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Flashcards in Thyroid Deck (46):
1

What does the hypothalamus secrete on the thyroid?

Thyrotropin releasing hormone

2

How does TRH reach the pituitary gland?

Via portal circulation

3

What does the pituitary gland produce when it is stimulated by TRH?

The pituitary gland produces and secretes thyroid stimulating hormone (TSH)

4

What is the mediate stimulus to the thyroid cells?

TSH

5

What do the thyroid cells secrete when they are stimulated by TSH?

T3 and T4

6

What does T3 stand for?

triiodothyronine

7

What does T4 stand for?

thyroxine

8

What makes T3 and T4 unique compared to the rest of the body?

They contain iodine

9

What absorbs iodine? How does this effect the thyroid?

-Iodine is absorbed in the intestine
-Iodine is taken in by the thyroids follicle cells

10

Describe the iodine concentration of the thyroid gland compared to the plasma

The thyroid gland typically achieves iodine concentrations 50 times greater than that of the plasma.

11

How does iron form T4 and T3

Iodine is then used in combination with other amino acids to form T4 and T3.

12

How is T3 and T4 transported in the blood?

In the blood, most T3 and T4 are transported bound to alpha globulins and albumin.

13

What is the principle protein involvedin transporting T3 and T4?

The principle protein involved is known as thyroxine-binding globulin (TBG).

14

Do bound T3 and T4 stimulate target tissues?

NO! only unbound ones stimulate target tissues

15

Are quantities on unbound T3 and T4 large or small?

Small

16

What are examples of thyroid target tissues in the body?

Virtually all cells

17

What is the effect of thyroid hormone?

-Metabolic
-Promotes utilization of carbohydrates, proteins, and lipids

18

What are the primary effects of thyroid hormones?

-Aerobic energy metabolism
-Glucose metabolism
-Protein metabolism
-Lipid metabolism
-Ion transport

19

What are examples of secondary effects of thyroid hormones?

-Growth/development
-Cardiac output
-Ventilation
-CNS activity
-Thermoregulation
-Muscle function
-GI activity
-Reproductive functions

20

What are examples of basic problems that you can have with your thyroid?

-Excessive T3 and T4
-Deficient T3 and T4
-Malfunction of the gland itself
-Defect in the anterior pituitary/hypothalamus control system

21

Describe thyroid hormone hypofunction

Thyroid hormone secretion is inadequate to maintain normal levels of target tissue stimulation

22

What causes most adult hyposecretion of thyroid?

-Surgical resection or radiation therapy after a hyperactive state

23

What is disorder seen in newborns where normal growth and tissue differentiation are impaired.

Cretinism

24

Other thyroid hypoperfusion causes

-Penetrating wounds to the neck that produce inflammation.
-Bacterial or viral infections especially to the mouth or throat region
-Iodine deficiency
-Insufficient stimulus by hypothalamus/pituitary
-Therapeutic drugs that have thyroid blocking side effects
-Pregnancy and puberty

25

What is the most common hypothyroid disease?

Hashimotos’s thyroiditis

26

Describe hashimotos thyroiditis

-Autoimmune disease where antibodies to follicle cells in the thyroid are present
-Autoimmune disease where antibodies to follicle cells in the thyroid are present

27

Symptoms of hypothyroidism

-Weakness
-Fatigue
-Cold intolerance
-Weight gain
-Constipation
-Bradycardia
-Memory loss

28

What are causes of hyperactive thyroid?

-Excess thyroid hormones
-Thyroid injury (rare)
-Thyroid tumors
-Toxic Nodular Goiter

29

What is the most common cause of thyroid hyperfunction?

Graves Disease

30

Characteristics of Graves Disease

-Thyroid gland grows to 2-3 times normal size
-Autoimmune disease
-Usually effects young females
-Antibodies are not against thyroid cells but against TSH receptors.
-They bind to TSH receptors and therefore stimulate thyroid secretion.

31

Symptoms of hyperthyroidism

-Muscle wasting
-Increased activity
-Heat intolerance
-Weight loss
-Insomnia
-Diarrhea, nausea and vomiting
-Tachycardia
-Tremor

32

What is the most sensitive measurement of thyroid function?

TSH

33

What are all the things that can be measured in a thyroid function test

-THS
-T3
-T4
-Free T3
-Free T4
-Antithyroid antibodies

34

This measures the amount of unbound T4 that is actually acting on the target tissues.

Free T4

35

Are T3 levels used often?

No- they are seldomly used

36

What can be measured to determine autoimmune disease?

Antithyroid antibodies

37

Describe TSH levels in hypothyroidism

TSH is usually 10-100 times normal by the time symptoms develop

38

Describe T4 and Free T4 in hypothyroidism

Low

39

Describe anti-TPO antibodies in hypothyroidism

Anti-TPO (anti-thyroid peroxidase antibodies) levels will be elevated in Hashimoto’s thyroiditis

40

Describe TSH levels in hyperthyroidism

Below normal

41

Describe T4 and Free T4 in hyperthyroidism

Increased

42

Describe anti-TPO antibodies in hyperthyroidism

Anti-TSH receptor antibodies will be elevated in Grave’s disease

43

When your patient is hypothyroid, what do they need to make up for that?

Suppliments

44

What is the best test of choice to follow therapy

TSH

45

How long does it take thyroid medication to stabilize TSH levels

6 weeks

46

How often should the patients TSH be monitored to make sure they are on the proper dose?

6-12 months