Endocrine #2 (Thyroid Disorders)

Question 1

Explain the hypothalamus-pituitary-thyroid axis.

Describe a primary thyroid disorder. How about a secondary disorder?

Answer 1

Hypothalamus secretes TRH –> Pituitary secretes TSH –> Thyroid secretes T3 and T4

Primary: Disease in the thyroid

secondary: Disease in hypothalamus or pituitary

Question 2

MCC of Hyperthyroidism. Explain the pathophysiology of this.

Answer 2

Graves Disease

Autoimmune disease: TSH receptor antibodies target and stimulate TSH receptor leading to thyroid gland enlargement and hyperthyroidism (t3 and T4 production)

Question 3

Symptoms of hyperthyroidism

Answer 3

-Palpitations
-Heat Intolerance
-Tremors, weight gain
-Atrial fibrillation
-Ophthalmopathy: proptosis, exophthalmos, lid lag, diplopia, vision changes
-Pretibial Myxedema: swollen red patches on legs with non-pitting edema
-Warm, moist skin
-Fine Hair
-Diffusely enlarged non-tender goiter
-Hyperreflexia
-Insomnia
-Diarrhea
-Fine Tremors, Anxiety, Nervousness

Question 4

What labs are done for hyperthyroidism? What is specific for Graves Disease?

What is shown on radioactive iodine uptake scan?

Answer 4

-Decreased TSH + Increased Free T4 and T3

• • Thyroid Stimulating Immunoglobulins (TSH receptor antibodies) for Graves

-Diffuse, increased iodine uptake (active and hyper)

Question 5

Treatment for Hyperthyroidism

_____ for Symptoms

______first line for thyroid hormone synthesis

______ for ophthalmopathy

Answer 5

Beta Blockers for symptoms

Methimazole or Propylthiouracil (PTU)

Glucocorticoids

Question 6

What treatment is preferred in the first trimester and for thyroid storm?

Answer 6

PTU

Question 7

What is thyroid storm/thyrotoxicosis?

Answer 7

Potentially fatal if untreated, thyrotoxicosis after a precipitating event (surgery, trauma, infection, pregnancy, preeclampsia)

-Hyperthyroid with an event that makes it much worse

Question 8

Symptoms of thyroid storm

Answer 8

-Hyperthyroid storm + CV Dysfunction (palpitations, tachycardia, A-fib, CHF)
-High fever, Tremors
-CNS Dysfunction: delirium, psychosis, stupor, coma

Question 9

Management for thyroid storm

Answer 9

-IVF + Propanolol + IV Glucocorticoids + PTU

-Then oral or IV sodium iodide

-Cooling blankets

-Antipyretics (not Aspirin)

Question 10

What is the MCC of Hypothyroidism in the US?

What is the pathophysiology of this?

Answer 10

Hashimoto Thyroiditis

Autoimmune thyroid cell destruction by anti-thyroid peroxidase and anti-thyroglobulin

Question 11

What are other etiologies of hypothyroidism?

What is the MCC in the WORLD?

Answer 11

Amiodarone, Lithium, Alpha-Interferon

Hashimoto’s

Iodine Deficiency MCC in world

Question 12

Symptoms of hypothyroidism

Answer 12

-Decreased metabolic rate
-Cold intolerance
-Weight gain
-Dry, thick rough skin
-Loss of outer 1/3 of eyebrow
-Nonpitting edema (Myxedema)
-Fatigue, memory loss, depression
-Constipation
-Anorexia
-Bradycardia
-Galactorrhea (increased prolactin)

Question 13

What is the normal lab values for hypothyroidism?

What is specific to Hashimoto?

What is seen on radioactive iodine uptake scan?

Answer 13

Increased TSH + Decreased free T3/T4

+ Antithyroid peroxidase and/or anti-thyroglobulin antibodies

Decreased iodine uptake (inactive and slow)

Question 14

Treatment for hypothyroidism

Answer 14

-Levothyroxine (Synthetic T4)

AKA Synthroid

Question 15

Explain what myxedema coma is.

Who should you think about when thinking about this condition?

