Thyroid

Question 1

produces TRH which stimulates the pituitary gland to produce TSH. TSH stimulates the thyroid gland to secrete T4, which is converted to T3 in peripheral tissues.

Answer 1

hypothalamus

Question 2

Unbound ___ and ___ is active

___ inhibits TRH and TSH secretion

Answer 2

Unbound T3 and T4 is active

T4 inhibits TRH and TSH secretion

Question 3

TSH <0.3

Answer 3

<0.3 → hyperthyroidism

Question 4

TSH >4

Answer 4

> 4 → hypothyroidism

Question 5

TSH 0.3-4

Answer 5

0.3-4 → euthyroidism

Question 6

_____correlates most to thyroid state

_____ only ordered when evaluating hyperthyroidism

Answer 6

Free T4

T3

Question 7

found in Hashimoto’s and Graves disease

Answer 7

Anti-TPO (thyroid peroxidase) antibodies

Question 8

can distinguish between hot and cold nodules

Answer 8

Iodine isotope scans: preferred

Question 9

Hot nodules: ______

Cold nodules: _______

Answer 9

Hot nodules: usually benign

Cold nodules: usually benign, however malignant neoplasms are cold nodules

Question 10

how to assess goiters

Answer 10

CT and MRI

Question 11

how to differentiate solid from cystic thyroid nodules.

Answer 11

US… Can guide fine-needle aspiration.

Question 12

less physical findings; low TBG level is diagnostic. T4 normal.

Answer 12

TBG deficiency

Question 13

causes mental retardation if not tx; irreversible brain damage, growth failure, deafness, and neurologic abnormalities
Newborn screening and early aggressive tx is necessary to prevent complications. TBG deficiency

Answer 13

Congenital Pediatric Hypothyroidism

Question 14

less physical findings; low TBG level is diagnostic. T4 normal.

Answer 14

TBG deficiency…Congenital Pediatric Hypothyroidism

Question 15

autoimmune condition leading to destruction of the thyroid gland.

Answer 15

Hashimoto thyroiditis:

Question 16

main cause worldwide (not in US d/t iodine-fortified foods)

Answer 16

Iodine Deficiency

Question 17

growth failure, goiter, delayed puberty, delayed dentition, weight gain, fatigue, hyperlipidemia
PE:
Birth: often newborn appears normal; jaundice, constipation, or umbilical hernia. Poor feeders, cool cyanotic extremities
Older children: delayed growth and puberty, goiter, weight gain

Answer 17

Pediatric Hypothyroidism

Question 18

TSH ↑

T4 free = WNL or ↓

Answer 18

Primary Hypothyroidism

Question 19

TSH = WNL

T4 free = ↓

Answer 19

Central Hypothyroidism

Question 20

TSH = WNL
T4 free = WNL
Total T4=

Answer 20

TBG Deficiency

order TBG level

Question 21

How to tx Pediatric Hypothyroidism

Answer 21

levothyroxine→ no liquid suspension in US; parents may need to crush and mix. Long half-life- if dose is missed skip and take next day.
Redraw labs 2-4 weeks after initiating therapy. Once TSH is normalized, frequent monitoring 2-4mos to ensure optimal development
TSH elevated in primary hypothyroidism = increase dose
Low T4 free in central = increase dose

Question 22

thyroid stimulating Ig binds to TSH receptor, causing excessive stimulation
Neonatal is often passed on from mother and resolves in 3mos,however tx is necessary to prevent morbidity and mortality

Answer 22

Pediatric Hyperthyroidism:

Graves Disease

Question 23

CM: palpitations, tremor, emotional lability. Increased appetite and weight loss. fatigue , muscle weakness, hyperdefecation. Poor sleep and concentration
PE: goiter (almost 100%), audible thyroid bruit, tachycardia, wide pulse pressure, underweight, hyperreflexia, warm moist skin; exophthalmos or eyelid lag. Nodule.

Answer 23

Pediatric Hyperthyroidism:

Graves Disease

Question 24

TSH= ↓
T4 free= ↑
Total T4= ↑
T3= ↑↑

Answer 24

Pediatric Hyperthyroidism:

Graves Disease

Question 25

how to tx Pediatric Hyperthyroidism: | Graves Disease

Answer 25

refer to pediatric endocrinologist Methimazole → Graves disease Propylthiouracil (PTU) → reserved for those allergic to methimazole → high risk of AE (agranulocytosis, vasculitis, hepatitis, and liver failure)

Question 26

Causes hypothyroidism: blocks the uptake of iodine and the release of thyroid hormone and induce chronic autoimmune thyroiditis.

