions?
Pretreatment precautions?
Most common side effect?
Radioactive Iodine Treatment
within 1 day of injection
Can worsen Grave’s ophthalmopathy transiently
Post treatment precautions:
Limit exposure to others for one week
Pretreatment:
Stopping thyroid hormone replacement…high levels of TSH encourage uptake of the RI by the thyroid
Most common side effect ? Yes, hypothyroidism
What is a permanent cure for hyperthyroidism?
How often is it done?
Side effects? 2
Surgical Removal of the Gland
Used about 1% of the time
PTU
High concentration iodides
Symptomatic Treatment
of hyperthyroidism?
For patients with temporary forms of hyperthyroidism what should we do?
When should we discontinue treatment?
- Beta Blockers – Propanolol:
Initial dose: 40 mg orally twice a day
Maintenance dose: 120 to 320 mg/day
beta blockers may be the only treatment required
Discontinue with symptom resolution
Hyperthyroidism syndromes?
5
- Grave’s Disease
- Multinodular Goiter
- Factitious hyperthyroidism
- Thyroid Storm
- Thyroiditis
What is an Organ-specific autoimmune disorder that causes hyperthyroidism?
What is the Pathology behind this disease?
Grave’s disease
The body creates circulating antibodies for the thyroid
What are the common autoimmune antibodies in grave’s disease?
3
- antithyroperoxidase (anti-TPO)
- antithyroglobulin (anti-TG) antibodies
- thyroid-stimulating immunoglobulin (TSI)
The autoantibody TSI is directed towards what in the body?
What does it act as?
What does it bind to and what does this cause?
TSI is directed toward follicles of the thyroid-stimulating hormone (TSH) receptor and acts as a TSH-receptor agonist
Similar to TSH, TSI binds to the TSH receptor on the thyroid follicular cells to activate thyroid hormone synthesis and release, and thyroid growth (hypertrophy)
Grave’s disease Tetrad of symptoms?
4
- Nontender, smooth, symmetric thyroid enlargement
- Thyrotoxicosis – hyperthyroid state
- Exopthalmosis
- Pretibial myxedema
Grave’s disease physical exam findings? 2
Older individuals may have apathetic hyperthyroidism. What does this cause?
6
Extremely thin digits
Excess sweating
- Flat affect
- Weight loss
- Emotional lability
- Atrial fibrillation
- CHF
- Muscle weakness
Grave’s disease labs?
2
What is the most specific autoantibody for autoimmune thyroiditis?
What are tests that can also help establish the diagnosis?
2
TSH-low
T4-high
an enzyme-linked immunosorbent assay (ELISA) for TSHR-Ab levels
- TSI, if elevated, helps establish the diagnosis of Graves disease
- RAIU (Radioactive Iodine Uptake)
RAIU (Radioactive Iodine Uptake) would look like what?
Much more uptake so the image would be much larger and darker
Treatment of Grave’s disease?
5
Antithyroid drugs –
- Propylthiouracil (PTU) and
- Methimazole (Tapazole) for at least 12 to 18 months.
- Beta Blockers – Propanolol (Inderal)
- Radioactive Iodine (some physicians use steroids with RAI due to worsening of exophthalmos with use of RAI.)
- Surgery
What do beta blockers help with for grave’s disese?
2
- Prevents the peripheral conversion of T4 to T3
2. Decreases Blood Pressure and rate of the heart
Multinodular Goiter
“Plummers Disease”
is characterized by what?
Disease usually in what age groups?
Common in what kind of areas?
Characterized by functionally autonomous nodules
Disease of older individuals
Common in areas of iodine insufficiency
Pathology of Multinodular Goiter
“Plummers Disease”?
What may they present with?
Caused by hyperplasia of the follicular cells whose activity becomes independent of TSH
May present with subclinical hyperthyroidism
How do we diagnosis Pathology of Multinodular Goiter
“Plummers Disease”?
4
Diagnosis:
- suppressed TSH
- markedly elevated T3
- moderately elevated T4
- thyroid scan with multiple functioning nodules
Factitious Hyperthyroidism
is also called what?
What is it caused by?
