disorders of thyroid function - university of colorado … · disorders of thyroid function michael...
TRANSCRIPT
![Page 1: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/1.jpg)
Disorders of Thyroid Function
Michael T. McDermott MDDirector, Endocrinology and Diabetes Practice
University of Colorado Hospital
![Page 2: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/2.jpg)
Thyroid Hormone Axis
TRH
T3 + T4
Hypothalamus
TSH
![Page 3: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/3.jpg)
Thyroid Function TestingTesting / Screening TSH: 1o Thyroid Disease (99%) TSH + Free T4: 2o Thyroid Disease (1%)
TSH (1o Hypothyroidism) Free T4: Good Accuracy
TSH (1o Hyperthyroidism) Free T4: Good Accuracy Total T3: Good Accuracy Free T3 Assays: Poor Accuracy - Avoid
![Page 4: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/4.jpg)
Case HistoryA 28 year old woman presents with 4 month history of fatigue, nervousness, palpitations and heat intolerance.PE: BP 148/70 P 108 Ht 5’6’’ Wt 115 lb.
Thyroid diffusely enlarged (3 x normal)Lab: TSH: < 0.03 mU/L (nl: 0.5-5.0)
Free T4 7.8 ng/dl (nl: 0.7-2.7)Total T3 698 ng/dl (nl: 90-190)
RAIU: 4 hr. = 62% 24 hr. = 74%Thyroid Scan: Homogeneous Uptake
![Page 5: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/5.jpg)
Hyperthyroidism
TRH
T3 + T4
Hypothalamus
TSH
TSH Free T4 Total T3
TSHnl Free T4nl Total T3
OvertHyperthyroidism
SubclinicalHyperthyroidism
![Page 6: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/6.jpg)
ThyrotoxicosisDifferential Diagnosis - RAIU
Graves’ Disease
Toxic MNG
Toxic Nodule
HCG Secreting Tumor
Central Thyrotoxicosis
Postpartum Thyroiditis
Silent Thyroiditis
Subacute Thyroiditis
Factitious Thyrotoxicosis
Iodine Induced
Amiodarone Induced
High RAIU Low RAIU
![Page 7: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/7.jpg)
Graves’ Disease
Toxic MNG
Toxic Nodule
HCG Secreting Tumor
Central Thyrotoxicosis
High RAIU
Order Thyroid Scan
ThyrotoxicosisDifferential Diagnosis - RAIU
![Page 8: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/8.jpg)
Graves’ DiseaseDiffuse Uptake
TSH Receptor Antibodies Stimulate Iodine Uptake and Thyroid Hormone Production
![Page 9: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/9.jpg)
Toxic Multinodular GoiterPatchy Uptake
Mutation of TSH Receptor or SubunitCausing Autonomous Nodule Function
![Page 10: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/10.jpg)
Toxic Thyroid NoduleSolitary Uptake
Mutation of TSH Receptor or SubunitCausing Autonomous Nodule Function
![Page 11: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/11.jpg)
ThyrotoxicosisDifferential Diagnosis - RAIU
Postpartum Thyroiditis
Silent Thyroiditis
Subacute Thyroiditis
Factitious Thyrotoxicosis
Iodine Induced
Amiodarone Induced
Low RAIU
No Thyroid Scan Needed
DestructiveThyroiditis
![Page 12: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/12.jpg)
Destructive ThyroiditisLow RAIU
Postpartum ThyroiditisLymphocytic Thyroiditis
Silent ThyroiditisLymphocytic Thyroiditis
Subacute ThyroiditisGranulomatous ThyroiditisPain and TendernessElevated ESR
Destruction ofThyroid FolliclesWith Release ofT4 and T3 into
Circulation
![Page 13: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/13.jpg)
Destructive ThyroiditisClinical Course
0
1
2
3
4
5
6
7
8
0 1 2 3 4 5 6 7 8 9
