Thyroid Thyroid Thyroid

Front 1

MIT + DIT = T3
DIT + DIT = T4 (thyroxine)

The molar ratio of T4:T3 is _____ within the thyroid gland.

Back 1

15:1

Front 2

Following their release into the circulation, T4 and T3 are instantaneously and almost completely bound to plasma binding proteins ______, _____ and _____. (99.7% bound)

Back 2

TBG (thyroxine-binding globulin), transthyretin (TTR), and albumin

It is the free hormone that is available to tissues and is responsible for the metabolic actions of thyroid hormone. Bound hormone appears to act primarily as a metabolically inert reservoir.

Front 3

Three means of thyroid metabolism occurs. What are they?

Back 3

Deoidination, biliary excretion, deamination

Front 4

What is the "problem" with Total T4 concentration measurements?

Back 4

It measures both the protein bound and free T4 in the serum. Thus, if TBG is increased or decreased, Total T4 (T4) will just be increased and decreased, respectively though the Free T4 can be the same amount in both events.

Reasons for increased TBG: pregnancy, estrogens, acute hepatitis, acute intermittent porphyria, drugs, genetics

Front 5

The total T3 concentration is a good test for [ hypothyroidism / hyperthyroidism ].

Back 5

hyperthyroidism

Front 6

What two tests , when coupled, can provide a highly accurate indirect estimate of the Free T4 concentration?
A. T4
B. T3
C. T3RU
D. TSH concentration

Back 6

A. T4
C. T3RU

Front 7

True or False:
TSH concentration test is an appropriate indicator of primary hypothyroidism but will miss the appropriate diagnosis in patients iwth secondary hypothyroidism.

Back 7

True

Front 8

Total T3 is
A. the most sensitive indicator of primary hypothyroidism
B. useful in diagnosing hyperthyroidism
C. is calculated from the TR3U coupled with the T4

Back 8

B. useful in diagnosing hyperthyroidism

The most sensitive indicator of primary hypothyroidsm is TSH concentration.

The Free Thyroxine Index is an indirect estimate of the free T4 concentrate calculated from the TR3U coupled with T4.

Front 9

The most common cause of hyperthyroidism is

A. Drug induces thyrotoxicosis
B. Exogenous thyroid hormone
C. Graves' disease
D. Toxic multinodular goiter
E. TSH secreting tumor

Back 9

C. Graves' disease

all others are also possible causes of hyperthyroidism

Front 10

Name some causes of hyperthyroidism. (10)

Back 10

GRAVES' DISEASE
Toxic multinodular goiter
Toxic uninodular goiter (adenoma)
Subacute thyroiditis
Exogenous thyroid hormone (iatrogenic or factitious)
Drug-induced thyrotoxicosis
TSH-secreting pituitary tumor
Struma ovarii
Metastatic follicular thyroid cancer

Front 11

Which of the following is NOT associated with Graves' disease?
A. Higher female:male ratio
B. increased incidence of other autoimmune disorfers in family members
C. HLA-DR3 is associated with increased susceptibility
D. symptoms include cold intolerance, nervousness, increased perspiration, palpitations, fatigue

Back 11

D. symptoms include HEAT (not cold!) intolerance, nervousness, increased perspiration, palpitations, fatigue

Front 12

What are some signs and symptoms of hyperthyroidism?

Back 12

SYMPTOMS: nervousness, heat intolerance, increased perspiration, palpitations, fatigue, weakness, weight loss, increased appetite, hyperdefecation, menstrual irregularities

SIGNS: tachycardia, atrial fibrilation, weidened pulse pressure, warm, moist, smooth skin, lid retraction and lid lag, exopthalmos, goiter, thyroid bruit, tremor, hyperkinesis, muscle wasting

Front 13

The type of goiter in a hyperthyroid patient details probable causes. Match each group with their description.

1. Graves, TSH producing tumors, trophoblastic tumors
2. subacute thyroiditis
3. benign thyroid neoplasms
4. exogenous thyroid hormone ingestion, struma ovarii

Absence of goiter, diffuse thyroid enlargement, nodular thyroid enlargement, thyroid tenderness with a goiter

Back 13

1. DIFFUSE THYROID ENLARGEMENT: Graves, TSH producing tumors, trophoblastic tumors
2. THROID TENDERNESS WITH GOITER: subacute thyroiditis
3. NODULAR THYROID ENLARGEMENT: benign thyroid neoplasms
4. ABSENCE OF GOITER: exogenous thyroid hormone ingestion, struma ovarii

Front 14

The hyperthyroid patient without Graves' disease has few eye symptoms such as what 2 symptoms?

