Thyroid Hormone

Question 1

Thyrotoxicosis is what?

Answer 1

Systemic syndrome d/t exposure to excessive thyroid hormone

Question 2

Hyperthyroidism refers to those forms of thyrotoxicosis caused by what?

Answer 2

excessive production of thyroid hormone d/t stimulus or autonomous thyroid function

Question 3

Hyperthyroidism Etiology - Hyperthyroidism

Answer 3

Antibody mediated stimulation of thyroid tissue (graves disease - younger women)
Excessive secretion of TSH
Autonomously functioning Thyroid tissue (Toxic multinodular goiter, toxic adenoma, iodine exposure, struma ovarii, metastatic thyroid cancer)

Question 4

Nonhyperthyroid thyrotoxicosis - Etiology

Answer 4

Ingestion of exogenous thyroid hormone (meds, supplements, meat)
Inflammation (subacute thyroiditis, autoimmune thyroiditis)

Question 5

Graves Diseases is an autoimmune process

Answer 5

Thyroid stimulating immunoglobulins bind to/activate TSH receptor > thyroid hormone secretion, gland growth

Question 6

Graves Disease is characterized by what?

Answer 6

Diffusely enlarged thyroid
ophthalmopathy
Exophthalmos
EOM involvement
vision loss
Dry, gritty eyes
pain
diplopia

Question 7

Hyperthyroidism Clinical Manifestations

Answer 7

Anxiety
Emotional lability
Weakness
Tremor
Palpitations
Tachycardia
Heat intolerance
Increase perspiration
Hyperreflexia
Increased appetite
Nervousness
Weight loss
Warm, moist skin
Thin, fine hair
Exophthalmos

Question 8

Hyperthyroidism in elderly may present differently with s/sx like

Answer 8

weight loss
tachycardia
constipation

Question 9

Hyperthyroidism Diagnosis
Physical Exam components

Answer 9

Thyroid (size, tenderness, symmetry, nodularity)
Pulmonary, Cardiac & Neuromuscular function
Peripheral edema
Optho signs
periorbital myxedema

Question 10

Hyperthyroidism Diagnosis
Ultrasound can show?

Answer 10

anatomy
lesions
nodules
goiters
masses
inflammation
flow

Question 11

Hyperthyroidism Diagnosis
TSH initial screening test
TSH will what? d/t what?
If TSH low check what?
Sometimes T4 is normal but T3 is what?

Answer 11

low; elevated levels of T3 & T4 inhibiting secretion of TRH by hypothalamus & TSH by pituitary
free T3&T4
elevated

Question 12

Hyperthyroidism Diagnosis
Additional Labs to help diagnosis

Answer 12

Thyrotropin receptor antibody (TRAb)
Radioactive iodine uptake (RAIU)
Thyroidal blood flow via US

Question 13

If TSH is low and Free T4 is High it is?

Answer 13

Thyrotoxicosis

Question 14

If TSH is low and Free T4 is normal is is?

Answer 14

T3-thyrotoxicosis
Subclinical thyrotoxicosis
Nonthyroidal illness

Question 15

If TSH is normal and Free T4 is elevated it can be?

Answer 15

TSH-secreting adenoma
Pituitary resistance to thyroid hormone
Generalized resistance to thyroid hormone
Familial dysalbuminemic hyperthroxinemia

Question 16

If TSH is normal and Free T4 is normal it is?

Answer 16

normal

Question 17

Hyperthyroidism Management
Beta blockers for who? why?

Answer 17

all (ameliorate symptoms of hyperthyroidism caused by increased beta-adrenergic tone

Question 18

Hyperthyroidism Management
In Graves disease possible treatments are?

Answer 18

Antithyroid drugs (Methimazole, Propylthiouracil (PTU)
Radioactive Iodine
Thyroidectomy

Question 19

Antithyroid drugs
Inhibit function of thyroid peroxidase which does what?
1st go to med? for how long?
What med is safer in pregnancy?
Side effects include?

Answer 19

reduces oxidation & organoification of iodine
methimazole (MMI) x 12-18 mo)
PTU (inhibits peripheral conversion of T4 > T3)
agranulocytosis, skin rash, elevated LFTs, vasculitis

Question 20

Thyroid Storm Clinical Manifestations

Answer 20

Tachycardia
CHF
Hyperthermia
Agitation
Delirium
Psychosis
Stupor
Severe N/V or diarrhea

Question 21

Thyroid Storm Precipitating Factors

Answer 21

Long Standing untreated hyperthyroidism
Infection
Trauma
Surgery
Acute Iodine Load

Question 22

Thyroid Storm Differential Dx

Answer 22

Sepsis
Cocaine use
PAID
Pheochromocytoma
Neuroleptic malignant syndrome
Hyperthermia

Question 23

Thyroid Scoring system results of >/=45 indicates?
25-44 is suggestive of?
< 25 is suggestive of?