What are some other “precipitating events”

Answer 15

Extreme form of hypothyroidism with a high mortality rate

Elderly women with a long-standing history of hypothyroidism in the winter

Discontinuation of Levothyroxine, infection, CHF, etc.

Question 16

Symptoms of Myxedema Coma

Answer 16

-Severe signs of hypothyroidism + bradycardia + hypothermia + hypotension + hypoglycemia + hyponatremia

Question 17

Treatment for Myxedema Coma

Answer 17

-IV Levothyroxine + Supportive (ICU, passive warming), IV Glucocorticoids

Question 18

What are some etiologies of iatrogenic hypothyroidism?

Answer 18

-Surgery without subsequent thyroid hormone replacement
-Amiodarone
-Lithium
-Alpha-Interferon

Question 19

What is Cretinism?

What is the MCC in developing counties?

What is the MCC in developed countries?

Answer 19

Untreated congenital hypothyroidism

-Developing: lack of maternal iodine intake

-Developed: Dysgenesis of thyroid gland

Question 20

Symptoms of cretinism

Answer 20

-Mental developmental delays
-Symptoms of hypothyroidism
-Goiter symptoms: hoarseness and dyspnea
-Coarse facial features: Macroglossia, umbilical hernia, hypotonia, feeding problems, prolonged jaundice

Question 21

Treatment for Cretinism

Answer 21

Levothyroxine

Question 22

What is subclinical hypothyroidism?

Answer 22

Isolated increased TSH in patients with little or no symptoms

Question 23

What do labs show for subclinical hypothyroidism?

what is the treatment?

Answer 23

Isolated increased TSH + Normal T3/T4

Levothyroxine if TSH 10 or higher to prevent cardiovascular problems

Question 24

Euthyroid Sick Syndrome is …..

It is MC seen in those with …..

Answer 24

Abnormal thyroid function tests in patients with normal thyroid function

Sepsis, malignancies, etc.

Question 25

What unique thing is seen on diagnostics for Euthyroid Sick Syndrome?

Answer 25

Low T3 Syndrome: decreased free T3 and increased reverse T3 (inactive form of T3)

Question 26

Risk factors for a thyroid nodule

Answer 26

-Extremes of age (very young or > 60)
-History of head and neck radiation

Question 27

What is the MC type of thyroid nodule?

Answer 27

-Follicular adenoma (colloid)

Question 28

Although most thyroid nodules are asymptomatic, what symptoms CAN the patient have?

Answer 28

-Compressive symptoms: swallowing or breathing difficulty, neck/jaw/ear pain, hoarseness (recurrent laryngeal nerve impingement)

Question 29

What nerve can be compressed by a thyroid nodule?

Answer 29

Recurrent laryngeal nerve

Question 30

On physical exam, explain what a benign thyroid nodule feels/appears like?

How about a malignant nodule?

Answer 30

Benign: varied, smooth, firm, irregular, sharply outlined, discrete, painless

Malignant: rapid growth, fixed in place, no movement with swallowing, hypoechoic on US

Question 31

What is the initial test done to evaluate the nodule?

Answer 31

-Thyroid function testing

Question 32

If TSH is normal, what is indicated to further evaluate the nodule?

Answer 32

FNA with biopsy

Question 33

What test is done after thyroid function tests to determine if a FNA is needed?

Answer 33

Thyroid US

Question 34

A FNA with biopsy is performed on a thyroid nodule if it is > _____________________ or in highly suspicious nodules

Answer 34

if > 1.5 cm with normal TSH

Question 35

What can be performed if the FNA is indeterminate or low or subnormal TSH?

What results can you get with this and what does it mean?

Answer 35

Radioactive iodine uptake scan

Cold nodules (no or low iodine uptake) should be biopsied to rule out malignancy

Functioning (normal) or hot nodules have low malignancy potential

Question 36

What is the treatment for a cold nodule, if thyroid cancer suspected, or an indeterminate FNA?

Answer 36

Surgical excision

Question 37

If surgery is NOT performed for a thyroid nodule, when should you get an US?

Answer 37

Observation + follow up US every 6-12 months to observe for growth or changes