E: Hpa And Thyroid 3

Front 1

What are the negative feedback molecules for the Thyroid axis?

Back 1

T3 and T4 feed back on the hypothalamus AND the pituitary to inhibit TRH and TSH respectively.

Front 2

What has a longer serum half-life, T3 or T4?

What are the Thyroid function tests that are of actual use?

Back 2

T4

Thyroid (T4) Panel or Free T4
TSH

Front 3

What tests can assess the intrinsic actv of the thyroid?

Back 3

(1) Radioactie iodine uptake (RAIU): increased in hyperthyroid and iodine def.; decreased in hypothyroidism and thyroiditis
(2) Thyroid scan: uses localized rates of active transport of iodine.

Front 4

State whether the following give an increased RAIU or decreased RAIU:
- Factitious
- subacute or silent thyroiditis
- Graves dz
- thyroid adenoma
- iodine-induced
- toxic multinodular goiter

Back 4

- Increased RAIU
Graves Disease
Toxic Multinodular Goiter
Thyroid Adenoma
- Decreased RAIU
Subacute or Silent Thyroiditis
Iodine-Induced
Factitious

Front 5

What is the utility of a thyroid ultrasound?

Back 5

May be useful to accurately determine size for purposes of documenting therapeutic efficacy

Front 6

What is a myxedema coma?

Is goiter w/i the range of possible presenting sx of hypothyroidism?

Is hypothyroidism onset usually acute?

Back 6

profound, severe hypothyroidism.

yes.

no, gradual.

Front 7

[There is a] “marked increase in the general bulk of the body, inelastic swelling of the skin [non-pitting], dryness and roughness…. Perspiration is often much decreased. …the features are coarse and broad, the lips thick, the nostrils broad and thick, and the mouth is enlarged. There is a striking slowness of thought and movement. The memory becomes defective, the patients grow irritable and suspicious, and there may be headache. In some instances their gait is heavy and slow.”

---top of the DDx?

Back 7

hypothyroid.

Front 8

What are some of the constitutional sx of hypothyroidism? Skin related? CV? GI? OB? MSK? Hematological? neurologic?

Back 8

- cold intolerance, fatigue, lethargy, hoarseness
- thickened/yellowed, dry, non-pitting edema, cool, \persperation, alopecia
- \contractility, \HR, \CO, ^PVR. CHF is rare.
- \appetitie, constipation, WG
- menorrhagia, menstrual irreg.
- myalgias, arthralgias
- anemia
- delayed relaxation of DTRs, Difficultly concentrating, poor memory, somnolence, Depression, HA, paresthesia.

Front 9

Give the possible etiologies for the following combos:
- low TBG, wnl TSH
- wnl TBG and TSH
- wnl TBG, raised TSH antibody

Back 9

- severe hypoproteinemia, drugs, heredity
- severe non-thyroid illness, drugs (aspirn, phenytoin).
- AI thyroiditis, subclinical hypothyroid or compensated euthyroid.

Front 10

How do drugs like Li, iodine, and amiodarone cause hypothyroidism?

Back 10

drug-induced defects w/ T4 biosynthesis.

Front 11

What is the #1 cause of hypothyroidism?
- main features?
- physical findings?
- permenance?

Back 11

AI thyroiditis (Hashimoto's, chronic lymphocytic)
- high titers of antiThyroid antibodies & lymphocytic infiltration of thyroid gland w/ fibrosis.
- firm, non-tender diffuse goiter
- usually permenant

Front 12

What are antibodies against in Graves?
- can they cross the placental barrier?
- can T4/T3 cross the barrier?
- TSH?

Back 12

against TSH receptor --> cause activation
- yes they can, may cause transient neonatal Graves.
- limited
- no

Front 13

FTT, prolonged neonatal jaundice, umbilical hernia, increased Wt for Ht per age, protuding tongue, and delayed bone age can be signs of what in infants?
- does school performance suffer?

Back 13

Hypothyroidism.
- not usually

Front 14

Tx of Hypothyroidism?
- what is the tx goal?

Back 14

replace w/ levo-thyroxine (L-T4)
- to normalize TSH lvls.

Front 15

Chronic non-compliance or undx'ed hypothyroidism can cause what?
- precipitating factors
- sx?
- tx?

