Endocrinology_Hyperthyroidism and thyrotoxicosis

Question 1

What is thyrotoxicosis?

Answer 1

A condition resulting from exposure of body tissues to excessive levels of thyroid hormones.

Question 2

what causes thyrotoxicosis?

Answer 2

• hyperthyroidism
• thyroiditis
• exogenous thyroid intake.

Question 3

dermatologic manifestation of thyrotoxicosis

Answer 3

• sweating
• hair thinning
• onycholysis or separation of nail from nail bed
• warm skin.

Question 4

Cardiovascular manifestation of thyrotoxicosis

Answer 4

• Tachycardia
• wide pulse pressure
• elevated systolic blood pressure
• atrial fibrillation in 10 to 20% of patients with hyperthyroidism.

Question 5

Respiratory manifestation of thyrotoxicosis

Answer 5

• increased oxygen consumption
• respiratory muscle weakness leading to dyspnea.

Question 6

gastrointestinal manifestation thyrotoxicosis

Answer 6

• increased basal metabolic rate
• increased gut motility leading to weight loss and diarrhea.

Question 7

hematologic manifestations of thyrotoxicosis

Answer 7

• plasma volume increases more than red blood cell mass leading to normocytic anemia.

Question 8

Genitourinary manifestation of thyrotoxicosis

Answer 8

• urinary frequency
• anovulatory infertility
• oligomenorrhea
• amenorrhea

Question 9

musculoskeletal manifestation of thyrotoxicosis

Answer 9

• proximal muscle weakness
• tremor best seen in the outstretched hands, or in the tongue
• increased bone resorption leading to osteoporosis.

Question 10

psychiatric manifestation of thyrotoxicosis

Answer 10

anxiety.

Question 11

What is the single best lab test to assess thyroid function?

Answer 11

thyroid stimulating hormone (TSH)

Question 12

high free T4 and low TSH

Answer 12

thyrotoxicosis

Question 13

Normal free T4 and low TSH

Answer 13

subclinical hyperthythyroidism

Question 14

what test should you order, if both free T4 and TSH are elevated?

Answer 14

• MRI to look for a TSH producing pituitary adenoma
• can also present with a visual defect.

Question 15

differentiate the causes of thyrotoxicosis based on Thyroid size

diffusely enlarged goitre

Answer 15

• Graves disease
• toxic multinodular goite - in countries with low iodine intake

Question 16

differentiate the causes of thyrotoxicosis based on Thyroid size

palpable nodule

Answer 16

thyroid adenoma

Question 17

differentiate the causes of thyrotoxicosis based on Thyroid size

Normal thyroid size

Answer 17

• subacute thyroiditis
• exogeneous hyperthyroidism (factitious vs. iatrogenic)
• ectopic hyperthryroidism (struma ovarii)

Question 18

What is struma ovarii?

Answer 18

• Functioning thyroid tissue in an ovarian neoplasm

Question 19

what physical findings are unique to Graves disease?

Answer 19

• ophthalmopathy
• infiltrative dermopathy

Question 20

Describe the ophthalmology seen with graves disease?

Answer 20

• stare
• lid lag
• exophthalmos

Question 21

What is lid lag?

Answer 21

When a person with Graves disease looks down, the upper sclerae can be seen since the upper eyelid closes slowly

Question 22

What causes the exophthalmos in Graves disease?

Answer 22

• The eyes pushed outward secondary to inflammation of the extraocular muscles and orbital fat

Question 23

Describe the infiltrator dermopathy seen and Graves disease

Answer 23

• pretibial myxedema with raised hyperpigmented, violaceous, orangepeel textured papules

Question 24

Describe the pathology behind Graves disease

Answer 24

• An autoimmune disorder characterized by TSH receptor antibodies

Question 25

Besides the physical examination how can you diagnose cause of thyrotoxicosis

Answer 25

* radioactive iodine uptake (RAIU) scan

Question 26

What does high radio iodine uptake on a radioactive iodine uptake (RAIU) scan indicate

Answer 26

* de novo hormone synthesis.

Question 27

is a treatment with radioiodine ablation, or thionamides. (methimazole and prophylthiouracil) appropriate when radioiodine uptake scan show a high uptake?

Answer 27

either will decrease hormone synthesis.

Question 28

What does low radio iodine uptake (on a radioactive iodine uptake scan) indicate?

Answer 28

destruction of thyroid tissue with release of preformed hormone or extrathyroidal source.

Question 29

If a patient has low radioiodine uptake - is treatment with radioiodine ablation or thionamides appropriate?

Answer 29

NO

Question 30

What are causes of high radioiodine uptake ?

Answer 30

* Graves disease causes a diffuse uptake. * Toxic adenoma * toxic multinodular goitre * TSH producing pituitary adenoma * beta human chorionic gonadotropin (bHCG) mediated hyperthyroidism.

Question 31

What are causes of beta hCG mediated hyperthyroidism?

Answer 31

* hydatidiform mole * choriocarcinoma * Testicular germ cell cancer

Question 32

Why does high beta hCG cause hyperthyroidism?

Answer 32

* beta hCG has some TSH-like activity due to their shared alpha subunit

Question 33

What are causes of low radioiodine uptake?

Answer 33

* thyroiditis * exogenous thyroid ingestion, or * ectopic thyroid.

Question 34

What is thyroiditis?

Answer 34

* transient increase in thyroid hormones, secondary to the release of preformed.

Question 35

What are some causes of thyroiditis?

Answer 35

* viral/subacute * postpartum * Chemical(amidarone induced) * post radiation.

Question 36

How do you differentiate between the causes of subacute thyroiditis?

Answer 36

* subacute granulomatous thyroiditis is painful * subacute lymphocytic thyroiditis is painless, and often occurs postpartum approximately six weeks postpartum.

Question 37

How do you treat thebeta-adrenergic symptoms (tachycardia, tremor) of thyrotoxicosis?

Answer 37

* propranolol

Question 38

What are the main treatments of hyperthyroidism ?

Answer 38

* Thionamides * radioactive iodine ablation (ablation within six to 18 months) * thyroidectomy

Question 39

What supplementation will a patient need after undergoing ablation or thyroidectomy?

Answer 39

* Livothyroxine

Question 40

Which thionamed should be used during pregnancy?

Answer 40

* propylthiouracil PTU, because he does not readily cross the placenta.

Question 41

What characteristics would make you more concerned that a thyroid nodule was malignant?

Answer 41

* History of neck irradiation * "cold" nodule * male sex * firm and fixed solitary nodule.

Question 42

What is a cold nodule?

Answer 42

* The absence of uptake in one nodular region on radioiodine uptake scan

Question 43

What should you order to evaluate a cold nodule?

Answer 43

* fine needle aspiration (FNA) of the nodule.

Question 44

How do you treat subacute thyroiditis?

Answer 44

* beta blockers for thyrotoxicosis or * levothyroxine for hypothyroidism * anti inflammatory medications.