Courses in Therapeutics and Disease State Management Epidemiology and Classification 12 of the US population will experience thyroid disease in their lifetime Thyroxine T4 is the predominant hormone secreted by the thyroid gland ID: 1036695
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1. Endocrinology:Thyroid DisordersCourses in Therapeutics and Disease State Management
2. Epidemiology and Classification12% of the U.S. population will experience thyroid disease in their lifetimeThyroxine (T4) is the predominant hormone secreted by the thyroid glandThyroid activity is under the control of thyrotropin (TSH) through the negative feedback system of the hypothalamic–pituitary–thyroid axis Deficiencies in T4 (hypothyroidism) or T4 in excess (thyrotoxicosis) causes symptoms in almost all of the body’s major systems.
3. Laboratory Tests Used in the Diagnosis and Treatment of Thyroid Disease (Slide 1 of 2)Thyroid Stimulating Hormone (TSH)ThyrotropinProduced by the anterior pituitary gland in response to TRH (thyrotropin-releasing hormoneStimulates secretion of T4 (thyroxine) and T3 (triiodothyronine) from the thyroidRegulated by negative feedback inhibition by T4 and T3Primary test for screening and monitoring response to thyroid replacement therapyTotal T4Total Thyroxine is free + boundT4 is primarily bound (albumin, prealbumin, and thyroxine binding gloubulin (TBG)); remaining free fraction is activeAffected by binding abnormalitiesAbnormal levels may indicate binding protein abnormalitiesFree T4 Represents active T4Direct measurement is more reliable than total levelsPrecursor of T3Measure of thyroid functionLink: Table on Thyroid Function Test Results in Different Thyroid ConditionsLink: Figure of Hypothalamic-Pituitary-Thyroid Hormone Axis
4. Laboratory Tests Used in the Diagnosis and Treatment of Thyroid Disease (Slide 2 of 2)Triiodothyronine (T3)Produced from peripheral de-iodination of T4Useful in monitoring thyrotoxicosisThyroid Stimulating Hormone Receptor Antibody (TRaB)Autoantibodies to TSH receptor on thyroid glandMimics TSH and stimulates TSH receptor (confirms Graves Disease)Thyroperoxidase Antibody (TPOAb)Antibodies against thyroid peroxidase in thyrocytesPresence identifies autoimmune disordersPredicts conversion of subclinical hypothyroidism to overt hypothyroidismThyroglobulin Antibody (TgAb)Used as an adjunct to TPOAb to diagnose Hashimoto’s Thyroiditis Used in monitoring thyroglobulin levels in thyroid cancerLink: Table on Thyroid Function Test Results in Different Thyroid ConditionsLink: Figure of Hypothalamic-Pituitary-Thyroid Hormone Axis
5. Thyroid DisordersHypothyroidismSymptomsDry skinCold intoleranceWeight gainConstipationDepression/loss of ambitionFatigue/loss of energyMuscle cramps/stiffnessInfertility/Heavy mensesHyperlipidemiaThyrotoxicosisSymptomsAnxietyHyperreflexiaPalpitationsEmotional labilityHeat intoleranceWeight loss with increased appetiteAmenorrhea/Menstrual disorders
6. HypothyroidismPrimary hypothyroidismHashimoto’s diseaseIatrogenic hypothyroidismIodine deficiencyEnzyme defectsThyroid hypoplasiaGoitrogensSecondary hypothyroidismPituitary diseaseHypothalamic disease
7. Hypothyroidism: Autoimmune Thyroiditis (Hashimoto’s Disease) (Slide 1 of 2)SJ is a 44 year old female with no significant past medical history. During a wellness visit with her primary care physician, she asks if there are any vitamins or supplements she can take for her skin, nails, and hair. She notes that her skin has become unusually dry and her hair is coarse and brittle. She endorses a lack of energy lately but had attributed this to the “extra pounds” she has put on over the last year. She denies any changes in her diet and her only medication is an over-the-counter laxative she takes a few times a week as needed. What screening tests can be done to screen for thyroid disease as a cause of her symptoms?