Back 14

upper lid retraction ("bright eyed look") and lid lag

With Graves: eye irritation, excessive lacrimation, photophobia, diplopia, decreased visual acuity, proptosis, extraocular muscle dysfunction

Front 15

_________ is a systemic autoimmune disorder characterized by hyperthyroidism, diffuse goiter, extrathyroidal manifestations involving eyes, skin and digits.

Back 15

Graves' dz

Front 16

The autoantibody found in individuals with Graves' dz is called _______________.

Back 16

thyrotropin receptor antibody (TRAb),
thyroid stimulating antibody (TSAb)

Front 17

There are three basic approaches to the treatment of hyperthyroidism: ablative (surgery and radioactive iodine), non-ablative (antithyroid drugs), symptomatic (beta-blockers). Which of the following DO require thyroid ablation and which DO NOT?
A. Exogenous hyperthyroidism
B. Graves' dz
C. Toxic adenoma
D. Toxic multinodular goiter
E. Subacute thyroiditis

Back 17

DO NOT require ablation:
A. Exogenous hyperthyroidism
B. Graves' dz
E. Subacute thyroiditis

DO require ablation:
C. Toxic adenoma
D. Toxic multinodular goiter

Front 18

Antithyroid drugs propylthiouracil and methimazole
A. both inhibit T4 to T3 conversion
B. have the potential of hepatitis as side effect
C. are both indicated in treatment of thyroid storms
D. are both safe for pregnant women to use
E. inhibit thyroid hormone synthesis

Back 18

E. inhibit thyroid hormone synthesis

Only PTU : inhibits T4 to T3 conversion, has SE of hepatitis, is indicated in treatment of thyroid storms and is indicated in treatment of pregnant women in first trimester

Front 19

What is FALSE of radioactive iodine treatment for hyperthyroidism?
A. most common complication is hypothyroidism
B. contraindicated in pregnancy
C. can exacerbate opthalmopathy
D. increases risk of other cancers

Back 19

D. increases risk of other cancers

Apparently there is no evidence that RAI treatmetn for hyperthyroidism: causes leukemia, thyroid cancer, increases risk fo other cancers, and abnormalities in offspring, or impacts fertility

Front 20

Which of the following is FALSE regarding treatment modalities for hyperthyroidism?
A. Beta blockers are useful as adjuncts to other forms of therapy but should NOT be considered as a primary and solitary treatment option
B. Pregnant women and children should receive antithyroid drugs as initial therapy
C. Most patients over 40 y/o should receive radioactive iodine
E. None of the available therapies address the fundamental immunologic abnormality in patients with Graves' dz
F. None are false.

Back 20

F. None are false.

Front 21

What is a thyroid storm? Why does it occur? What are the symptoms? How is it treated?

Back 21

Uncommon, life-threatening condition in patients with previously unrecognized or inadequately treated hyperthyroidism. Precipitating factors include medical stressors such as surgery, obstetrical delivery, infections or other illness. Clinical features: fever, delerium, exaggerated thyrotoxicosis, CHF and rapid atrial fibrillation.

Agressive therapy is warrented with: antithyroid drug PTU (propylthioluracil), iodides, beta-blockers, glucocorticoids, and supportive care.

Front 22

The most common cause of hypothyroidism is autoimmune thyroidtitis, otherwise called _______________.

Back 22

Hashimoto's dz

Front 23

What are common causes of hypothyroidism? (4)

Back 23

Autoimmune thyroiditis (aka Hashimoto's dz), effect of hyperthyroid treatment overshoot, idiopathic, iodine deficiency (not in US)

Front 24

What are some clinical signs and symptoms of hypothyroidism?

Back 24

SYMPTOMS: weakness, sleepiness, mental slowness, muscle aches, stiffness, cold intolerance, hoarseness, weight gain, constipation, decreased sewating, menorrhagia

SIGNS: dry, cool skin, puffy eyelids and face, alopecia (coarse brittle hair), thick tongue, slow speech, hoarseness, bradycardia, swelling of hands and feet, memory impairment, delayed DTR relaxation, slow movements

Front 25

The term "myxedema" is used in association with [ hypothyroidism / hyperthyroidism ]. What does it refer to?

Back 25

hypothyroidism, refers to accumulation of hydrophilic mucopolyssaccharides in subcutaneous tissues which is responsible for the facial puffiness and swelling in peripheral tissues that can be a sign in some patients. Know that it is a clinical manifestation of hypothyroidism found only in more severe cases.

Front 26

What tests do you do for hypothyroidism?

Back 26

Serum TSH is good for primary hypothyroidism. To diagnose secondary and tertiary hypothyroidism, a free T4 determination is necessary.