Back 15

Myxedema Coma (Severe Hypothyroidism)
- severe illness, surgery, sedative drugs, anesthetics
- Bradycardia, Hypotension
Hypothermia
Hypoventilation
Stupor, Coma
Delayed deep tendon reflexes
Dry, puffy skin
History of thyroid surgery, T4 supplementation, or RAI
- tx underlying disorder, thyroid hormone dose is controversal (T4); avoid T3 b/c of possible MI
+ IV hydrocortisone is also indicated

Front 16

What is the most common cause of Hyperthyroidism? What else can cause it? Non-goitrous causes?

What are the useful labs for hyperthyroidism?

Back 16

Toxic Diffuse Goiter (Grave's) (70%)
- multinodular goiter, toxic adenoma
- thyroiditis, thyroid hormone use, uncommon/rare dz

-TSH, Free T4 or T4 panel... rarely T3.

Front 17

Sinus Tachy, Afib, CHF (High Output), angina, increased pulse pressure, tremor, proximal muscle weakness, anxiety, hyperactivity, heat intolerance, excessive perspiration, WL, diarrhea, warm skin, mania, disorientation, coma, seizures and convulsions are all sx of which thyroid dz?

Back 17

Hyperthyroidism.

Front 18

Is there a specific lab test for Grave's dz?
- RAIU results?
- can TSI tests help?

Back 18

No.
- elevated
- yes, but they're not usually indicated.

Front 19

Graves dz can run the gamut from subclinical, to single self-resolving episode, to severe permanent dz.

T/F?

Favorable prog indications?

Back 19

T

female, small goiter, caught early

Front 20

What is toxic multinodular goiter?
- clincal features and dx?
- TSH lvls initially?

Back 20

Final phase of evolution of goiter over time
Nodules gradually acquire autonomy
- RAIU up, mult nodules on US. Scintigraphy shows diffuse patchy uptake.
- \TSH wnl T4/T3 (remember the progressive diagram)

Front 21

monoclonal expansion of thyroid follicular cells that is almost never malignant is called...
- regulated by TSH?
- size of majority of these lesions?
- RAIU?
- scintigraphy?

Back 21

toxic adenoma (nodule).
- no, escapes regulation.
- >2.5cm
- elevated
- solitary, HOT nodule.

Front 22

How is Hyperthyroidism tx'ed?

Back 22

antithyroid drugs
- methimazole
- propylthiouracil
Radioactive Iodine
Surgery
Ancillary Drugs (iodine)

Front 23

What do methimazole and propythiouracil do?
- speed of drug effect onset?
- affect size of the goiter?
- SE?

Back 23

Block production of T4/T3 at several levels
- take several weeks to reach full therapeutic effectiveness
- do not affect size of the goiter, only the level of thyroid hormone production.
- **rare agranulocytosis, rash, muscle joint aches, HA, N/upset stomach, altered taste sensation, fever, Hair loss, hepatitis, nephritis.

Front 24

Is it possible to predict the agranulocytosis that anti-thyroid drugs can cause? Is routine CBC surveillance helpful?
- window of most likely devleopment?
- dose-dependent?
- warning signs?

Back 24

no.
no.
- right after tx start, but can be anytime thereafter too.
- v. unlikely to develop on low doses of methimazole, threshold for PTU unclear.
- stop meds if they get a fever & ST, and check CBC w/ differential.

Front 25

Is there increased risk of thyroid CA w/ using radioactive iodine?
- effectiveness?
- major drawback?
- what grave's sx might be exacerbated?

Back 25

no.
- 70-90% of cases are tx'able
- hypothyroidism
- opthalmopathy.

Front 26

What utility do B-blockers have in hyperthyroid tx?

Back 26

can help w/ the palpitations

Front 27

When is normal iodine used in hyperthyroidism?
- mech?
- effect on vascularity?

Back 27

SEVERE cases.
- inhibits thyroid hormone synth/release
- decreases vascularity of the gland

Front 28

What is the Thyroid storm? ZOMG O_o
- sx
- precipitating factors?
- mortality?
- tx?

Back 28

Clinical dx at the end of hyperthyroid continuum.
- fever, Mental status changes, CV collapse
- surg, sepsis, iodine loads, post-partum
- 20-50%
- PTU, followed by iodine, propranolol if no ht failure, Dexamethasone; as always, also tx underlying causes.