8. Hypothyroidism: Autoimmune Thyroiditis (Hashimoto’s Disease) (Slide 2 of 2)ScreeningTSH (TSH with reflex free T4)DiagnosisT4 (low-normal)Elevated Thyroperoxidase and Thyroglobulin antibodiesSubclinical hypothyroidismTSH 5-10mIU/mlOvert hypothyroidismTSH >10mIU/mlLink: Table covering Thyroid Function Test Results in Different Thyroid ConditionsEvidence supports screening in patients with:Autoimmune diseasePernicious anemia1st degree relative with autoimmune thyroid diseaseRadiation to the thyroid glandA history of thyroid surgery or abnormal thyroid examPsychiatric disordersTaking amiodarone or lithiumDisorders associated with thyroid diseaseReference: Endocr Pract. 2012; 18:6
9. Hypothyroidism: ManagementSubclinical hypothyroidismPositive antibodiesCardiac diseaseSymptomaticLevothyroxine 25-75 mcg/dayOvert hypothyroidismFull replacement dose is approximately 1.6mcg/kg of ideal body weight (typically 125mcg/day)Lower starting dosesElderly: 50 mcgCoronary heart disease: 12.5-25mcgDosage adjustmentsBased on TSH 6 weeks after initiation, dose adjustments, or change in manufacturerTarget is TSH in normal rangeAdjustments made in increments of 12.5-25 mcgSlower in elderly or underlying cardiac diseaseStable patients every 12 monthsLink: Table covering Thyroid Preparations Used in the Treatment of Hypothyroidism
10. Concept ReviewSJ returns 1 week later for follow-up on lab work.TSH: 9.3 mIU/mlTPO Antibodies are elevatedShe is diagnosed with subclinical hypothyroidism and is started on levothyroxine 25mcg QAM.
11. Hypothyroidism: Patient Education(Slide 1 of 2)Administration30-60 minutes on empty stomach first thing in the morningAdverse EffectsThyrotoxicosisHeart failureAngina pectorisMyocardial infarctionOsteoporosisHypersensitivity rare with synthetic T4
12. Hypothyroidism: Patient Education (Slide 2 of 2)Selected Interactions Affecting AbsorptionBile acid sequestrants SucralfateMultivitaminsAntacidsFerrous sulfatePhosphate bindersCalcium saltsChromium picolinateCharcoalOrlistatCiprofloxacinH2 receptor antagonistsProton pump inhibitorsGrapefruit juiceEspresso coffeeHigh fiber dietSoy
13. Thyrotoxicosis (Slide 1 of 5)Link: Table on Differential Diagnosis of ThyrotoxicosisLink: Photos illustrating features of Graves’ DiseaseGraves’ DiseaseThyrotoxicosisExophthalmosLid lagPretibial myxedemaThyroid acropachy
14. Thyrotoxicosis (Slide 2 of 5)ScreeningTSH (TSH with reflex free T4)T4/T3Radioactive iodine uptake (RAIU) testThyroid Stimulating Hormone Receptor Antibody DiagnosisTSH (undetectable-low)T4/T3 highIncreased RAIUPositive antibodiesLink: Table covering Thyroid Function Test Results in Different Thyroid Conditions
15. Thyrotoxicosis (Slide 3 of 5)ManagementBeta-blockersLink: Table covering Treatments for Hyperthyroidism Caused by Graves’ Disease
16. Thyrotoxicosis (Slide 4 of 5)ThioureasMethimazole (MMI) 15-60mg daily in 3 divided dosesPropylthiouracil (PTU) 300-600 mg daily in 3 divided dosesMethimazole is the drug of choiceException: 1st trimester of pregnancyDoses tapered monthlyMonitoringHepatotoxicityRashLeukopenia/AgranulocytosisArthralgias
17. Thyrotoxicosis (Slide 5 of 5)Patient educationHepatotoxicityReport jaundice, dark urine, pale stoolsAgranulocytosisReport malaise, fever, oropharyngeal infectionContinue 12-24 months to induce remissionPotential need for lifelong treatment with T4