Free T4TSH
Months
Units
*20-25% Remain Hypothyroid
*
Free T4
TSH
Postpartum, Silent, and Subacute Thyroiditis
![Page 14: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/14.jpg)
Graves’ DiseaseTreatment
Anti-Thyroid Drugs for 12-18 Months Methimazole: 30 mg QD; in 1-2 months Propylthiouracil: 100 mg TID; in 1-2 months Beta Blocker: Atenolol 50 mg QD until euthyroid Goal: Rapid Symptom Relief; Remission: ~ 20-40% Liver Disease: PTU (AST, ALT, Liver Failure) Agranulocytosis: ~1/200 (Check CBC when Febrile)
Radioiodine (I-131) Therapy Hypothyroidism occurs in ~ 80-100% (Avg: 3 Months)
Surgical Therapy Hypothyroidism occurs in ~ 80-100% (1-2 Weeks)
![Page 15: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/15.jpg)
Toxic MNG and Toxic NoduleTreatment
Anti-Thyroid Drugs for 4-6 Weeks (prior to other Rx) Methimazole: 30 mg QD; in 1-2 months Propylthiouracil: 100 mg TID; in 1-2 months Beta Blocker: Atenolol 50 mg QD until euthyroid Goal: Rapid Symptom Relief; Remission will not Occur Liver Disease: PTU (AST, ALT, Liver Failure) Agranulocytosis: ~1/200 (Check CBC when Febrile)
Radioiodine (I-131) Therapy Hypothyroidism occurs in ~ 50% (Avg: 3-12 Months)
Surgical Therapy Hypothyroidism occurs in ~ 50% (1-2 Weeks)
![Page 16: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/16.jpg)
Destructive ThyroiditisTreatment
Thyrotoxic PhaseBeta Blockers: if needed for symptomsAnti-Thyroid Drugs: not effective
Hypothyroid PhaseLevothyroxine: if needed for symptoms
Resolution75-80% return to Normal20-25% remain Hypothyroid
Postpartum, Silent, and Subacute Thyroiditis
![Page 17: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/17.jpg)
Case PresentationA 62 y.o. woman experiences occasional palpitations, fatigue and forgetfulness.PMH: HTN, DJD, GERDMeds: lisinopril, tylenol prnPE: Ht 5’8’’ 180 lb. BP 145/80 P 84
Thyroid: nodular goiterLab: TSH < .01 mU/L
Free T4 1.8 ng/dl (nl, 0.7-2.7) Total T3 165 ng/dl (nl, 90-190)
RAIU: 26% (24 hr.) Scan: patchy uptake
![Page 18: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/18.jpg)
Subclinical HyperthyroidismSmall Increase in Free T4 = Large Decrease in TSH
0.7 ng/dl
2.7 ng/dl 5.0 mU/L
0.5 mU/L
Free T4 TSHNormal Range Change Normal Range Change
![Page 19: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/19.jpg)
Subclinical HyperthyroidismClinical Concerns
Symptoms
Osteoporosis
Atrial Fibrillation
![Page 20: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/20.jpg)
2007 subjects > 60 yo (1193 women, 814 men) TSH measured; 10 year follow-up
RelativeRisk
4
2
0
3.1*
< 0.1
Subclinical Hyperthyroidism Risk of Atrial Fibrillation
Sawin CT, NEJM 331: 1249, 1994
0.1-0.4TSH mU/L 0.4-5.0 > 5.0
1.6 1.0 1.4
![Page 21: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/21.jpg)
Surks M, JAMA 2004; 291:228-38Col N, JAMA 2004; 291:239-43
Subclinical HyperthyroidismTreatment – Consensus Recommendations
Not routinely recommended without symptoms
On LT4 Rx: dose until TSH in normal range
If RAIU: consider ATD or I-131 Rx
On LT4 Rx: dose until TSH in normal range
TSH 0.1-0.45 mU/L
TSH < 0.1 mU/L
![Page 22: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/22.jpg)
Case HistoryA 33 year old woman presents for evaluation of fatigue and weight gain of 15 lb. PMH: DM type 1Meds: insulinPE: BP 134/80 P 64 Ht 5’6’’ Wt 154 lb.
