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45 terms

Endocrinology (Thyroid)

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What is a goiter?
Any visibly or palpably enlarged thyroid. It can be DIFFUSE (Graves dz, Hashimoto's thyroiditis, subacute thyroiditis, endemic goiter), HETEROGENOUS (multinodular goiter), or SOLID NODULE (benign nodule vs. CA)
What is the 1st line screening tests for thyroid disorders?
TSH (looking at pituitary function) and Free T4 (free T4 doesn't change relative to binding proteins, so it's a little more helpful)
What can an ultrasound help you determine?
anatomy of the gland (size of a nodule, etc)
If there is no uptake of iodine into the thyroid gland, this indicates what? Does it have a good or bad prognosis?
Indicates a cold nodule, which is more worrisome than a hot nodule because cold nodules often contain malignancy
What is the most common form of hypothyroidism?
Hashimoto's thyroiditis (autoimmune); it is a primary cause of hypothyroidism
What are the SxS hypothyroidism?
Fatigue
**Dry skin
Myalgias/cramps
**Hair loss
**Brittle nails
Abnormal menses
**Cold intolerance
Constipation
Depression
Decreased appetite
**Wt gain
Goiter
What is a PE specific finding that is indicative of hypothyroidism?
abnormal DTR --> delayed relaxation phase (normal upstroke, then slow relaxation); felt best in brachial and achilles
Untreated hypothyroidism can lead to what condition?
Myxedema
What are SxS of myxedema?
Large tongue
Carotenemic skin color
Course thickened edematous skin
Slow/slurred speech
Mental apathy
Cardiomegaly
Hypothermia
Bradycardia
Anemia
Hyponatremia
Hypoglycemia
Your pt has hypothyroidism. You order labs to look at TSH and Free T4. How can you determine whether they have primary or secondary hypothyroidism?
Both with have decreased Free T4. The difference is that primary will have elevated TSH, whereas secondary has decreased or low normal TSH.
How do you treat hypothyroidism?
Levothyroxine (Synthroid, Levothroid)

Monitor TSH/Free T4 to determine if dose is appropriate
For secondary hypothyroidism, only use free T4 since pituitary not functioning
(T/F): Use Levothyroxine (Synthroid) until TSH and Free T4 levels are normal, and then you can discontinue use of the drug.
F. Tx is long-term because thyroid failure is usually permanent
What is the most common cause of hyperthyroidism?
Graves dz (autoimmune); antibodies target TSH receptors and increase production/release of thyroid hormone
What are other causes of hyperthyroidism?
Toxic Nodular Goiter (multinodular)
Toxic Adenoma (Plummer's dz)
Thyroiditis (lymphocytic vs. subacute)
Iodine induced (Jodbasedow dz)
Thyrotoxicosis factitia
What are SxS of hyperthyroidism?
**Wt loss
**Heat intolerance
Palpitations
Nervousness/Tremor
Sleep disturbance
Menstrual changes (lighter/less frequent)
Increased Appetite
Goiter
**Exopthalmos
**Dermopathy (pretibial myxedema,
onycholysis)
Muscle weakness
What will TSH, Free T4, and Free T3 levels look like in someone with hyperthyroidism?
Suppressed TSH
Elevated Free T4/T3
When performing a thyroid scan, what are you looking for?
Homogeneity vs heterogenity
determining hot vs. cold nodules
What will be the findings of a thyroid scan and uptake in a pt with Grave's dz?
Scan --> homogenous
Uptake --> increased
How do you treat a pt with Grave's dz?
PTU/methimazole
Radioactive iodine (131I)
Surgery
What is the Tx of choice for someone with Toxic Nodular Goiter?
131I is Tx of choice (large doses!)
?Surgery
Your pt has hyperthyroidism and is pregnant. What do you NOT want to treat her with?
radioactive iodine --> CONTRAINDICATED IN PREGNANCY!

Therefore, always check hCG levels before treating pt w/ 131I
What can you give a pt with hyperthyroidism experiencing extreme cardiac symptoms?
Beta blockers (ie propranolol) --> slows HR
What can you give a pt before surgery to prevent thyroid storm?
Beta blockers + PTU
How might hyperthyroidism present in the elderly?
apathetic hyperthyroidism (opposite presentation)
What are the manifestations of thyroid storm?
Fever
Cardiac abnormalities (arrhythmias, CHF)
Diaphoresis
Altered mental status (confusion, delirium, seizure, coma)
Differentiate autoimmune vs. subacute thyroiditis
Both have SxS of hyper or hypo

Autoimmune --> painLESS, firm slightly irregular, assoc. w/ antibodies in bld, typically leads to permanent hypothyroidism

Subacute --> painful (esp along jawline), inflammatory in nature, usually self limited
What are risk factors for developing thyroid nodules?
Increasing age
Female
h/o head/neck irradiation
FHx of thyroid CA
Iodine deficiency
What are risk factors for developing malignancy of a thyroid nodule?
Nodule in pt <20 or >70
male>female
H/o neck irradiation
Personal or FHx of Thyroid CA
Environmental toxins
What nodule characteristics are worrisome for malignancy?
Rapidly enlarging nodule
Dysphagia or hoarseness
Firm, hard or fixed
Lymphadenopathy
Male gender
What is the value of a thyroid ultrasound?
It has a high sensitivity for # and size of nodules, and it's excellent for following nodules long-term
What findings on an U/S are suggestive for malignancy?
Central microcalcifications
Irregular margins
Intranodular vascular pattern
Hypoechogenecity
Incomplete peripheral halo
When is Fine Needle Aspiration (FNA) indicated?
ALL palpable nodules and incidentalomas > 10mm or with risk factors for malignancy
When is radionuclide scanning used?
It's generally not necessary due to high quality of U/S
Are hot or cold nodules more common?
only 10% are hot
90% are cold or warm
You have just detected a thyroid nodule on your pt. What is a very important question you want to ask them?
"Do you have a h/o head or neck irradiation?"
What is the most common type of Thyroid CA?
Papillary (76%); also the least aggressive
How do you treat thyroid CA?
(Near-total) thyroidectomy
Post Surgical Total Body I-131 Scan (P & F)
High Dose I-131 ablation if + Scan or large tumor >2cm(P& F)
Scans done Q 1-3 years depending on duration from initial treatment (P&F)
Lifetime Treatment w/ levothyroxine
Lobectomy may be acceptable treatment for Papillary tumors <1 cm
What is the prognosis for thyroid CA?
P&F --> excellent
Medullary --> variable (70-80%); assoc. w/ MEN syndrome
Anaplastic --> poor (<5%)
What are 3 thyroid hormone drugs?
Levothyroxine
Liothyronine
Thyroid Extract
What is Liothyronine?
A thyroid hormone drug that acts same as T4 (4x more potent than T4 and less protein bound)
What is Thyroid Extract "Armuor Thyroid"?
A thyroid hormone combination drug (4:1, T4:T3)
What is a serious AE of antithyroid drugs?
agranulocytosis
What is the MOA for Methimazole (Tapazole)?
Prevents synthesis (not secretion) of thyroid hormones
What is the MOA for Propylthiouracil (PTU)?
Prevents synthesis (not secretion) of thyroid hormones AND inhibits conversion of T4 to T3
(For this reason drug of choice in Thyroid Storm)
What is the MOA for RAI?
It destroys thyroid tissue; consider risk of iatrogenic hypothyroidism