Hypothyroid

Question 1

Hypothyroidism is almost always (primary/secondary)

Answer 1

Primary (dysfunction, failure or absence of thyroid) (95%)

Question 2

Hypothyroidism is usually seen in (men/women) and (young/old) patients

Answer 2

Women; older

Question 3

Most common causes of Hypothyroidism

Answer 3

Autoimmune (Hashimoto’s)*
Post-surgical
Radioiodine ablation
Medications (amiodarone, lithium, etc.)

*#1 in the United States

Question 4

Most common cause of Hypothyroidism in US

Answer 4

Hashimoto’s Thyroiditis (autoimmune)

Question 5

How does amiodarone cause Hypothyroidism

Answer 5

Wolff-Chaikoff Effect (when large amounts of iodine, which amiodarone is derived from, inhibits thyroid peroxidase within the follicular cells)

Question 6

Cause of Hypothyroidism (MOST common cause in US); autoimmune destruction of Thyroid tissue; firm, non-tender enlargement of the thyroid gland; can see extensive lymphocytes, loss of colloid, Hurthle cell transformation and fibrosis on histology

Answer 6

Hashimoto’s Thyroiditis

Question 7

Histology findings for Hashimoto’s Thyroiditis

Answer 7

Extensive lymphocytes
Loss of colloid
Hurthle cell transformation
Fibrosis (late stage)

Question 8

What are the signs/symptoms of Hypothyroidism caused by?

Answer 8

Dec. metabolism and organ function

Accumulation of glycosaminoglycans (non-pitting edema)

Question 9

Signs/Symptoms of Hypothyroidism

Answer 9

Fatigue/weakness
Weight gain
Cold Intolerance*
Dec. HR
inc. BP (diastolic)
Dry skin/hair
non-pitting Edema*
Delayed reflexes*

Question 10

Why might drawing thyroid tests in critically ill patients be problematic?

Answer 10

Can falsely look like SECONDARY hypothyroidism (low TSH and T3/T4)

Question 11

Treatments for Hypothyroidism

Answer 11

Levothyroxine (synthetic form of T4)

Question 12

Synthetic form of T4 used to treat Hypothyroidism

Answer 12

Levothyroxine

Question 13

Demand for thyroid hormone increases during pregnancy, leading to what changes

Answer 13

Increased metabolism, TBG (estrogen), and urine iodide excretion

Question 14

How can hypothyroidism during pregnancy be devastating?

Answer 14

1. Affects brain development (one of 4 B’s)

2. Inc. risk of miscarriage, placental abruption, etc.

Question 15

Signs/Symptoms of Congenital Hypothyroidism (aka “cretinism”)

Answer 15

*4 P’s

Poor brain development
Protruding tongue
Pot-bellied
Puffy face

Question 16

Coma brought on by SEVERE Hypothyroidism; seen with chronic hypothyroidism after a precipitating event, such as severe illness, infection, surgery, etc.; has bradycardia, hypotension, hypothermia, hypoventilation and stupor (insensitivity)

Answer 16

Myxedema Coma

Question 17

Hashimoto’s thyroiditis is associated with increased risk of what malignancy

Answer 17

B-cell lymphoma

Question 18

TSH, T4, T3 Levels of Primary Hypothyroidism

Answer 18

High, low, low

Question 19

TSH, T4, T3 Levels of Subclinical Hypothyroidism

Answer 19

High, normal, normal

• early primary hypothyroidism

Question 20

TSH, T4, T3 Levels of Secondary Hypothyroidism

Answer 20

Low, low, low

Question 21

Substance that impair absorption of levothyroxine

Answer 21

Ca+2, Fe, multivitamins

Question 22

TSH, Total T4, free T4 of pregnant woman with normal thyroid function

Answer 22

Normal, high, normal

Question 23

TSH, Total T4, free T4 of pregnant woman with hypothyroidism

Answer 23

high, low, low

Question 24

How does hcg affect the levels of TSH and T4

Answer 24

Decrease TSH
Increase T4

*hcg acts like TSH

Question 25

Accumulation of GAGs cause what clinical features in hypothyroidism and hyperthyroidism

Answer 25

Hypothyroidism: non-pitting edema

Hyperthyroidism: dermpathy (grave’s disease)