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Endocrine and Reproductive Systems > CM- Thyroid Disease > Flashcards

CM- Thyroid Disease Flashcards

1
Q

Describe the steps in the examination of the thyroid. What are the characteristics of a normal thyroid?

A

Normal thyroid is anterior to thyroid cartilage and weighs about 20g

Examination:

  1. have patient face light and extend neck
  2. have the patient take a sip of water and swallow

[normal thyroid should NOT be visible even when the patient is swallowing. Enlarged thyroid of 40g or more will be visible when swallowing and will move up and down with the trachea]

Palpation:

  1. use fingertips either facing the patient or behind the patient to detect minor degrees of thyroid enlargement
  2. have patient tilt head to the side to relax SCM and attempt to palpate the lobe with swallowing

[normal thyroid only the isthmus is palpated. lateral lobes should be flat on the thyroid cartilage and not felt by your fingers when the patient swallows]

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2
Q

A patient presents with a moderate feeling of fullness in the neck. They recently started having a sensation of difficulty swallowing, pain on swallowing, cough, wheezing and stridor. When they are speaking to you, they sound very hoarse.

What are these symptoms likely caused by?
On physical exam, what 4 things should you be looking for?

A

This is symptomatic of a goiter compressing adjacent structures in the neck [mass effect].

On physical exam, you want to be looking for:

  1. size of thyroid lobes and isthmus
  2. consistency [soft, firm ,rock hard]
  3. isolated or multiple nodules
  4. presence or absence of tenderness/pain
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3
Q

When a thyroid is compressing the laryngeal nerve, what are you immediately suspicious of?

A

Malignancy is more likely to compress the recurrent laryngeal nerve.

[benign processes can too, but you want to rule out malignancy]

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4
Q

You are evaluating thyromegaly and measure the TSH. It is in the normal range [0.4-4.5]. What are the 5 etiologies that can cause this?

A

Goiter with normal TSH = euthyroidism

  1. idiopathic
  2. Hashimoto’s thyroiditis [get anti-TPO levels]
  3. iodine deficiency
  4. multinodular goiter
  5. malignancy
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5
Q

You are evaluating thyromegaly and measure TSH. It is high [>4.5]. What is the next step?

A

Measure FT4.

  1. high TSH, low FT4 = hypothyroidism
  2. high TSH, normal FT4 = subclinical hypothyroidism
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6
Q

You are evaluating thyromegaly and measure TSH. It is low [<0.4]. What is the next step?

A

Measure FT4.

  1. low TSH, high FT4 = hyperthyroidism
  2. low TSH, normal FT4–> measure T3
  3. Low TSH, normal T3 = subclinical hyperthyroidism
  4. low TSH, high T3 = hyperthyroidism
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7
Q

What is the DDx for euthyroid goiter? (5)

A
  1. idiopathic
  2. iodine deficiency
  3. Hashimoto’s thyroiditis
  4. multinodular goiter
  5. malignancy
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8
Q

What is the DDx for hyperthyroid goiter? (4)

A
  1. Graves - diffusely enlarged
  2. toxic adenoma- single nodule
  3. toxic multinodular goiter - multiple nodules
  4. Early Hashimoto’s - diffusely enlarged
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9
Q

What is the DDx for a hypothyroid goiter? (1)

A

Hashimoto’s disease- chronic lymphocytic thyroiditis

[it can be euthyroid or hypothyroid]

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10
Q

On physical examination, you discover a bilateral goiter. Thyroid function is normal. What are the 2 possibilities?
What test can distinguish one from the other?

A

It could be a euthyroid goiter or Hashimoto’s thyroiditis.

Anti-TPO antibody titer can be obtained to show it is Hashimoto’s.

Discovering that it is Hashimoto does not change initial treatment, but it does let the doctor know to follow this patient more closely because they can progress to hypothyroid.

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11
Q

On physical examination, you note a dominant nodule. You want to see if it extends into the retrosternum. What imaging should you use?