Answer 23

highly suggestive of thyroid storm
impending storm
unlikely to represent thyroid storm

Question 24

Thyroid Storm Management
PTU dosing?
MMI dosing?
Propranolol dosing?
Iodine dosing?
Hydrocortisone dosing?

Answer 24

500-1000mg load, then 250mg q4h
60-80 mg/d
60-80mg q4h
5 drops PO q6h
300mg IV load, then 100mg q8h

Question 25

Subclinical hypothyroidism is characterized by what?

Answer 25

Elevated TSH & normal T4

Question 26

Overt Hypothyroidism is characterized by what?

Answer 26

TSH > 10 mlU/L + subnormal T4

Question 27

Primary Hypothyroidism Etiology can be from?

Answer 27

Autoimmune disease (Hashimoto's Thyroiditis) Drugs (lithium, amiodarone, interferon) Iatrogenic (post radiation, surgery) Congenital (inborn error of hormone metabolism) Iodine Deficiency (rare in US)

Question 28

Secondary Hypothyroidism Etiology can be from?

Answer 28

Pituitary tumor pituitary surgery/ XRT Craniopharyngiomas

Question 29

Hashimoto's Thyroiditis pathophysiology

Answer 29

Infiltration of thyroid by sensitized T lymphocytes & serologically circulating thyroid autoantibodies

Question 30

Hashimoto's Thyroiditis occurs with increased frequency among other autoimmune disorders such as?

Answer 30

DM I RA MG primary adrenal failure celiac disease SLE

Question 31

What are the main Clinical Manifestations of Hypothyroidism

Answer 31

Intolerance of cold temperatures Dry, thick skin Delayed DTR Carpal Tunnel Syndrome

Question 32

What are other Clinical Manifestations of Hypothyroidism?

Answer 32

Fatigue Weight Gain Coarse or thin hair brittle nails constipation bradycardia Puffy hands, face, feet (myxedema) Menorrhagia/amenorrhea +/- goiter

Question 33

Differential Dx for hypothyroidism

Answer 33

Anemia Depression Constipation Hypothermia Fibromyalgia

Question 34

Diagnosis of Hypothyroidism is done how?

Answer 34

TSH (elevated) Free T4 (low)

Question 35

Hypothyroidism Management Primary Hypothyroidism & TSH levels > 10 mlU/L

Answer 35

Start Levothyroxine 1.6mcg/kg/d

Question 36

In elderly w/ CAD how is hypothyroidism managed?

Answer 36

Start a lower dose & titrate gradually (20-25% less per kg/d; usually 12.5-25mcg/d)

Question 37

With pregnant patients who have hypothyroidism, what precaution must be made?

Answer 37

A need for transient increase in their dose.

Question 38

How often should dosage be titrated for hypothyroidism?

Answer 38

q4-8 wks (usually by increments of 12.5-25mcg)

Question 39

TSH goal is what?

Answer 39

between 0.45-4.12

Question 40

Myxedema is what?

Answer 40

thickened, nonpitting edema to soft tissues in markedly hypothyroid state

Question 41

Myxedema Coma is often precipitated by what?

Answer 41

infection meds environmental exposure other metabolic-related stresses

Question 42

Management of Myxedema Coma Hypothyroidism? Alternative?

Answer 42

Large inital IV dose of 300-500 mcg T4, if no response ad T3 Initial IV dose of 200-300mcg T4 plus 10-25mcg T3

Question 43

Management of Myxedema Coma Hypocortisolism

Answer 43

IV hydrocortisone 200-400 mg daily (divided by 4 doses)

Question 44

Management of Myxedema Coma Hypoventilation

Answer 44

Dont delay intubation and mechanical ventilation too long

Question 45

Management of Myxedema Coma Hypothermia

Answer 45

Blankets, no active warming

Question 46

Management of Myxedema Coma Hypotension

Answer 46

Cautious volume expansion with crystalloid or whole blood

Question 47

Management of Myxedema Coma Hypoglycemia

Answer 47

Glucose admin

Question 48

Management of Myxedema Coma Precipitating even

Answer 48

Identification and elimination by specific treatment, liberal use of abx

Question 49

Euthyroid TSH Free T4 Free T3

Answer 49

Normal Normal Normal

Question 50

Primary Hypothyroidism TSH Free T4 Free T3

Answer 50

High Low Normal or Low

Question 51

Hyperthyroidism TSH Free T4 Free T3

Answer 51

Low High or normal High

Question 52

Subclinical Hypothyroidism TSH Free T4 Free T3

Answer 52

High Normal Normal

Question 53

Subclinical Hyperthyroidism TSH Free T4 Free T3

Answer 53

Low Normal Normal

Question 54

TSH-mediated Hyperthyroidism TSH Free T4 Free T3

Answer 54

Normal or High High High