Front 27

Which is the appropriate therapy for hypothyroidism in the majority of patients?
A. l-thyroxine (T4)
B. l-triiodothyronine (T3)
C. animal thyroid extracts
D. T4/T3 combinations

Back 27

A. l-thyroxine (T4) = > levothyroxine!

Reasonable estimate for dosing is 1.65 micrograms/kg body weight. Dosing decreases with increasing age.

Front 28

You plan to give a patient levothyroxine. Reasonable estimate for dosing is ______ micrograms/kg body weight. Dosing decreases with increasing age.

Back 28

1.65

Front 29

Cretinism is a condition due to neonatal [ hyperthryoidism / hypothyroidism ].

Back 29

hypothyroidism! Features are: mental retardation, short stature, characeristic puffiness of face and hands. Treatment with thyroid hormone before three months of age can result in normal intellectual development in 85% of cases.

Front 30

__________ is the end stage of untreated hypothyroidism. It is characterized by progressive weakness, altered mental status, hypothermia, hypoventilation, hypotension, hypoglycemia, hyponatremia. Even with aggressive treatment, mortality rates are not good.

Back 30

Myxedema coma

Front 31

Which thyroiditis does this describe:
rare, due to bacterial or fungal infection. Clinical manifestations include fever, sweats, tachycardia, pain and tenderness in lower anterior neck, local arythema and warmth. Normal thyroid function tests. treat with parenteral antibiotics and abcess drainage.
A. Acute thyroidtis
B. Subacute granulomatous (de Quervain's) thyroiditis
C. Subacute Lymphocytic ("Painless") Thyroiditis
D. Invasive FIbrous (Riedel's) Thyroiditis
E. Chronic Lymphocytic (Hashimoto's, Autoimmune) Thyroiditis

Back 31

A. Acute thyroidtis

Front 32

Which thyroiditis is described: probable viral etiology, anterior neck pain radiating to ears, malaise, fever. Thyroid moderately enlarged, tender, often asymmetric. Signs and symptoms of mild hyperthyroidism. Normal WBC, elevated SED rate, decreased RAI uptake.

A. Acute thyroidtis
B. Subacute granulomatous (de Quervain's) thyroiditis
C. Subacute Lymphocytic ("Painless") Thyroiditis
D. Invasive FIbrous (Riedel's) Thyroiditis
E. Chronic Lymphocytic (Hashimoto's, Autoimmune) Thyroiditis

Back 32

B. Subacute granulomatous (de Quervain's) thyroiditis

Front 33

Which thyroiditis is described: unknown etiology, mild hyperthyroidism, thyroid mildly to moderately enlarged, firm, non-tender. Elevated TFT's, low RAI uptake, normal SED. Occurs commonly in postpartum period.

A. Acute thyroidtis
B. Subacute granulomatous (de Quervain's) thyroiditis
C. Subacute Lymphocytic ("Painless") Thyroiditis
D. Invasive FIbrous (Riedel's) Thyroiditis
E. Chronic Lymphocytic (Hashimoto's, Autoimmune) Thyroiditis

Back 33

C. Subacute Lymphocytic ("Painless") Thyroiditis

Front 34

What is the difference between a "toxic" and "non-toxic" goiter?

Back 34

Toxic refers to the goiter being hyperthyroid. Nontoxic refers to the goiter being euthyroid or hypothyroid.

Front 35

Clinical presentaiton of a goiter can include what? (8)

Back 35

- symptoms of hyper or hypothyroidism
- asymptomatic thyroid enlargemnet
- sensation of fullness or tightness in neck
- dysphagia
- respiratory stridor when trachea is compressed (rare)
- hoarseness
- pain and tenderness
- superior vena cava syndrome

Front 36

Diagnostic workup for goiters include:
A. thyroid function tests, thyroid antibody studies for suspected Hashimoto's dz, biopsy
B. thyroid function tests, if TSH is suppressed then RAI scan, if normal or high, then thyroid ultrasound with guided FNA

Back 36

. thyroid function tests, thyroid antibody studies for suspected Hashimoto's dz, biopsy

the other choice is the workup fora solitary thyroid nodule

Front 37

What are some factors suggesting malignancy of a thyroid nodule?

Back 37

HISTORY: age < 20, >60. Male gender, hx of neck irradiation, recent change in size, hoarseness, dysphasia, family history of medullary thyroid cancer (as in MEN2)

PHYSICAL EXAM: hardness, fixation to surrounding tissues, cervical adenopathy, vocal cord paralysis, distant metasteses

Front 38

True or False:
Patients with multiple thyroid nodules have the same risk of malignancy as those with solitary nodules.

Back 38

TRUE

Front 39

What is FALSE?
A. Thyroid nodules are common
B. Thyroid cancer is uncommon
C. Death from thyroid cancer is rare
D. All patients not going to surgery need careful long term follow up due to FNA false negative rate of 3%
E. all are true

Back 39

E. all are true