moderate goiter, periorbital edema, delayed reflex relaxation
Lab: TSH 112 mU/L (nl: 0.5-5.0)TPO antibodies 72.5 units (nl: < 0.3)
![Page 23: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/23.jpg)
Hypothyroidism
TRH
Hypothalamus
TSH
T3 + T4
TSH Free T4
TSHnl Free T4
OvertHypothyroidism
SubclinicalHypothyroidism
![Page 24: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/24.jpg)
Primary HypothyroidismEtiology
Lymphocytic Thyroiditis
Thyroidectomy
I-131 Ablation
Medications Lithium
Amiodarone
Alpha Interferon
![Page 25: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/25.jpg)
HypothyroidismTreatment
LT4 1.6 ug/kg: daily starting dose
Recheck TSH: 6 weeks
Titrate LT4 Until: 0.5 < TSH < 2.0 mU/L
Age < 60 Years and No CAD
![Page 26: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/26.jpg)
TSH Distribution in Normal Population
TSH Goal (on LT4 Rx): 0.5-2.0 mU/L
![Page 27: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/27.jpg)
LT4 12.5-25 ug: daily starting dose
Recheck TSH: 6 weeks
Titrate LT4 Until: 1.0 < TSH < 3.0 mU/L
HypothyroidismTreatment
Age > 60 Years or CAD
![Page 28: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/28.jpg)
Case HistoryA 68 year old woman with progressive fatigue, mild depression and poor memory.PMH: DJD, GERD Meds: tylenolPE: BP 150/86 P 80 Ht 5’9” Wt 162 lb.
Complete exam normalLab: TSH 10.2 mU/L (nl: 0.5-5.0)
Free T4 0.9 ng/dl (nl: 0.7-2.7)Chol 255 TG 165 HDL 45 LDL 177
Should she be treated for hypothyroidism?
![Page 29: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/29.jpg)
Subclinical HypothyroidismSmall Decrease in Free T4 = Large Increase in TSH
0.7 ng/dl
2.7 ng/dl
Free T4Normal Range Change
5.0 mU/L
0.5 mU/L
TSHNormal Range Change
![Page 30: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/30.jpg)
Mild Thyroid Failure Prevalence - Women
25%
20%
15%
10%
5%
0%
Whickham (n=2,779)Colorado (n=25,862)
Age ~ 30 yr. ~ 50 yr. ~ 80 yr.
Tunbridge W, Clin Endo 7:481, 1977 Canaris G, Arch Intern Med 160:526, 2000 Hollowell J, J Clin Endo Metab 87: 489, 2002
NHANES (n=17,353)
![Page 31: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/31.jpg)
Subclinical HypothyroidismIssues
Symptoms
Lipid Elevation
CVD Risk Factor
![Page 32: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/32.jpg)
HypothyroidismCholesterol Elevation
Canaris G, Arch Intern Med 2000; 160:526
260
240
220
200
Serum TotalCholesterol
(mg/dl)
Euthyroid Mild ThyroidFailure
Hypothyroid
ColoradoStudy
![Page 33: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/33.jpg)
Mild Thyroid FailureLipid Changes with LT4 Therapy
0
5
10
TotalCholesterol
LDLCholesterol
Meta-Analysis: 13 Studies 247 patientsMean TSH 4.8-19.0 mU/L
Danese M, J Clin Endo Metab 85:2993, 2000
CholesterolReduction(mg/dl)
-7.9 mg/dl
-10.3 mg/dl
![Page 34: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/34.jpg)
Subclinical HypothyroidismTreatment – Consensus Conference
LT4 Rx not routinely recommended without symptoms
Clinical Judgment Advised
Recommended: All Pregnant Women
Surks M, JAMA 2004; 291:228-38Col N, JAMA 2004; 291:239-43
Routine LT4 Rx: Reasonable
Clinical Judgment Advised
Recommended: All Pregnant Women
TSH 4.5-10 mU/L
TSH > 10 mU/L
![Page 35: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/35.jpg)
LT4 Rx: 25 ug daily starting dose
Recheck TSH: 6-8 weeks
Adjust LT4 dose: as needed to maintain
Serum TSH: 0.5-2.0 mU/L
Subclinical HypothyroidismTreatment
![Page 36: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/36.jpg)
Case HistoryA 32 year old woman was diagnosed with hypothyroidism 6 months ago. Despite treatment she still complains of fatigue, mild depression and difficulty losing weight. She requests T3 therapy.PMH: hypothyroidism Meds: LT4 125 ug/dPE: BP 122/84 P 80 Ht 5’6” Wt 172 lb.
