ANCCBoardReviewThyroidCo-small00center10-2114007

ANCC Board Review: Thyroid ConditionsStudy this set online at: http://www.cram.com/flashcards/2114007

Normal Lab Values: TSH 0.4 - 4.0 mU/LPopulation mean TSH

value.1.2 mU/L.

This should be the target when titrating levothyroxine.

Normal Lab Values: FreeT4 10 - 27 pmol/L

Clinical significance oftotal T4 levels.

Total T4 includes the free and protein bound T4 but itis NOT useful clinically. It is altered by the presence of

exogenous estrogen, methodone, pregnancy, liverdisease, etc.

Clinical significance ofTSH levels.

Most reliable test of thyroid function. Used todiagnose all forms of hyper- and hypo

thyroidism and to titrate thyroid replacement.

Clinical significance offree T4 levels.

After TSH, this is themost useful diagnostically.

Source of circulating T3.20% is produced in the thyroid.

80% is converted peripherally fromT4.

Clinical significance ofAntiperoxidase Antibody.

Peroxidase is an enzyme found inthyroid cells. Presence of this enzymeindicates autoimmune thyroid disease.


Synonyms ofAntiperoxidase Antibody.

Antimicrosomal antibody, thyroidperoxidase antibody (TPOAb),

antithyroid antibody.

Hypothyroidism should beconsidered when a patient presents

with this gynecological complaint:New onset menorrhagia.

S/Sx of hypothyroidism:integumentary system.

Thick, dry skin.Thick, coarse hair that breaks easily.

Thick, dry nails.

S/Sx of hypothyroidism:cardiac.

Bradycardia but only insevere cases.

S/Sx of hypothyroidism:GI. Constipation.

S/Sx of hypothyroidism:reflexes.

Hyporeflexia."Hung up reflexes" where relaxation phase

is slowed more than contraction phase.

S/Sx of hypothyroidism:GYN. Menorrhagia.

S/Sx of hypothyroidism:weigh.

Slight weight gain of ~5lb, mostly fluid.


S/Sx of hypothyroidism:mentation.

Lethargy, "thoughts too slow,"can't make sense of things.

S/Sx of hypothyroidism:environmental sensitivity. Cold intolerance.

S/Sx of hypothyroidism:musculoskeletal. No change.

S/Sx of hyperthyroidism:integumentary system.

Smooth, silky skin that is sometimes moist.Fine hair/loss of hair.

Thin, brittle nails.

S/Sx of hyperthyroidism:weight.

Loss of ~10 lb. Weight lossis present in ~50% of cases.

S/Sx of hyperthyroidism:cardiac. Tachycardia, palpitations.

S/Sx of hyperthyroidism:reflexes. Hyperreflexia.

S/Sx of hyperthyroidism:mentation.

Racing mind, "can't makesense."


S/Sx of hyperthyroidism:GI.

Frequent, low-volume,loose stool.

S/Sx of hyperthyroidism:GYN. Oligomenorrhea.

S/Sx of hyperthyroidism:environmental response. Heat intolerance.

S/Sx of hyperthyroidism:muscle strength.

Proximal muscleweakness.

Name 3 medications thatmay cause hypothyroidism.

Lithium, amiodarone,interferon.

Name two medications thatmay cause hyperthyroidism. Amiodarone, interferon.

Presence of both hyper- andhypothyroidism suggests the patient

is at increased risk for:

Other autoimmune conditions suchas DM1, pernicious anemia, vitiligo,

lupus, RA, Sjogren syndrome.

Population prevalence ofthyroid disorders. 7%


Increased risk for thyroid conditionsis present in these parts of the

lifespan. Elderly, postpartum.

Are thyroid conditions moreprevalent in men or women? Women.This genetic condition is associated

with increased risk for thyroidconditions. Down syndrome.

This is the most helpful lab testto confirm an abnormal TSH. Free T4.Most common cause of

hypothyroidism. Hashimoto thyroiditis.

Expected immune titer findingsin Hashimoto thyroiditis.

High levels of anti-TPO(peroxidase) and anti-thyroglobulin.

What is the most commoncause of goiter in the US? Hashimoto thyroiditis

Physical exam findingswith Hashimoto thyroiditis.

Firm, diffusely enlargedthyroid with fine nodules.


Do patients with Hashimotothyroiditis usually complain of pain?

