EXAM #1: HYPOTHYROID Flashcards Preview

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Flashcards in EXAM #1: HYPOTHYROID Deck (37):
1

What are the major steps of thyroid hormone synthesis?

1) Trapping of iodide (NIS)
2) Organification (add I to thyroglobulin)
3) Coupling (MIT and DIT)
4) Storage (Colloid)
5) Secretion

2

What is the Jod Basedow effect?

Increased T4 formation with Iodide concentration

3

What is the Wolff-Chalikoff effect?

Decreased T4 formation with increased iodide, after initial increase

4

What is the escape effect?

Increased T4 formation AFTER wolff-chalikoff effect

5

What subunit of TSH gives the hormone its specificity?

Beta

6

Aside from TSH, what else can be increased by TRH?

Prolactin

7

What factors increases TGB?

1) Estrogen (pregnancy, BCP)
2) Congenital

8

What factors decreases TGB?

1) Systemic illness
2) Glucocorticoids

9

What is the best test of thyroid function?

TSH

*Note that this will be inversely proportional to thyroid function

10

What are the expected values of TSH and free T4 in hypothyroidism?

- High TSH
- Low FT4

*Note that the TSH will be above the reference range before FT4; thus, more sensitive

11

What are the expected values of TSH and free T4 in hyperthyroidism?

- Low TSH
- High FT4

*Note that the TSH will be below the reference range before FT4; thus, more sensitive

12

What is the utility of radionuclide scans in evaluating the thyroid?

This is used to determine thyroid function

13

What does "subclincal" refer to in regards to interpreting the results of FT4 and TSH levels?

Changes in TSH with normal FT4

14

What labs are associated with primary hypothyroidism?

- High TSH
- Low T3/4

15

What are the possible etiologies of primary hypothyroidism?

1) Thyroiditis
2) Iodine deficiency
3) Radiation
4) Surgery
5) Infiltrative
6) Drugs

16

What are the possible etiologies of secondary hypothyroidism?

1) Surgical
2) Infiltrative/ metastatic
3) Radiation therapy
4) Apoplexy

17

What will the TSH and T4 be in secondary hypothyroidism?

- LOW TSH
- Low T4

18

What is a delayed relaxation phase?

Testing DTR, takes a long time for muscles to relax

*Associated with hypothyroidism

19

What is the most common cause of hypothyroidism in iodine-sufficient areas?

Hashimoto's Thyroiditis

20

What is Hashimoto's Thyroiditis?

Auto-immune destruction of the thyroid

21

What are the major clinical features of Hashimoto's Thyroiditis?

1) Goiter
2) Bossillated feel

22

What antibody is usually elevated in Hashimoto's Thyroiditis?

TPO antibodies

*Note that these are NOT required for diagnosis

23

What is the hallmark US finding in Hashimoto's Thyroiditis?

Heterogenous appearance

24

What causes goiter in iodine-related hypothyroidism?

- Deficiency= gland has to work harder
- Increased TSH= increases size of thyroid gland

25

What is the name of the effect that can cause iodine to lead to hypothyroidism?

Wolff-Chaikoff phenomenon

26

How is hypothyroid treated?

Levothyroxine (T4)

(Roughly 1.5 mcg/kg/day)

27

When is treatment indicated for hypothyroidism?

TSH greater than 10

28

If the TSH is below 10 but the patient is symptomatic, what should you do?

Give a levothyroxine trial

29

When treating hypothyroid, how long should you wait to check a TSH after a dose change?

4-6 weeks

*UNLESSS, patient switches brands of medication, starts birth control, or is pregnant

30

What is Liothyronine?

T3

*Note that this is not usually recommended as therapy

31

What is contained in "natural" thyroid sources, such as Armour Thyroid?

Both T3 and T4

32

How do the thyroid hormone needs change in pregnancy?

Needs for thyroid hormone increase

33

Clinically, what do you need to do with pregnant patients regarding thyroid?

1) Check TSH at diagnosis of pregnancy
2) Monitor TSH 4-6 weeks
3) Doses redcuced post delivery

34

What is myxedema coma?

Acute medical emergency w/
1) Mental status change
2) Hypothermia
3) Hypoglycemia
4) Resp. failure
5) Hypotension
6) Bradycardia

*More common in women, precipitated by infection, CVA, or MI

35

What is the treatment for myxedema coma?

1) Supportive measures/ tx of underlying cause
2) IV thyroxine replacement
3) Hydrocotisone

36

What should you use to guide dose adjustments in secondary hypothyroidism?

Free T4

37

What should T4 NOT be used for?

1) Shrinking nodules
2) Weight loss
3) Treating depression
4) Lowering cholesterol