Multinodular Goiter

Question 1

Enlarged thyroid gland
Multiple nodules
Disordered growth of thyroid cells
Gradual development of fibrosis

Answer 1

Multinodular Goiter

Question 2

Patient is euthyroid

Enlarged thyroid gland with multiple nodules

Answer 2

Nontoxic MNG

Question 3

Patient is thyrotoxic

1 or more nodules producing thyroid hormone INDEPENDENT of TSH regulation

Answer 3

Toxic MNG

Question 4

Most common MNG

Answer 4

Nontoxic MNG

Question 5

Histologic characteristic of MNG

Answer 5

Disordered growth of thyroid cells

Gradual development of fibrosis

Question 6

MNG epidemiology

Prevalance

Sex

Age

Environment

Answer 6

12% adults

W>M

Increases with age

More common in iodine-DEFICIENT regions but also occur in iodine sufficiency

Question 7

Risk factors for MNG

Answer 7

Iodine deficiency
Radiation exposure
Recent exposure to iodine from contrast dyes or other sources may precipitare or exacerbate thyrotoxicosis in toxic MNG

Question 8

Pathogenesis of MNG

Answer 8

genetic
autoimmune
environmental

multifactorial

Question 9

Major difference between toxic and nontoxic MNG is

Answer 9

autonomous production of excess thyroid hormone in the toxic MNG

when toxic MNG develops, it evolves from nontoxic MNG as natural history

Question 10

Stages of nodular transformation of thyroid

Answer 10

Goitrogenic stimuli (iodine deficiency, autoimmunity, or nutritional goitrogens) 
cause diffuse thyroid hyperplasia

Question 11

Non toxic MNG signs and symptoms

Answer 11

Most are asymptomatic.

Discovered 3 ways:
Goiter with multiple nodules
Incidental finding on CT (substernal goiter)
Enlargement in neck noted by patient

Compressive symptoms in large MNG

Dysphagia (rare)

Plethora venous congestion

Horner’s syndrome

Question 12

In large goiters obstructing venous return within thoracic aperture

Facial congestion and external jugular vein obstruction when arms are raised above the head

Answer 12

Pemberton’s sign

Question 13

Signs and symptoms may suggest cancer

Answer 13

Pain (hemorrhage into nodule)
Hoarseness (laryngeal nerve involvement)
Stridor
Respiratory distress (tracheal compression)
Tracheomalacia

Question 14

PE of MNG

Answer 14

Thyroid architecture is often distorted with multiple nodules of varying size
Substernal goiters nonpalpable
PE underestimates the goiter size

Question 15

Laboratory that distinguishes nontoxic MNG from toxic MNG

Answer 15

TSH

Question 16

Imaging is indicated for MNG if

Answer 16

Verify hyperfunctioning nodules in a patient with MNG with concomitant clinical/laboratort evidence of hyperthyroidism

Evaluate degree of obstruction in large MNG

Question 17

FNA for MNG is recommended

Answer 17

Dominant or enlarging nodule with MNG
Nonfunctioning (COLD) nodules >/= 1.5 cm in diameter
Nodules found to have microcalcifications
Complex architecture on ultrasonography

Question 18

FNA should not be used on

Answer 18

Autonomous HOT/warm nodules

Question 19

Thyroid function test if nontoxic MNG

Answer 19

Normal TSH

Question 20

Thyroid function test if toxic MNG

Answer 20

TSH level is low

Normal or minimally increased FT4

Question 21

CT or MRI of the chest are indicated only when

Answer 21

Evaluating goiter anatomy
Substernal extension
Extent of tracheal compression

Question 22

Airway compromise indicates compression of tracheal diameter by how

Answer 22

70%

Question 23

Iodinated contrast agents should be administered cautiously to persons with

Answer 23

Low TSH

may precipitate underlying hyperthyroidism

consider pretreatment with antithyroid drug before contrast imaging

Question 24

Thyroid scintigraphy (iodine or technetium) should be limited to MNG patients with

Answer 24

low TSH

to verify clinical diagnosis of toxic MNG

Question 25

UTZ in MNG is useful for

Answer 25

Accurate monitoring of nodule size | Guiding FNA biopsy of suspicious nodules

Question 26

Barium swallow is indicated in MNG

Answer 26

To assess whether esophageal compression causes dysphagia

Question 27

FNA biopsy in MNG should be considered for

Answer 27

``` A dominant nodule >1-1.5cm diameter Enlarging nodule with MNG Nodules with microcalcifications Hypoechogenecity Increased vascularity Complex architecture ```

Question 28

Nontoxic MNG treatment

Answer 28

Observation if euthyroid in smal nontoxic MNG

Question 29

Treatment for nontoxic MNG is indicated if

Answer 29

Obstructive complication Large or progressively growing goiter Cosmetic concerns

Question 30

Forms of therapy for nontoxic MNG

Answer 30

Total thyroidectomy To dec size Radioiodine 132I Levothyroxine

Question 31

Treatment of toxic MNG is indicated

Answer 31

for all patients 3 forms Total thyroidectomy Radioiodine treatment Antithyroid drug therapy

Question 32

Provides most effective and rapid reduction in goiter size of all available therapies

Answer 32

Thyroidectomy Disadvantage Surgical risk in elderly person with cardiopulmonary disease Surgical complications Post-surgical HYPOthyroidism

Question 33

Gradual reduction in goiter size Safe, outpatient Can achieve 40-50% reduction of goiter size but patient may have Transient elevations of thyroid hormone levels within first 2 weeks after therapy Hypothyroidism may develop

Answer 33

Radioiodine therapy

Question 34

Started at low dose since many MNG contain autonomous regions Avoid excessive TSH supression Low efficacy Regrowth after discontinuation of therapy

Answer 34

Levothyroxine supression

Question 35

Levothyroxine can precipitate this side effect

Answer 35

Subclinical HYPERTHYROIDISM

Question 36

Hyperthyroidism following administration of iodine or iodide as dietary supplement or as iodinated contrast for medical imaging

Answer 36

Jod-Basedow effect

Question 37

Autoregulatory phenomenon whereby a large amount of ingested iodine acutely inhibits thyroid hormone synthesis (organification) as well as release within the follicular cells irrespective of the serum level of thyroid-stimulating hormone TSH

Answer 37

Wolf-Chaikoff Phenomenon | Hypo

Question 38

Toxic MNG Treatment

Answer 38

B blockers Radioiodine therapy (for areas of autonomy and dec the mass of the goiter) Thyroidectomy Antithyroid drugs (euthyroid in 4-6 weeks)

Question 39

Disadvantage of treating toxic MNG with antithyroid drugs alone

Answer 39

Therapy is lifelong because hyperthyroidism in toxic MNG does not remit spontaneously May increase size of goiter