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Thyroid Disorders Flashcards

1
Q

Peak of hyperthyroidism

A

Ages 20-40 but can also occur over 60

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2
Q

Risk factors of hyperthyroidism

A

-Female sex
-Family hx of thyroid disease
-Age <40 or >60
-Have autoimmune disorders (type I DM, pernicious anemia)
-Consume large amounts of iodine

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3
Q

Which T level is more biologically active?

A

T3 (20-100 times more active)

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4
Q

Subjective findings of hyperthyroidism

A

Anxiety, nervousness, diaphoresis, fatigue, heat intolerance, palpitations, weight loss, insomnia

Fullness/pressure in the neck with enlarged thyroid

Exercise intolerance, tremors, lower extremity edema, weight loss in presence of an increased appetite, menstrual irregularities, frequent bowel movements or diarrhea, exertion dyspnea

Eye complaints - blurred vision, proptosis, photophobia, double vision

Poor concentration, extremely irritable, emotionally labile

Older patients may present with vague symptoms

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5
Q

Physical exam findings of hyperthyroidism

A

Older adult - FTT

HEENT: lid lag, conjunctiva inflammation, decreased visual acuity, exophthalmos, excessive lacrimation

Thyroid may be enlarged, nodules may be palpable, and a bruit may be heard over thyroid gland

Cardiac: tachycardia, irregular pulse, systolic murmurs, widening of pulse pressure

Skin, hair, nails: edema, thinning hair, skin velvety to touch, increased pigmentation, spider angiomas, vitiligo, onycholysis, splitting/spooning of nails, clubbing of digits

Neuro: decreased strength in extremities, fine tremor, hyperreflexia - especially noticeable in achilles tendon

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6
Q

Initial testing results - TSH, FT4, FT3

A

TSH <0.35, elevated T4>12.5, free T4 >1.8

If T4 is normal, order T3 level

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7
Q

Medications that may alter laboratory results in hyperthyroidism

A

Anabolic steroids, androgens, estrogens, heparin, iodine-containing compounds, phenytoin, rifampin, and salicylates

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8
Q

Other testing considerations for hyperthyroidism

A

-Nuclear scintigraphy with radio labeled iodine (123I) or technetium (99Tc) - helps in assessing functional status of thyroid gland
-24-hour radioactive iodine uptake (RAIU) - identifies areas of increased/decreased thyroid function; “hot and cold spots”
-US of thyroid - assists in differentiating cyst from nodule
-Fine-needle biopsy (PREFERRED diagnostic technique to evaluate thyroid masses)

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9
Q

Thyrotoxicosis usually seen with

A

Suppressed TSH; if high levels of TSH, consider a rare pituitary tumor

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10
Q

Common causes of hyperthyroidism

A

-Grave’s disease (70%)
-Toxic nodular or multi nodular goiter, toxic thyroid adenoma
-Thyroiditis (usually transient)
-Excessive thyroid hormone intake
-Excessive iodine intake

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11
Q

T4 levels may be elevated in

A

-Acute illnesses
-Presence of elevated estrogen levels
-Hyperemesis
-Familial thyroid hormone binding abnormalities, autoimmunity

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12
Q

Medications that may increase T4 levels

A

Amiodarone, amphetamines, clofibrate, glucocorticoids (high doses), heparin, heroine, levothyroxine, methadone, perphenazine

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13
Q

Medications that may decrease TSH levels

A

Dopamine, high-dosage glucocorticoids

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14
Q

Possible therapies for hyperthyroidism management (may not need if transient or mild)

A

-Radioiodine therapy (>20 years old or failed thioamide therapy)
-Beta-blocker for heart rate control (avoid in asthma, CHF, pregnancy) and symptom relief
-Thiomide therapy in younger or pregnant patients (methimazole [MMI, tapazole] or PTU)
-Thyroidectomy (if airway compromise from enlarging goiter)
-Antibiotic therapy if suppurative type of thyroiditis

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15
Q

Thyroid function tests are monitored

A

At least twice a year

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16
Q

Initial thyroid treatment should be evaluated at

A

1 month and at 3 months or more frequent if patient is symptomatic

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17
Q

Therapy duration of antithyroid medications

A

3-12 months

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18
Q

After radio iodine therapy, thyroid function tests should be performed at

A

6 weeks, 12 weeks, 6 months, and annually thereafter

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19
Q

Subclinical hyperthyroidism levels

A

Undetectable TSH levels and normal T4 and T3 levels

Refer to endo

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20
Q

Thyroid storm (thyrotoxicosis) is a potentially life-threatening condition that can be the result of

