Thyroid Pathophysiology Flashcards Preview

Endocrinology > Thyroid Pathophysiology > Flashcards

Flashcards in Thyroid Pathophysiology Deck (36)

Describe the epidemiology of hypothyroidism:

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


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

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


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

Follicular atrophy
Infiltration with lymphocytes


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

Yes, other autoimmune disorders


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

Serum level of 5


What is myxedema coma?

Which patients will exhibit myxedema coma?

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

Characterized by hypothermia and coma with 20-25% mortality


What are the clinical features myxedema coma?

What lab values would you expect?

Mental status changes : stupor, confusion, coma and hypothermia

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


How is myxedema coma managed?

Treat precipitating factors.

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


How is hypothyroidism treated?

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


What are causes of hyperthyroidism? (5)

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


What are causes of thyroiditis? (4)

What are possible courses? (3)

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)


List some clinical symptoms of hyperthyroidism

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


List some signs of hyperthyroidism

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


What is pathophysiology of Graves disease?

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


What is histology of Grave's disease?

Hyperplasia of follicular cells-- lots of colloid but it's irregular and more papillary.


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

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

Graves: Proptosis, diplopia, inflammatory changes


Describe rare symptoms of Grave's disease: dermatologic

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


How do you differentiate between causes of hyperthyroidism?

What is the normal value for the test?

Radioiodine uptake

Normal uptake is 15-35%


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

Graves: Elevated uptake
Thyroiditis: Decreased uptake


What are the treatment options for Grave's disease?

1. Antithyroid drugs
2. Radioiodine ablation
3. Surgery


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

Methimazole, PTU

AE: rash, agranulocytosis, hepatitis


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

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

AE: teratogenic, hypothyroid, worsens ophthalmopathy


When is a thyroidectomy performed (2)?

What is main side affect?

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

Hypothyroidism results.


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

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

Incidence is 1-2% with vastly decreasing mortality.


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

Really some might fuck tonight:

Restlessness, Sweating, Mental status change, fever, tachycardia


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

A goiter is an enlarged thyroid gland.

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


What is the etiology of goiters?

Multiple-- thyroiditis, cancer, nodules etc.


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

Goiter is most commonly caused by iodine deficiency.

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


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

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

Risk factors include old age, women, gender susceptibility


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

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

Benign (90%)


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

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


What factor is important in radiation and thyroid cancer?

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

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.


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

Fixation to adjacent structures
Firm nodular consistency


When do you need to do an FNA? Why?

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


How many nodules are "cold"?

What do you with cold nodules?

Cold or hypofunctioning nodules make up 90% of nodules.

You follow up with FNA


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

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

Only 1/3 have cancer.