A

Xray

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12
Q

On physical exam you node a dominant nodule. You want to see the degree of compression on adjacent structures. What test do you use?

A

CT, esophogram, PFTs

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13
Q

On physical exam you note a signal thyroid nodule. You are curious if there are more. What imaging technique should be used?

A

US can tell us:

  1. size of goiter or nodule
  2. presence of multiple nodules
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14
Q

When is a radioactive iodine uptake scan (RAIU scan) useful?

A

Only in the setting of hyperthyroidism

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15
Q

A patient comes in with a multinodular goiter. Why should you not waste time/money doing a RAIU scan?

A

Multinodular goiters have areas of euthyroidism and hypothyroidism.

RAIU is only used in the setting of hyperthyroidism

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16
Q

A thyroid you are examining is asymmetric and enlarged and there is a clinically dominant nodule. What test should be done?

A

FNA of the enlargement

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17
Q

What are the 2 choices for goiter therapy?

A
  1. surgery- if size is so large it impedes on esophagus

2. observation

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18
Q

What 4 factors increase your concern for malignancy in a solitary thyroid nodule?

A
  1. young age
  2. family history
  3. past radiation exposure
  4. rapidly growing nodule
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19
Q

You discover a solitary thyroid nodule on exam. You check TSH and it is low. You check FT4 and it is high. What should you be considering?
What test/imaging technique is useful for diagnosis?

A

Hyperthyroid from a toxic nodule

If hyperthyroid, a nuclear scan can determine if the nodule is hyperfunctioning

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20
Q

You discover a solitary thyroid nodule on exam. TSH is normal.
What tests should you do next?

A
  1. US to determine if it is one nodule in a multinodular goiter and to see:
    -increased vasculature
    - irregular margins
    - calcifications
    which are all signs of malignancy.

[regardless, if it is the dominant nodule, you would still do the following]

  1. FNA is necessary for a solitary euthyroid nodule
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21
Q

If a single thyroid nodule is > 1cm, or if it is less than 1cm but with a family history and risk factors, than what should ALWAYS be performed?

A

FNA

22
Q

What are the 5 morphologies that can be seen on a FNA biopsy?

A
  1. Benign (50-60%) - macrofollicular, adenomatoid/hyperplastic nodules, colloid adenomas, nodular goiter, Hashimotos
  2. Follicular lesion with atypia of undetermined significance [mixed macro/microfollicular]
  3. Follicular neoplasm - microfollicular nodules including Hurthle cell lesions
  4. suspicion for malignancy
  5. Clearly malignant (5-10%)
23
Q

What is therapy for single thyroid nodules?

A

If benign –> watchful waiting with serial US to monitor growth OR hormone suppression

If malignant–> surgery followed by radioactive iodine

24
Q

A 30 year old woman presents with:

  1. weakness/fatigue
  2. gradual weight gain
  3. coldness
  4. heavy period
  5. dry skin
  6. bradycardia
  7. facial puffiness
  8. slow DTR

She has a symmetrical granular firm thyroid 2x normal size. TSH was 28 [SUPER high].
What is this presentation most consistent with?

A

Hypothyroidism - probably Hashimoto thyroiditis

25
Q

The clinical manifestations of hypothyroidism vary with what 2 things?

A
  1. severity of the thyroid hormone deficiency

2. rate of decline of thyroid function

26
Q

What are symptoms of hypothyroidism?

What are the signs noted on PE?

A

Symptoms: weight gain, fatigue, menorrhagia, constipation, dry skin, non-pitting edema, cold intolerance, shortness of breath

Signs: delayed DTR, coarse dry skin, bradycardia, puffy face/periorbital edema, diastolic hypertension, ascites, pericardial effusion

27
Q

What are the 2 medical principles underlying the clinical manifestations of hypothyroidism?

A
  1. slowing of metabolic processes/energy expenditure–> cold intolerance, fatigue, weight gain, slow DTR, slow speech/movement
  2. building up of matrix substance in the tissue due to deposition of glycosaminoglycans and hyaluronic acid –>dry skin, non-pitting edema, hoarseness, periorbital swelling
28
Q

What causes the cool dry skin of hypothyroidism?