A

-major stress in someone with uncontrolled hyperthyroid
-associated with radioactive iodine therapy in Graves disease (>1 week after) (rare)
-hyperfunctioning thyroid
-over medication with thyroid hormone

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21
Q

Sudden onset of thyroid storm causes

A

Tachycardia, arrhythmias - leading to:
-HF
-pulmonary edema
-fever (>100.5)
-diarrhea
-nervousness
-confusion
-coma
-death

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22
Q

Postpartum thyroiditis is treated symptomatically with

A

Beta-blockers (caution in BF) or thyroid hormone therapy

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23
Q

Toxic nodule treatment

A

-beta-blocker therapy followed by radio iodine ablation
-surgical excision

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24
Q

Toxic multinodular goiter treatment

A

-beta-blocker therapy followed by radio iodine ablation (may require repeat)
-surgical excision

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25
Thyroid nodules are palpable if
0.5-1 cm
26
Risk factors of thyroid nodules/cancer
-hx head/neck radiation -family hx -age <20 or >60 -male gender -history of MENS-2 or medullary thyroid cancer -Cowden disease -Garner syndrome -Familial polyposis
27
Thyroid cancer is characterized by
Usually enlarging, painful (associated with hoarseness, dysphonia, dysphagia, or dyspnea), pathologic fractures, thoracic outlet syndrome, symptoms of hyperthyroidism
28
Thyroid cancer is characterized by thyroid nodules that increase during treatment with
Thyroid replacement therapy -may be hard, fixed; or soft, or fluctuant
29
Diagnostic testing for thyroid nodules
-US (evaluate cystic vs. solid components) -radionucleotide scan (determine hot [hyperfunction] or cold [hypofunction] nodules) -fine-needle aspiration if >1-1.5 cm if risk factors present for malignancy, hypo echoic or complex (solid and cystic)
30
Thyroid malignancy on US shows
Increased vascular flow, hypo echoic nodules, irregular margins, absent halo, micro calcifications, taller (height) or lesion > width
31
Benign features seen on thyroid US
Simple cyst, spongiform appearance (multiple micro cysts)
32
Thyroglobin level is a marker for
Recurrence of thyroid cancer
33
Patient education for patients undergoing radioactive iodine therapy or scanning
-no kissing, sharing food for 5 days -wash all dishes in dishwasher -no close contact with children <8 or pregnant women for 5 days -no breastfeeding -flush toilet twice after urinating (and wash hands) -report nervousness, tremors, or palpitations
34
Most common cause worldwide of hypothyroidism
Iodine deficiency
35
Primary cause in the U.S. of hypothyroidism
Autoimmune processes
36
Hypothyroidism occurs 2-8 times more commonly in
Women than men -higher incidence in whites
37
Iatrogenic (medication) causes of hypothyroidism
Amiodarone, dopamine, lithium, interferon-a, thalidomide, stavudine
38
Most common form of autoimmune thyroid disease, with average onset from 30-60 years old
Hashimoto's thyroiditis or primary hypothyroidism
39
Iatrogenic hypothyroidism occurs
Following treatment with radioactive iodine or surgery
40
Secondary hypothyroidism occurs due to
Failure of the pituitary gland to secrete adequate amounts of TSH
41
Tertiary hypothyroidism occurs due to
Inadequate secretion of TRH by the hypothalamus or failure of TRH to activate its cognate receptors within the pituitary (peripheral resistance)
42
Central hypothyroidism occurs due to
Direct impingement by tumors on the pituitary gland or the hypothalamus
43
In hypothyroidism, production of T4 is inadequate, causing the thyroid gland to enlarge which stimulates
Hypertrophy and hyperplasia of the thyroid gland, resulting in goiter
44
Autoimmune form of hypothyroidism can result, causing
Body pathologically recognizes thyroid antigens as foreign Leads to chronic immune response involving lymphocytic infiltration, vasculizaiton, and fibrosis of the parenchyma Eventually causes atrophy of the thyroid follicles
45
Destructive thyroid inflammation may occur due to
Immune cross-reactivity following viral infections
46
Low levels of thyroid hormones effect every body system, resulting in an overall decrease in
Basal metabolic rate Abnormalities in lipid metabolism GI slowed in gastric emptying and intestinal transit time, impaired digestion, deficiencies in vitamin B12, iron, folate