Answer 26

Lithium

Question 27

can cause hyper or hypothyroidism. effects can be seen for 2-3 years after d/c Usually causes hypothyroidism in the US. No need to stop, replace levels with levothyroxine Larger than normal dose of levothyroxine may be needed to reach tx goals Goals: TSH normal-high; free t4 mid-low normal Hyperthyroidism occurs in iodine-deficient areas of the world; CM often masked d/t beta blocking activity of _____

Answer 27

Amiodarone

Question 28

CM: redevelopment of atrial arrhythmias, exacerbation of ischemic heart disease or CHF, restlessness, and low-grade fever. Tx: oral steroids and antithyroid drug tx. Maybe thyroidectomy.

Answer 28

Amiodarone caused hyperthyroid

Question 29

*Perform _____ before initiating amiodarone therapy if possible*

Answer 29

TFT

Question 30

treatment of hep B and C or malignant disease. Use can induce production of thyroid antibodies resulting in hypothyroidism or thyrotoxicosis. Discontinuation will cause the antibodies to disappear.

Answer 30

Interferon alfa

Question 31

(sunitinib, sorafenib, imatinib) treat renal cell carcinoma and GI stromal tumors. Increased metabolism of thyroid hormone. Hyperthyroidism may also occur.

Answer 31

Tyrosine kinase inhibitors

Question 32

can interfere with diagnostic assays (falsely low TSH and falsely elevated T3 and T4). Hold dose for 3 days prior to checking TFTs.

Answer 32

Biotin

Question 33

may be caused by iodine deficiency (many iodine fortified foods in US), previous radiation.

Answer 33

Hypothyroidism

Question 34

hypothyroidism with goiter | ↑TSH and presence of antithyroid Ab

Answer 34

Hashimoto (autoimmune) thyroiditis

Question 35

fatigue, cold sensitivity, weight gain, hoarseness, puffiness of face and hands, heavy and irregular menses, dry skin, dry brittle hair, depression, paresthesias, muscle aches, constipation. PE: lethargic, expressionless, depression, agitation. Texture and color of skin and hair. Deepened voice, slowed HR. Delay in achilles tendon DTR. elevated DBP.

Answer 35

Hypothyroidism

Question 36

Thyroid gland: large or small. | Tenderness suggests ____

Answer 36

subacute thyroiditis.

Question 37

Thyroid gland: large or small. | Nontender suggests _____

Answer 37

chronic

Question 38

Thyroid gland: large or small. | Rubbery-firm and symmetric = ____

Answer 38

Hashimotos

Question 39

↑ TSH. ↓ T4 free. ↓ T4 free index Anti-TPO Ab elevated in chronic autoimmune US only to view nodules; FNA if suspicious nodule EKG: low voltage; cardiac enlargement. Bradycardia

Answer 39

Hypothyroidism

Question 40

tx of hypothyroidism

Answer 40

levothyroxine to return TSH to normal level; euthyroid levels can be achieved in 4-6wks, then monitor twice yearly If pt start estrogen therapy recheck TSH in 12 wks (may increase T4 requirements)

Question 41

type of thyroid disease that causes goiter?

Answer 41

Hypo and Hyperthyroidism

Question 42

(most common cause): autoimmune. F>M age 20-40yo. Autoantibodies bind to TSH receptor sites and stimulate thyroid hormone secretion

Answer 42

Graves disease- Hyperthyroidism

Question 43

1st lab to assess with thyroid what to order if it is abnormal?

