Thyroid disorders in everyday care

Chris Vreeland, RN, MSN, NP-c

Georgia Mountain Endocrinology, PC

Introduction• One in ten Americans have a thyroid

disorder• Body’s response to thyroid disorders is

fatigue - most common reason to seek healthcare.

• Women particularly affected by thyroid imbalanceWeightFertilityPregnancyMenopauseOsteoporosis

Thyroid Hormone Action

• Activates nuclear receptors which regulate expression of thyroid hormone-responsive genes:Fetus & neonate: differentiation

of target tissuesChildhood:

differentiation/proliferationAdolescent: role in action of sex

steroids

Thyroid Hormone Action

• Gene expression (continued)

All ages: • Regulates energy production

• Regulates functional /structural proteins

• Regulates action of other hormones - glucocorticoids, mineralocorticoids, growth factors, biologic amines (catecholamines)

Negative Feedback Loop

• Thyroid hormone inhibits pituitary secretion of TSH

• Hypothalamus plays crucial role• TSH very sensitive indication index

of action• TSH & thyroid hormones maintained

in a certain relationship• Modified by TBG (thyroxine-binding

globulin)

Negative Feedback Loop

Hyperthyroidism • Elevated serum thyroid level• Decreased TSH

Hypothyroidism • Decreased serum thyroid levels• Increased TSH

Serum Levels of Thyroid Hormones

• T3 regulates peripheral action of hormone

• T3 & T4 both released from gland

• Peripheral conversion of T4 to T3 occurs in liver and target tissues

• In presence of liver damage, T3 conversion may be low despite good levels of T4

TBG Metabolism

• T4 transported to tissue by TBG• High serum TBG (liver damage,

pregnancy, OCP’s, HRT) lowers serum concentrations of free T4 which decreases amount of substrate (T4) that can be converted to T3

• Indirect measure of TBG abnormality is T3 uptake

Causes of Thyroid Disorders

Hyperthyroidism• Graves’ disease:

• Autoimmune • TSH receptor antibodies

• Thyroiditis: • Sub-acute• Post-partum

• Pituitary tumor - TSH producing

Causes of Thyroid Disorders

Hypothyroidism (High TSH, low T3, T4)

• Hashimoto thyroiditis: • Autoimmune

TPO and thyroglobulin antibodies• RAI: radioactive iodine ablation• Surgery• Antithyroid drugs• Goitrogens: lithium, amiodarone

Normal Hormone Levels

• TSH: 0.4-5.5 MIU/L

• Total T3: 60-181 NG/DL

• Total T4: 4.5-12.5 MCG/DL

• T3 Uptake: 22-35%

Hypothyroidism

SymptomsFatigueWeight gainCold feelingDry hair, nails,

skinHair lossHeavier or

longer menses

ConstipationPeripheral

edemaPeriorbital

edemaBradycardiaHypotension Infertility

Hypothyroidism

• Treatment:

• Hormone replacement (L-T4)

Absorbed from small intestine6-day half-life

• Daily dosing: 0.025-.300 mgs• Branded preparations preferred to

genericSynthroid Levoxyl Tirosint

Hypothyroidism• Treatment

Initial dose:1.7 mcg per kg

Pregnant: may need 1.8 mcg per kgElderly: usually start at lower doses,

esp. with angina or CAD• Monitoring

6-8 weeks after any dose changeAnnually once stableEach trimester in pregnancy

Hypothyroidism• Myxedema Coma

End stage of uncompensated hypothyroidism

Presents most often in elderly and women in winter months

Present in respiratory failure, hypotension, bradyarrythmia, along with serious precipitating illness

Treatment is T4 IV @ 1/10th dose of oral

ICU admit for multi-system failure

HypothyroidismPearls

Most patients reports feeling best with TSH between 1-2

If TSH normal, but patient still not feeling good, think low T3; may need Cytomel (oral T3)

Depression very commonInadequate treatment can contribute to

infertilityLook for recent onset of symptom with

family history of thyroid disease

Hyperthyroidism

SymptomsAnxietyPalpitationsUnintended weight lossDecreased or absent mensesOily skinFine, silky, oily-appearing hairHeat intoleranceExopthalmos (not all cases)Tachycardia

Hyperthyroidism

Treatment• Anti-thyroid drugsMethimazole

Inhibits thyroid hormone synthesis in the thyroid gland

PTU

Inhibits thyroid hormone synthesis in the thyroid gland & inhibits peripheral conversion of T4 to T3

HyperthyroidismDosing:

• Tapazole: 10 mg BID or TID• PTU: only 50 mg tablets available

Usual starting dose: 2 tabs TID; may double dose if necessary

• Both very effective at lowering thyroid hormone levels

• TSH will stay suppressed several month

HyperthyroidismDosing:

Monitor every 4-6 weeksWhen TSH rises, may need to add

T4 (thyroid hormone)Want to leave on ATD’s long

enough to allow TSH receptor antibodies to decrease & induce remission; usually 12-18 months

Plan to withdraw med at 12-18 months to evaluate remission status

Hyperthyroidism

Side effects of anti-thyroid drugs:• Leucocytopenia• Agranulocytosis-most serious• Pernicious anemia• Thrombocytopenia• Hepatic dysfunction• Allergy (discoid rashes)

Evaluate with CMP, CBC, & thyroid hormone levels every 4-6 months

Hyperthyroidism

Radioactive Iodine Ablation

• Administration of I131 iodine by mouth

• Used after TFT’s normal or if unable to control hyperthyroidism with drugs

• Usually destroys gland over 3-6 months

Hyperthyroidism

Radioactive Iodine Ablation• Induces permanent hypothyroidism• May cause post-treatment thyroid

storm (rare)• May cause aggravation of Graves’

eye disease• Pregnancy should be prevented

within 6 months after treatment

Hyperthyroidism

Surgery• When disease state or gland size

can’t be controlled with drugs• When gland causing obstructive signs

Difficulty breathing either supine or upright

-Evaluated by PA & LAT CXRDifficulty swallowing food

-Evaluated by barium swallow

Hyperthyroidism• Thyroid Storm

• Most often with Graves’ disease• Levels same as with Graves’• Cardinal signs:

Temperature 102 to 1050

Profuse sweating

Marked tachycardia (120-140 pulse rate or higher)

Atrial fibrillation• Usually induced by concurrent infection

or surgery on hyperactive gland

HyperthyroidismThyroid storm

• TreatmentPTU orally or by NG tubeTapazole not favored because it does

not inhibit peripheral conversion of T4 to T3

Beta blockade, PO or IVSupportive therapy for fever,

dehydrationPerhaps iodine solution or

corticosteroids

HyperthyroidismGraves’ Eye Disease:• Caused by antibody effect on orbital

tissue• Symptoms include:

EdemaInflammationHypertrophy of extra ocular muscles &

orbital fat• Exopthalmos upper & lower lid retraction,

strabismus, herniated orbital fat

Hyperthyroidism

Graves’ Eye Disease:• Should be stabilized for 6 months

prior to any other treatment modality• Exception is optic neuropathy

caused by strangulation of optic nerve

• Extent of protrusion measured by increase in distance between lateral orbital rim and anterior aspect of eye

Thyroid Nodules

• May be a single nodule or larger of multiple nodules

• 95% benign• More common in women• More likely malignant in men• Increase in size while on T4 therapy

worrisome for malignancy

Thyroid Nodules• Note size, consistency and mobility

on physical exam• Evaluate for tracheal deviation or

esophageal obstruction• Usually TSH suppressed, T3 and T4

levels normal• Antibodies may be present, but

more likely they are not not• Ultrasound best way to diagnose

Thyroid NodulesTreatment• Multinodular gland without dominant

nodule: T4 to shrink if TSH not suppressed

• Single nodule 1 cm or greater: fine needle aspiration biopsy

• Enlarging nodule despite “good” dose of T4 or indeterminate or malignant result from FNA indicates need for surgery

Thyroiditis

• Most common cause: chronic autoimmune thyroiditis or post-partum thyroiditis

• Next is sub acute thyroiditis

• More rare: acute suppurative thyroiditis

Thyroiditis

Post-partum thyroiditis• May occur anytime in the first year,

but most common in first 3 months• Usually have hyperthyroid

symptoms first, followed by hypothyroid findings

• Gland usually enlarged• Will not have other markers for

inflammation: fever, tenderness, high sed rate

Thyroiditis

Post-partum thyroiditis• Usually spontaneously resolve• May need temporary medication

support for symptomsBeta blockers for tachycardiaTranquilizers for anxietyT4 for hypothyroidism

• Can progress to permanent hypothyroidism

Thyroiditis

Sub acute• Usually follows viral illness• Gland is swollen, tender• Sed rate elevated >50mm/hour• May have fever, even fairly mild• Leucocytosis• Follows usual pattern of transient

hyperthyroidism, then hypothyroidism, then euthyroid

Thyroiditis

Sub acute• Treatment:

SymptomaticNSAIDS for pain, feverPrednisone for severe pain

unrelieved by aboveBeta blockers for hyper phaseThyroid replacement for hypo phaseResolve spontaneously

Questions?

Thank you!