What kind of people could this be seen in? 3
T3 and T4 are ? and TSH is ? as is serum thyroglobulin concentration
AKA thyrotoxicosis factitia
- Ingestion of Levothyroxine by euthyroid patients
- May be iatrogenic
May be seen in 1. health care workers, 2. dieters, 3. body builders…Munchausen syndrome Usually an attempt to lose weight
high
low
Thyrotoxicosis will have what kinf of T3/T4 levels?
What can it be caused by? 2
Is there a history of hyperthyroidism?
Elevated T3 and/or T4
- Sometimes due to inflammation of the thyroid
- Can occur after ingestion of exogenous hormone (i.e. buying levothyroxine over the counter in Mexico as a “weight loss agent”
Usually no history of hyperthyroid condition
What is a thyroid storm and what are its precipitating factors?6
Life-threatening crisis…..one of those rare endocrine emergencies
Precipitating factors:
- Hyperthyroidism
- Stress
- Infection (usually respiratory)
- Diabetic ketoacidosis
- Physical or emotional trauma
- Manipulation during thyroidectomy
Thyroid storm clinical features?
4
- Very high fever
- Cardiovascular effects
- CNS effect
- Nausea & vomiting
Thyroid storm Rapid diagnosis and treatment?
5
- Peripheral cooling (cold packs and cooling mattress)
- Replace fluids, glucose and electrolytes
- Propranolol to block effects of T4 on cardiovascular function
- Glucocorticoids to correct adrenal insufficiency and to inhibit peripheral conversion of T4 to T3
- Propylthiouracil (PTU) and Methimazole (Tapazole) to block thyroid synthesis
What are the three classifications of thyroiditis?
What does it usually present as and what is this due to?
How can it be distinguished from other causes of thyroiditis?
Classified as Acute, Subacute and Chronic
Usually presents clinically as hyperthyroidism due to leakage of preformed thyroid hormone, though most patients ultimately develop hypothyroidism
Can be distinguished from other causes of thyroiditis as the RAIU is low
Acute Thyroiditis is a rare complication of what?
How does it present? 3
If blood cultures are negative, what may be tried to identify the organism?
How is this usually treated?
2
A rare complication of septicemia
Presents with
- fever,
- redness of the skin over the thyroid and
- tenderness** of the thyroid
aspiration of the thyroid gland
Usually treated with IV antibiotics, though occasionally I&D of the gland may be required
Subacute thyroiditis is also known as? 2
Probably secondary to what?
WHat is it characterized by? 3
What lab is high?
What does the thyroid scan show?
Treatment of choice?
de Quervain’s thyroiditis or Granulomatous thyroiditis
Probably secondary to a viral infection
Characterized by
- fever and
- anterior neck pain.
- Exquisitely tender thyroid gland
ESR is high
Thyroid scan shows little or no uptake of radioiodine
Treatment of choice is symptomatic
Complete resolution of symptoms in 90% of patients within months
Postpartum (Subacute Lymphocytic Thyroiditis)
onset?
The presence of what increases the risk in pregnant women?
What increases the risk of occurrence?
Onset is within 3-12 months post delivery
Presence of TPO anitibodies increases risk
Increased risk of reoccurrence with subsequent pregnancies
25-20% will progress to hypothyroidism within 5 years of delivery
Postpartum (Subacute Lymphocytic) symptoms?
2
- Thyroid gland is NONTENDER
2. Low uptake of RAI
Postpartum (Subacute Lymphocytic) treatment?
3
- Propanolol for tremors and tachycardia
- If hypothyroidism develops, Levothyroxine for 6 months to restore normal function
- Those who go on to develop permanent hypothyroidism will have to take Levothyroxine for life
Iodine Induced – (Jod-Basedow) thyroiditis:
Induced by what?
How do we diagnosis this? 2
Induced by contrast agents for angiography or CT scan
- Low uptake of radioactive iodine
- Absence of antithyroid antibodies
Amiodarone Induced thyroiditis:
What is amiodarone?
There are two types. Describe them?
Iodinated drug with antiarrhythmic and antianginal properties
Type 1 – occurs in patients w/ underlying thyroid disease
Type 2 – occurs in normal thyroids
Chronic thyroiditis types?