A

decreased blood flow and reduced sweating

29
Q

What contributes to the hypertension that may develop with hypothyroidism?
What contributes to the fatigue, DOA and diminished exercise tolerance?

A

hypertension-increased PVR

fatigue, DOA, exercise intolerance –> decreased respiratory muscle function

30
Q

A patient has been gaining weight and feeling generally sluggish. They have bilateral carpal tunnel syndrome. What is the problem and why do they have carpal tunnel?

A

Hypothyroidism and the depositioin of GAGs and hyaluronic acid lead to entrapment of nerves in the wrist

31
Q 
A person has:
High TSH, low T3/T4
decreases SHBG [sex hormone binding globulin]
hyponatremia
hyperlipidemia
hypercarotonemia [pigmented skin]

What is the likely problem?

A

Hypothyroidism

32
Q

What lab results are associated with hypothyroidism?

A
  1. high TSH, low T3/4
  2. low SHBG
  3. hyponatremia
  4. hyperlipidemia
  5. hypercarotenemia
33
Q

In most cases, a high TSH with a low free T4 indicates _________________.
In a patient with no symptoms, a high TSH and normal T4, a physician is suspicious of ________________.

A

High TSH, low T4 = primary hypothyroidism

High TSH, normal FT4, no symptoms = subclinical hypothyroidism

34
Q

What are the 3 major causes of hypothyroidism in the US?

A
  1. Hashimoto [chronic autoimmune thyroiditis]
  2. iatrogenic [radioiodine treatment, thyroidectomy, lithium, amiodarone]
  3. transient hypothyroidism from thyroiditis [lymphoctyic/painless, granulomatous/painful, postpartum]
35
Q

Describe the process of transient hypothyroidism from thyroiditis.
How long does each stage usually last?

A
  1. inciting factor initiations thyroid inflammation damaging follicles and activating proteolysis
  2. Unregulated release of T3 and T4 into circulation results in hyperthyroidism which lasts until the stores are exhausted.
  3. new hormone synthesis ceases because of damaged follicles and feedback from low TSH due to the release of a large store of T3/4
  4. Inflammation subsides the thyroid follicle regenerates and T3/4 synthesis resumes
  5. the patient is hypothyroid until the stores are suggicient to regain normal homeostasis

[each stage lasts 2-8 weeks except transient euthyroidism on the way to hypo]

36
Q

What is therapy for hypothyroidism?

A

Hormone Replacement Therapy [HRT]

Usually with thyroxine [7-8 day half life so takes weeks to get to steady state]

37
Q

An elderly individual recently had an MI. Now they are presenting with hypothermia, hypoxia due to decreased respiratory drive, and decreased cardiac function.
What is this presentation? What is treatment?

A

This is myxedema coma -
when a hypothyroid patient [usually elderly] is exposed to a precipitating event [MI, infection, trauma, drugs] they can present with:
1. hypoxia due to decreased resp. drive
2. hypothermia
3. decreased cardiac function due to hypothyroidism + secondary pericardial effusion

Treat with: IV thyroid hormone replacement and try to figure out the precipitating factor

38
Q

A 22 year old woman is feeling anxious, and has tremors and palpitations. She has lost 10lbs without changing her diet.
She has increased stools, but absent menses.
Her HR is “irregularly irregular” and fast.
Her eyes are bugging out and she has a palpably diffusely enlarged bilateral goiter. When you listen to it, it has a bruit.
She also has myxedema on the fronts of her shins.

TSH is below measurement threshold and T3/T4 is sky-high.
What is the problem?

A

She is hyperthyroid and based on symptoms of:

  1. exopthalmus
  2. bilateral diffuse enlargement with bruit
  3. myxedema on shins

We know that it is Graves

39
Q

What is the most characteristic symptoms of hyperthyroidism?

A

Weight loss despite normal food intake

40
Q

Why is menses absent and gynecomastia present in people with hyperthyroidism?