47
Endocrine abnormalities of hypothyroidism
-menstrual irregularities, infertility, delayed onset of puberty -insulin resistance -decreased erythropoiesis
47
Subjective early classic symptoms of hypothyroidism
Fatigue, dry skin, slight weight gain, cold intolerance, constipation, heavy menses
47
Accumulation of hydrophilic proteoglycans within interstitial space causes increase in
Interstitial fluid - pleural, cardiac, and peritoneal effusions
48
Later symptoms of hypothyroidism
Very dry skin, coarse hair, loss of lateral eyebrows, alopecia, hoarseness, continued weight gain, slight impairment in mental ability, depression, decreased libido, hypersomnia
49
Physical exam of hypothyroidism
General: facial puffiness, periorbital edema, dry, coarse, thick skin/hair, brittle nails, slow speech, bradykinesia, hoarseness, large tongue, thinning of eyebrows Thyroid may be enlarged/tender or not palpable CV: bradycardia, lateralized PMI, mild diastolic HTN GI: diminished or hypoactive BS Neuro: hypotonic and hyporeflexic with a prolonged relaxation phase and/or ataxia, edema
50
Which T4 level is preferred?
Free T4 rather than total T4 Alterations in hormone protein binding may result in large fluctuations in total serum T4 level
51
Initial testing results for symptomatic or high risk patients of hypothyroidism (e.g., DM, autoimmune disorders, depression, obesity, etc.)
-elevated TSH and decreased free T4 -if TSH is low, normal, or insufficiently elevated in presence of low T4 values, central hypothyroidism caused by hypothalamic or pituitary disease should be excluded
52
Subsequent testing of hypothyroidism
-CBC - anemia -chemistry panel -UA -lipid panel - elevated LDL and triglycerides -ECG -CXR -TPO antibody/antithyroglobulin antibody -thyroid US and possible scan if nodules noted -may need referral for FNA
53
Antimicrosomal antibody (anti-TPO antibody) is diagnostic for
Hashimoto's thyroiditis when titers are high (1:400) Antithyroglobulin antibody is also increased, but it is not as specific for Hashimoto's
54
Treatment for hypothyroidism
Synthroid 1.6 mcg/kg/day for full replacement
55
Patients who are older or have CAD should begin hypothyroidism treatment with
1/2 the expected replacement dose or 12.5-25 mcg/day PO, increasing the dose gradually once every 4-6 weeks
56
Synthroid dosing is best done
In the morning to avoid nighttime insomnia
57
What may alter dosing requirements in either direction of the hypothyroid patient?
Concurrent severe illness or major surgery Pregnancy - increase replacement therapy
58
After therapy is initiated for hypothyroidism, check patient's TSH level in
6 weeks
59
Target TSH level
0.3-3.0 mcg/dL
60
Once a stable dose of Synthroid is established, check TSH level
Biannually or annually
61
Endocrinology specialist is recommended if
-a patient has cardiac disease, symptoms of myxedema, or central (secondary or tertiary) hypothyroidism -signs/symptoms of myxedema, chest pain, or thyrotoxicosis occur after starting HRT -patients have severe illness or those who present with unusual or confusing lab findings -patients <18 years old -pregnant/postpartum patients -those taking lithium or amiodarone
62
Treatment may affect levels of
Phenytoin, lithium, TCAs, estrogen, digitalis, anticoagulants, and indomethacin
63
Medications that interfere with therapy
Iron, calcium carbonate, aluminum hydroxide, sucralfate, and tube feedings
64
Diet education
Low-fat, high-fiber foods Increase intake of raw fruits/vegetables, bran or high-fiber cereals and breads, and add unprocessed bran (2 tbsp/day) to cereal or liquids Bulk-forming laxative containing psyllium may be taken daily Increase water intake to 6-8 glasses/day
65
The American Thyroid Association recommends treating subclinical hypothyroidism when
-TSH level >10 -antithyroid antibodies are present -serum lipid levels abnormal -patient smokes -patient is symptomatic at this TSH level However, data regarding the treatment of asymptomatic patients with TSH between 4.5-10 are inconclusive
66
If the decision is made not to treat patients, evaluate at
6-12 month intervals for evidence of worsening thyroid function A low dose can be given (0.5-1.0 mcg/kg)

Endocrine (5 decks)

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