2
Hashimoto’ s thyroiditis : Previously discussed
Riedel’s struma
What is Riedel’s struma (who is it seen in? What is wrong with the gland? What does it cause? 3) and how do we treat it?2
(invasive fibrous thyroiditis) is a rare form of thyroiditis seen in middle aged women. The gland is stony hard and adherent to the surrounding structures and may cause symptoms of compression (dysphagia, dyspnea or hoarseness)
Treatment: Tamoxifen, steroids
Most common endocrine problem in the US?
Thyroid Nodules
Thyroid Nodules
are what?
Do they come is groups or solitary?
How are they discovered?
How do they appear on an RAIU?
Most often benign neoplasms from follicular epithelium
Usually solitary
Often painless, often discovered during a routine physical exam
Appear as “cold nodules” on RAIU scan
Solitary Thyroid Nodule
High risk factors for malignancy
History? 7
Physical findings? 5
Lab/imaging? 3
Treatment?
History:
- head and neck irradiation, 2. exposure to nuclear radiation,
- recent onset,
- rapid growth,
- young age,
- male sex,
- familial incidence
Physical:
- hard consistency,
- fixation,
- lymphadenopathy,
- vocal cord paralysis,
- distant metastasis
Lab/imaging:
- elevated calcitonin,
- cold nodule,
- solid lesion on ultrasound
Levothyroxine therapy: no regression
Three things to look out for about the nodule that might mean malignancy?
Fine, irregular and fixed
Features that favor a benign thyroid nodule?8
- Family history of Hashimoto’s
- Family history of benign thyroid nodule
- Symptoms of hypothyroidism or hyperthyroidism
- Pain or tenderness associated with nodule
- Soft, smooth, mobile
- Multinodular without prominent nodule
- “Warm nodule” on thyroid scan
- Simple cyst on ultrasound
Thyroid Cancer
may present how?
What lab will be normal?
How is the diagnosis made?
2
May present as painless swelling in the region of the thyroid
Thyroid function tests are usually normal
Diagnosis is made by
- fine needle aspiration cytology
- Radioactive iodine scanning usually shows malignancies to be hypofunctioning (cold)
Whats the 4 types of thyroid cancers and what are the two most common?
- Papillary – (75% to 85% of cases)
- Follicular – (10% to 20% of cases)
- Medullary – (5% of cases)
- Anaplastic – (less than 5% of cases)
Predisposing factors for thyroid cancer?
3
- Familial medullary carcinomas occur in MENII (multiple endocrine neoplasia type 2)
- exposure to ionizing radiation
- preexisting thyroid disease
Papillary Carcinoma
is often associated with what?
Describe the tumor? 2
Symptoms?
Physical Exam findings? 2
Labs to check?
Prognosis?
Treatment? 3
previous exposure to ionizing radiation
Well-differentiated, slow-growing
Hx- Mostly asymptomatic.
PE-
- Painless neck mass or
- metastatic disease to cervical lymph nodes
Labs- Thyroglobulin levels are elevated
Prognosis-10 year survival rate up to 85%
Treatment-
- Thyroidectomy in conjunction with
- radioactive iodine
- Lifetime levothyroxine
Follicular carcinoma:
Describe its growth?
Where does it spread and how?
3 places
2 modes of movement
Prognosis depends on? 2
Treatment? 3
Slow growing
- Spreads to regional nodes
- Hematogenous spread to lung or bone
Prognosis depends on
- degree of vascular invasion and
- metastases
Treatment-
- Thyroidectomy in conjunction with
- radioactive iodine
- Lifetime levothyroxine
Medullary Carcinoma:
Where does this cancer occur?
Often presents how?
What is a unique tumor marker for medullary carcinoma?
Can sometimes be part of what syndrome?
Treatment?
Occurs in the C-cells in thyroid
Often presents as a nodule in the upper half of the thyroid gland
Calcitonin is a unique tumor marker for medullary CA, although they remain eucalcimic
Is sometimes part of the MEN syndrome
Treatment is surgical removal
Hurthle Cell Carcinoma is usually classified how?
Treatment?
Usually classified as follicular thyroid cancer
Cell has a distinctive look under the microscope
Treatment is surgical removal