A

Hyperthyroidism increases the level of SHBG so:

  1. estrogen/progesterone is irregular
  2. testosterone is not getting to the testes
41
Q

What causes the cardiovascular problems associated with Graves/hyperthyroidism?

A
  1. T3 directly stimulates cardiac ionotropy and chronotropy.
  2. increased thermogenesis in the tissues leads to decreased systemic vascular resistance resulting in increased cardiac contractility
42
Q

In hyperthyroidism what is the physiologic cause of:

  1. warm skin
  2. sweating
  3. pigmentation
  4. increased CO and SOB
  5. weight loss
  6. osteoporosis
A
  1. increased blood flow
  2. calorigenesis
  3. metabolized cortisol –> increased ACTH–> increased MSH
  4. increased peripheral oxygen demand
  5. metabolic increase
  6. bone turnover
43
Q

What are the non-metabolic changes related to thyroid hormone increase?

A
  1. increases adrenergic state leading to:
    - increased HR and contractility
    - retracted eyelids
    - arrythmia/tremor
  2. increases LDL receptors in the liver
  3. raises SHBG
    - women :low estrodiol, high LH, oligomenorrhea
    - men: increased bound testosterone, normal free resulting in conversion of testosterone to estrodiol peripherally
44
Q

What causes exopthalmus in Graves?

What causes myxedema in the pretibial areas?

A

EYES- Inflammation and accumulation of hyluronic acid in the extra-ocular muscles and retro-orbital connective tissue –> protrusion of globes forward and double vision

LEGS- accumulation of GAGs in the dermis

45
Q

What are the 5 things on the differential for hyperthyroidism?

A
  1. Graves [young women]
  2. Early Hashimoto
  3. de Quervain thyroiditis [viral/granulamatous/painful]
  4. Toxic adenoma [single nodule, middle aged women]
  5. toxic multinodular goiter [middle aged women]
46
Q

What is the likely cause of hyperthyroidism if the goiter is:

  1. diffuse, soft with a bruit
  2. single palpable nodule
  3. painful and tender
  4. multiple nodules
  5. painless and small
A
  1. Graves
  2. toxic adenoma
  3. deQuervain thyroiditis
  4. toxic multinodular goiter
  5. early hashimotos
47
Q

In what hyperthyroid presentation would you see:
low TSH
high end of normal T4
super high T3?

A

Graves- T3 levels are increased earlier and to a greater extend than T4

“T3 toxicosis”

48
Q

A patient presents with hyperthyroid symptoms but the TSH is normal/elevated. What are 2 possible causes?

A
  1. TSH-secreting adenoma of the pituitary

2. selective pituitary resistance to thyroid hormone

49
Q

What imaging modality is used if the patient is hyperthyroid?
Why?

A

RAIU because it will distinguish between:
1. conditions where the thyroid is actively making too much T3/T4 [Graves, toxic adenoma/multinodular goiter] will have high/normal RAIU with low TSH

  1. conditions where preformed T3/T4 is being released but no new is being made [thyroiditis] will have a low RAIU
50
Q

What is the effect of ingestion of iodine-containing substances on RAIU?

A

it will result in a falsely low RAIU by increasing iodide pool

51
Q 
What is therapy for:
Graves
Toxic adenoma
Toxic multinodular goiter
thyroiditis
A
  1. thionamides [PTU, methimazole], radioiodine
  2. radioiodine
  3. thionamides, radioiodine, surgery
  4. pain meds, steroids, time
52
Q

A patient with baseline hyperthyroidism experiences trauma, MI, infection. What is the concern and what symptoms are you on the lookout for?
What is treatment?

A

Thyroid storm and you want to monitor for:

  1. hyperthermia
  2. cardiac arhrythmias
  3. CNS effects [agitation, seizures, delerium]

Treatment is supportive care, identify precipitating event, aggressive treatment of hyperthroidism with:

  1. thionamides
  2. iodine
  3. b-blockers

Endocrine and Reproductive Systems (27 decks)

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