Toxic Nodular Goiter

Question 1

is TNG the most common cause of hyperthyroidism?

Answer 1

no, -it is 15-30% of hyperthyroid in US (2nd to grave’s)

Question 2

In poor iodine diet areas, TNG is responsible for what percentage of hyperthyroidism

Answer 2

58%

Question 3

What is the most common cause of hyperthyroidism in elderly and low dietary iodine

Answer 3

Toxic Nodular Goiter

Question 4

is TNG more common in males or females?

Answer 4

females

F>M F5-7%, M1-2%

Question 5

usual age of TNG diagnosis

Answer 5

Most >50 years old- lot of time has to do with mutation rate. You can have benign nodules and then overtime they can mutate and become functional- so in older age it can happen

Question 6

Thyrotoxicosis occurs often after longstanding asymptomatic goiter once nodules become autonomous- peaks in what age?

Answer 6

50’s & 60’s

Question 7

Symptoms of TNG

Answer 7

• Can be Asymptomatic
• Hyperthyroid related: Heat intolerance, palpitations, tremor, weight loss, ↑ amount of bowel movements
• Compressive effects: dyspnea, hoarseness, dysphagia, (SVC syndrome- pt will have head edema)

Question 8

Physical Exam of TNG

Answer 8

• Tachycardia
• Hyperkinesis
• Moist skin
• Tremor
• Proximal muscle weakness- over time can have motor end plate damage which can result in muscle weakness and myopothy
• increased DTRs (deep tendon reflexes)
• Variable size of thyroid gland/nodules- size doesn’t translate with increase in symptoms
• +/-hoarseness, +/-tracheal deviation
• No ophthalmopathy, acropachy, pretibial myxedema! These are only in grave’s.

Question 9

if there is phthalmopathy, acropachy, pretibial myxedema, could the patient have Toxic Nodular Goiter?

Answer 9

• No ophthalmopathy, acropachy, pretibial myxedema! These are only in grave’s.

Question 10

Toxic Nodular Goiter etiology

Answer 10

• Related to iodine insufficiency- especially multinodular goiters, single adenomas tend to be due to mutations.
• Deficiency → low T4- because thyroid needs iodine to produce T4, inducing hyperplasia to compensate
• ↑cell replication increases risk of somatic mutations of TSH receptors, cell clone replication causing nodules

Question 11

Toxic Nodular Goiter Labs

Answer 11

• TSH low, T4/T3 elevated (similar to graves- but can run autoantibodies to graves and can tell difference between the two)
• If isolated T4 elevation- could be due to medications that reduce conversion of T4 to T3: propranolol, corticosteroids, radiocontrast, amiodarone)- remember T4 is precursor to T3
• Subclinical hyperthyroidism: low TSH, normal T4/T3 levels= pts are typically asymptomatic

Question 12

Toxic Nodular Goiter Imaging

Answer 12

Nuclear scintigraphy (iodine uptake imaging)

• Grave’s: homogenous diffuse uptake
• Tyroiditis: low uptake
• TNG: usually patchy uptake
• Can also show substernal extension of the thyroid gland- with uptake imaging you can pick this up

If compressive symptoms: CT, don’t put this off- do this quickly especially if airway compression

Question 13

would Cold nodules or hot nodules on Nuclear scintigraphy be concerning?

Answer 13

cold nodules

Question 14

Toxic Nodular Goiter will look like what in Nuclear scintigraphy?

Answer 14

very patchy because nodules in different places

Question 15

Why are old nodules on Nuclear scintigraphy concerning?

Answer 15

sign of malignancy

Question 16

would you do fine needle aspiration on a hot nodule?

Answer 16

FNA not usually needed for “HOT” nodule (autonomously functioning nodule)- risk is low malignancy

Question 17

would you do fine needle aspiration on a cold nodule?

Answer 17

yes

Question 18

TNG treatment

Answer 18

Surgery or Radioactive iodine-requires definitive treatment

Question 19

if pt has compressive symptoms then need to do _______.

Answer 19

surgery

Question 20

Complications from Radioactive Iodine

Answer 20

• Less occurrence of Hypothyroidism than Grave’s: only 10-20%
• Could get radiation induced thyroiditis (rare)
• Thyroid storm, very rare (from rapidly enlarging goiter)- pretreat with antithyroids
• Role of anti-thyroids/BB: short courses to get patient euthyroid before radiation/surgery, after radiation while thyrotoxic until full response from radiation
• not as immediate of a response as surgery, takes a little time

Question 21

Indications for surgery in toxic nodular goiter

Answer 21

o	Young
o	Large nodules
o	Compressive symptoms
o	Non-functioning/suspicious nodules
o	Pregnant
o	Radiation failure
-	Total or near total cure 90% (rapid relief)
-	Recurrence less likely than in subtotal- total thyroidectomy will have less recurrence rate than subtotal.

Question 22

Surgery Complications in toxic nodular goiter

Answer 22

• Hypothyroid
• Vocal cord paralysis
• Hypoparathyroidism
• Post op bleed- every surgery has this risk
• Infection- every surgery has this risk

Question 23

toxic nodular goiter patient care information

Answer 23

• Radiation may take 10 weeks to achieve clinical response
• Levothyroxine started after thyroidectomy , re-evalaluation after 4-6 weeks. (Subtotal thyroidectomy doesn’t necessarily need it)
• Subclinical hyperthyroid checked biochemically every 6 months- go through ROS to make sure there isn’t any thyroid symptoms

Question 24

toxic nodular goiter prognosis

Answer 24

• Treated= good
• Untreated=much worse
• Leads to Osteoporosis, dysrhythmias, HF, death

Question 25

In toxic nodular goiter, autonomously functioning thyroid nodules result in ______.

Answer 25

hyperthyroidism