Thyroid Pathophysiology Flashcards Preview

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Flashcards in Thyroid Pathophysiology Deck (36)
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1
Q

Describe the epidemiology of hypothyroidism:

A

10M Americans: Higher risk in women, especially as they age past 40

2
Q

What are the etiologies of hypothyroidism? Primary (4), central and transient

A

Primary: Autimmune (Hasimoto’s), thyroidectomy, dysgenesis/agenesis, defects in biosynthesis
Central: Pituitary/hypothalamic
Transient: hypothyroid phase of thyroiditis

3
Q

What do you see on pathology for lymphocytic thyroiditis (Hashimoto’s)? (2)

A

Follicular atrophy

Infiltration with lymphocytes

4
Q

Are Hashimoto’s patients more susceptible for any other diseases?

A

Yes, other autoimmune disorders

5
Q

What is the clinical significance of mild thyroid failure? Is treatment indicated?

A

Serum level of 5

6
Q

What is myxedema coma?

Which patients will exhibit myxedema coma?

A

Severe hypothyroidism seen in elderly patients with pre-existing hypothyroidism and acute illness.

Characterized by hypothermia and coma with 20-25% mortality

7
Q

What are the clinical features myxedema coma?

What lab values would you expect?

A

Mental status changes : stupor, confusion, coma and hypothermia

Labs: high FSH with low T4, total T3, hyponatremia, hypercholesterolemia, high LDH, hypoxemia

8
Q

How is myxedema coma managed?

A

Treat precipitating factors.

GIVE STEROIDS before Thyroid hormone–>supplemental thyroid hormone will increase glucocorticoid metabolism

9
Q

How is hypothyroidism treated?

A

Levothyroxine sodium (LT4)– Take one pill daily to achieve normal TSH

10
Q

What are causes of hyperthyroidism? (5)

A

Overproduction: Graves disease, toxic solitary nodule, toxic multi nodular goiter
Leakage of thyroid hormone: autoimmune thyroiditis, viral thyroiditis

11
Q

What are causes of thyroiditis? (4)

What are possible courses? (3)

A

Causes: Autoimmune, bacterial/fungal, viral, toxic

Course: Hyperthyroidism (leakage of stored thyroid hormone), return to euthyroid state, swing to transient hypothyroidism (while damaged follicular cells recover)

12
Q

List some clinical symptoms of hyperthyroidism

A

Appetite change, shortness of breath, fatigue, headache, heat intolerance, hyperactivity, increased perspiration, irritability, menstrual disturbance, nervousness, palpitations, muscle weakness, sleep disturbance, tremor, weakness, weight change

13
Q

List some signs of hyperthyroidism

A

Goiter, hyperactivity, hyperreflexia, muscle weakness, systolic hypertension, tachycardia/arrhythmia, tremor, warm/moist/smooth skin

14
Q

What is pathophysiology of Graves disease?

A

Autoimmune binding to TSH receptor in pituitary– antibody is stimulating.

15
Q

What is histology of Grave’s disease?

A

Hyperplasia of follicular cells– lots of colloid but it’s irregular and more papillary.

16
Q

Describe the ophtho symptoms of hyperthyroidism (3). Compare them to graves ophthalmopathy (3)

A

Hyperthyroidism: Lid lap, lid retraction, stare due to increased adrenergic tone to levator palpibrae

Graves: Proptosis, diplopia, inflammatory changes

17
Q

Describe rare symptoms of Grave’s disease: dermatologic

A

Dermatological: myxedema in lower leg
Acropachy: clubbing of fingers, separation of nail plate from bed

18
Q

How do you differentiate between causes of hyperthyroidism?

What is the normal value for the test?

A

Radioiodine uptake

Normal uptake is 15-35%

19
Q

What are the results of radioiodine uptake for Graves disease vs. Thyroiditis?

A

Graves: Elevated uptake
Thyroiditis: Decreased uptake

20
Q

What are the treatment options for Grave’s disease?

A
  1. Antithyroid drugs
  2. Radioiodine ablation
  3. Surgery
21
Q

What are the antithyroid drugs (2) and what are their side effects (3)?

A

Methimazole, PTU

AE: rash, agranulocytosis, hepatitis

22
Q

Describe the efficacy and side effects of radioactive iodine (3)

A

It’s an oral therapy to destroy the thyroid that takes 3-6 months.

AE: teratogenic, hypothyroid, worsens ophthalmopathy

23
Q

When is a thyroidectomy performed (2)?

What is main side affect?

A

Thyroidectomy for large toxic nodular goiters with compressive symptoms OR patients who have had severe AE with antithyroid drugs

Hypothyroidism results.

24
Q

What is a thyroid storm? Describe it’s cause, incidence and mortality

A

Thyroid storm is extreme manifestation of thyrotoxicosis– result of tissue exposure to excessive thyroid hormone.

Incidence is 1-2% with vastly decreasing mortality.

25
Q

What is the clinical manifestation of a thyroid storm? (5)

A

Really some might fuck tonight:

Restlessness, Sweating, Mental status change, fever, tachycardia

26
Q

What is a goiter? What criteria do you use to describe it? (3)

A

A goiter is an enlarged thyroid gland.

Prevalence: endemic/non-endemic
Structure: Diffuse vs. nodular
Function: Toxic or non-toxic

27
Q

What is the etiology of goiters?

A

Multiple– thyroiditis, cancer, nodules etc.

28
Q

What is most common cause of goiters? How common are they?

A

Goiter is most commonly caused by iodine deficiency.

It is in >10% population and is present in 4-7% US population

29
Q

How common are thyroid nodules? What are risk factors? (3)

A

Palpable in 6% women 1.5% men aged 30-60.

Risk factors include old age, women, gender susceptibility

30
Q

What is the differential diagnosis for thyroid nodules? What are the relative frequencies?

A

Malignant (5-10%)– papillary (75%), follicular (15%), medullary

Benign (90%)

31
Q

What are things you look for to evaluate thyroid nodules in history?

A

Neck irradiation, family history, age, gender, duration, local symptoms, presence of coexistent benign thyroid disease

32
Q

What factor is important in radiation and thyroid cancer?

How long is latency period? How long does risk last?

A

Age at irradiation– there is no increase in risk if exposed after 16-18.

Latent period is 10-20 years, but risk if lifelong following exposure.

33
Q

What are things you look for in physical exam of thyroid nodules? (3)

A

Fixation to adjacent structures
Adenopathy
Firm nodular consistency

34
Q

When do you need to do an FNA? Why?

A

If TSH is normal or high. Low TSH or “hot” nodules have low likelihood of malignancy.

35
Q

How many nodules are “cold”?

What do you with cold nodules?

A

Cold or hypofunctioning nodules make up 90% of nodules.

You follow up with FNA

36
Q

How many patients with atypical thyroid nodules receive surgery? How many of those are malignant?

A

30% of patients with atypical thyroid nodules go to surgery.

Only 1/3 have cancer.