Answer 43

``` TSH Normal range (euthyroid) 0.3-0.4 If TSH is abnormal request T4 if elevated= hyperthyroid if suppressed= hypothyroid ```

Question 44

CM: eye changes (NOSPECS) No signs or symptoms, only signs (no symptoms), soft tissue swelling, proptosis, extraocular muscle paresis, corneal involvement, sight loss)

Answer 44

Graves disease- Hyperthyroidism

Question 45

can help distinguish Graves vs. thyroiditis

Answer 45

Radioiodine uptake

Question 46

identify toxic multinodular goiter or solitary nodular goiter

Answer 46

Iodine scan

Question 47

common to see elevated liver enzymes.

Answer 47

Graves

Question 48

IN this condition TSH (initial) → will remain suppressed for 3 mos after initiating tx, therefore must follow T4 Free or free T4 index

Answer 48

Hyperthyroidism

Question 49

Tx of Graves:

Answer 49

Beta blockers (tremor, tachycardia) → propranolol or atenolol (caution CHF and bronchospasm; CI pregnancy) Methimazole (MMI) and propylthiouracil (PTU): thioamides PTU→ not first line d/t severe AE (liver failure) Pregnancy→ PTU in first trimester, then MMI Small goiters and mild hyperthyroidism: MMI 5-10mg daily

Question 50

definitive; recommended if relapse after MMI or PTU tx or for pts OLDER than 20

Answer 50

Radioiodine ablation

Question 51

Complications of untreated Graves

Answer 51

A fib, CHF, angina, osteoporosis

Question 52

progressive and severe hypothyroidism with skin thickening and CV and renal manifestations... Slowed mentation, respiratory depression, may progress to death Triggered by stress, cold, trauma, infection, or medications

Answer 52

Myxedema

Question 53

How to tx Myxedema

Answer 53

Tx: IV levothyroxine and glucocorticoid therapy; warming, ventilatory support

Question 54

asymptomatic TSH elevation with normal free T4

Answer 54

Subclinical hypothyroidism

Question 55

Tx if: TSH>10; consider if TSH 4.5-10 especially in patients with infertility, irregular menses, depression, and fatigue Risk of tx is development of subclinical hyperthyroidism; untreated pts are at risk for cardiac dysfunction, elevated LDL and cholesterol, neuropsychiatric dysfunction, progression to overt hypothyroidism Stabilize TSH then check yearly

Answer 55

Subclinical hypothyroidism

Question 56

suppressed TSH with normal T4 and T3. Initiate tx if TSH< 0.1 as result of Graves or nodular disease, esp if older than 60, increase risk heart disease, osteopenia, or osteoporosis.

Answer 56

Subclinical hyperthyroidism

Question 57

Thyroid enlargement is ______ in pregnancy Dietary iron requirements are higher in pregnancy: supplement with 150mcg potassium iodine. Free T4 levels may be inaccurate during pregnancy

Answer 57

normal

Question 58

is CI during pregnancy, therefore we cannot determine the cause of hyperthyroidism Graves disease is most common cause: goiter, exophthalmos, and pretibial myxedema TSH ↓, free T4 ↑, T3 ↑ Consider TRAb Consider US

Answer 58

Radioiodine

Question 59

how to tx hyperthyroid in pregnancy

Answer 59

PTU during 1st 1st trimester (MMI is teratogenic) 2nd trimester: d/c PTU (d/c risk of hepatotoxicity) and start MMI Monitor free T4 and TSH monthly→ goal: t4 high: normal and TSH low-normal Beta blockers if severe→ atenolol or propranolol preferred. Wean once controlled by thioamide Monitor fetal HR and growth

Question 60

HYPOTHYROIDISM IN PREGNANCY

Answer 60

Goal TSH: 0.5-2.5 Once pregnancy confirmed, increase dose of levothyroxine by 30% Monitor TSH and T4 free every month for first half of pregnancy, then each trimester.. Adjust dose in 12 - 25mcg increments Once postpartum, return to prepregnancy dose. Recheck levels 6 wks pp

Question 61

How to dx. Thyroid nodules

Answer 61

TSH (initial). If TSH suppressed and nodule >1cm order free T4, T3 and radionucleotide scan. FNA biopsy on warm and cold nodules. If TSH elevated: check T4 free. Start levothyroxine as indicated TSH normal: US then FNA if needed

Question 62

Thyroid masses and thyroid CA

Answer 62

T- tumor size N- lymph nodes M- metastases

Question 63

how to tx Thyroid masses and thyroid CA

Answer 63

Tx: ablation with radioactive iodine when mets, large tumors, or high risk. Thyroid replacement or suppression therapy will be necessary.

Question 64

pt education after r radioiodine treatment or scanning

Answer 64

No sharing saliva for 5 days. No close contact with infants, kids <8, or pregnant women for 5 days. No breastfeeding. Flush toilets twice. Acetaminophen or ASA for sore throat.

Question 65

rare, life threatening –HYPERthyroid Temp 102-105, profuse sweating, pulse 120-140bpm, a fib, restlessness, confusion, agitation, coma. GI: Severe v/d, and hepatomegaly with jaundice

Answer 65

Thyroid Storm