Complete exam normalLab: TSH 1.2 mU/L (nl: 0.5-5.0)
Free T4 1.3 ng/dl (nl: 0.7-2.7)Total T3 104 ng/dl (nl: 90-190)Should she be treated with LT3?
![Page 37: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/37.jpg)
Persistent Symptoms on LT4 RxCommunity Based Questionnaire Study:
397 Hypothyroid Patients with normal TSH on LT4397 Control Subjects (matched for gender and age)
Saravanan P, Clin Endo 2002; 57:577-85
50%
25%
0%
AbnormalSurveyScore
GeneralHealth
Questionnaire
ThyroidSymptom
Questionnaire
ControlsPatients
26%
34% 35%
49%P = .014 P < .001
![Page 38: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/38.jpg)
Thyroid Hormone Production
T36 ug/d
T320 ug/d
T4101 ug/d
T326 ug/d
20% Secreted80% Converted
from T4Pilo A, Am J Physiol 1990; 258:E715-26
![Page 39: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/39.jpg)
The T3 Hypothesis
T320 ug/d
T4101 ug/d
T320 ug/d100% Converted
from T4
No T4 No T3
“Tissue T3 Deficiency”
![Page 40: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/40.jpg)
Objective Subjective T4/T3Study Benefit Benefit PreferenceBunevicious 1999 No Yes YesWalsh 2003 No No NoSawka 2003 No No NAClyde 2003 No No NASiegmund 2004 No No NASaravanan 2005 No No NAEscobar-Morreale 2005 No No YesApelhof 2005 No No YesRodriguez 2005 No No NALevitt 2005 No No NA Regalbuto 2007 No No NoSlawik 2007 (Central) No No NAEscobar-Morreale 2005 Review: No benefit of T4/T3Grozinsky-Glasberg 2006 Meta-Analysis: No benefit of T4/T3
Combined LT4 / LT3 TherapyRandomized Controlled Trials
![Page 41: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/41.jpg)
Thyroid Hormone Production
T36 ug/d
T320 ug/d
T4101 ug/d
T326 ug/d
20% Secreted80% Converted
from T4
Secretion RatioT4:T3 = 14:1
Pilo A, Am J Physiol 1990; 258:E715-26
![Page 42: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/42.jpg)
Dose LT4 + LT3 T4:T3*
1/4 grains 9.5 + 2.25 2.8:11/2 grains 19 + 4.50 2.8:11.0 grains 38 + 9.0 2.8:11.5 grains 57 + 13.5 2.8:12.0 grains 76 + 18.0 2.8:13.0 grains 114 + 27.0 2.8:1
Normal 100 + 6 14:1*Assumes 80% absorption LT4 and 100% absorption LT3
Armour Thyroid
![Page 43: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/43.jpg)
LT4/LT3 Therapy for HypothyroidismRecommendations
Should all hypothyroid patients be treated with combination LT4/LT3 therapy? No
Should any hypothyroid patients be treated with combination LT4/LT3 therapy? Reasonable if symptoms persist on optimal LT4 Rx
The optimal T4:T3 ratio is ~ 10-14:1.
When using combination LT4/LT3 therapy, measure thyroid tests before meds are taken.
LT3 is best taken BID or as Slow Release
![Page 44: Disorders of Thyroid Function - University of Colorado … · Disorders of Thyroid Function Michael T. McDermott MD Director, Endocrinology and Diabetes Practice University of Colorado](https://reader034.vdocuments.site/reader034/viewer/2022051508/5ace47b77f8b9a1d328ba44d/html5/thumbnails/44.jpg)
Thank You