No, but some neck fullness ortightness is sometimes noted.

Is T3 or T4 more metabolicallyactive on body tissues? T3.Instructions for taking

levothyroxine, and rationale.Take first think in the morning with water ONLY. Wait at least 30

minutes before eating.

Levothyroxine is chelated by almost all metals (such as inantacids, iron, milk, etc.), which significantly alters absorption.

T/F: Levothyroxine requirementsare usually stable once titrated. True.

Define subclinicalhypothyroidism.

Elevated TSH, normal T4,and no symptoms.

Indications for initiating levothyroxinein subclinical hypothyroidism.

When TSH > 10 mU/L, as this is often accompanied by significantincrease in LDL.

Also consider starting when TSH >5 mU/L if antithyroid antibodiesare present or the patient has a goiter.

Management principles forsubclinical hypothyroidism:

If levothyroxine will not be initiated,watch and wait with TSH monitoring

q 6 months.

Usual starting dose oflevothyroxine:

For healthy adults: 1.6 mcg/kg/day, or about 75-125mcg/day.

For elders: 1.0 mcg/kg/day or about 75% or adult dose.


Which of these is a bio-identical hormone:a) levothyroxine

b) Armour Thyroidc) Nature-Throid

d) Westhroid

a) Levothyroxine.

The others are dessicated thyroid preparationscontaining T3 and T4 from porcine thyroid.

How does pregnancy increasethyroid medication needs?

Levothyroxine needs increase by ~50%during pregnancy. Adjust dose upward by~33% as soon as pregnancy is confirmed.

Considerations for initiatinglevothyroxine in the elderly:

Due to cardiovascular risk, the dose should be titratedslowly over 1-2 months. For example, start with 25% of

predicted dose, then add 25% every 2 weeks. Then wait 6-8 weeks after reaching total dose before checking TSH.

At what interval should TSH bereassessed when titrating thyroid

replacement therapy? Every 6-8 weeks.

Levothyroxine is typicallytitrated by this amount: 12.5 - 25 mcg

Anticipatory guidance when startingyoung, healthy people on the entire

anticipated levothyroxine dose.They may feel jittery,

shaky or nervous.

A patient who is taking levo 75 mcg dailyhas TSH = 4.5 mU/L on 8-week follow-up

measurement. Next best action is to:

Increase by 25 mcg/day and reassess in 6-8weeks. Although her TSH level is in the high

end of normal, the target is 1.2 mU/L.

How often should TSH be monitoredafter thyroid replacement is titrated?

Every year or wheneverpt is symptomatic.


What is the risk of malignancyof any thyroid nodule? 5%

What are some warning signs thatsuggest malignancy in thyroid

masses?

Dysphonia, hemoptysis, regionallymphadenopathy, pain, dysphagia,

and a fixed or hard mass.

On thyroid scan, malignantmasses are usually hot or cold? Cold.Physical exam findingswith Graves disease:

Diffuse, soft, enlarged thyroid.Exopthalmos, nervousness, tachycardia,

and heat intolerance are also seen.

What is the most commonform of hyperthyroidism? Graves disease.

Initial management of Gravesdisease symptoms includes.

Start a non-selective beta-blocker (propanolol ornadolol) for tachycardia and tremor immediately, as

antithyroid medications take some time to be effective.

First-line medical managementof Grave's disease:

Antithyroid medications: propylthiouracil (PTU)

methimazole (Tapazole)

These both inhibit thyroid hormone synthesis.

Second-line managementof hyperthyroidism:

Radioactive iodine for thyroid ablation. Thiswill cause lifelong hypothyroidism after

treatment. Consult with endocrine is needed.


What is a major adverse effect ofpropylthiouracil and methimazole? Liver toxicity.What is an adverse effect ofexcessive levothyroxine use? Bone thinning.

Name 3 drugs that may increasemetabolism of levothyroxine:

PhenytoinRifampin

PhenobarbitolCarbamazepine

What is the recommended diagnostictest to distinguish thyroid

malignancy? Fine Needle Biopsy

Which of these would appear as a "cold spot" on thyroid scan?a) Graves disease

b) autonomously functioning adenomac) Hashimoto thyroiditis

d) thyroid cyst. d) thyroid cyst

ANCCBoardReviewThyroidCo-small00center10-2114007

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