Hypothyroidism --a clinical perspective

Clinician’s Perspective to Hypothyroidism

Module 2

Copyright © 2011 Abbott India Limited. All rights reserved

"The thyroid gland regulates the metabolic functions of the body in virtually every cell,“ . "Everything from the brain to the skin is affected by the hormone made by the thyroid gland.“

Hypothyroidism "It slows you down,It makes you lethargic and fatigued Your hair becomes brittle, and your skin becomes dry. You become cold much easier than the average person.

2

Case Presentation 1

During her routine visit to doctor, Ayesha, an apparently healthy 70-year-old woman complained of mild fatigue, dry skin, and difficulty in losing weight since last 2 years.

The past medical and surgical history were uneventful.

There was no reported family history of DM/HTN/IHD.

Physical examination results were normal including a non- palpable thyroid gland.

ECG was normal. Fasting and postprandial blood sugar and CBC were within normal limits.

Serum TSH and FT4 tests were repeated 2 weeks after the first visit and were found to be 8.1 mIU/L and 1.4 ng/dL, respectively.

Diagnosis: Subclinical hypothyroidism (Hashimoto’s thyroiditis)

Serum TSH 8.0 mlU/L(0.3-5.5)

Serum free T4 1.3 ng/dL(0.7-2)

Serum total cholesterol220 mg/dL(150-200)

Serum HDL cholesterol46 mg/dL(30-60)

Serum LDL cholesterol 150 mg/dl(80-150)

Serum triglycerides 80 mg/dL(75-150)

Thyroperoxidase antibodies Positive

Hypothyroidism: Overview, Manifestations and Treatment

Hypothyroidism

Condition where there is a reduced production of thyroid hormone1

Categorized as primary and secondary on the basis of its cause

Primary hypothyroidism occurs due to improper functioning of the thyroid gland May be further classified as overt and subclinical

hypothyroidism2,3

Affects approximately 5% of individuals with elderly women being most commonly affected3

Secondary hypothyroidism occurs due to inadequate stimulation of thyroid gland by thyroid stimulating hormone (TSH)

May be due to congenital or acquired defects in the pituitary or hypothalamus

Rare and occurs in less than 1% of individuals3

Thyroid gland

1. Hypothyroidism, Medline Plus. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000353.htm; 2011:1-7.2. Roberts CGP. Lancet. 2004;363: 793-803.3. Ladenson P. Cecil Medicine. 2008:1698-1713.4. AACE medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism, 2006:1-13

http://www.aace.com/pub/pdf/guidelines/hypo_hyper.pdf.

Primary Hypothyroidism: Etiology

Thyroid dysfunction Autoimmune thyroiditis (Hashimoto’s thyroiditis)

Congenital absence or defect in the thyroid tissue

Thyroid removal by surgery

Radio ablation by radio active iodine or irradiation

Destruction of thyroid tissue caused by infiltrative disorders(amyloidosis,sarcoidosis)

Impaired synthesis of thyroid hormone Iodine deficiency----MOST COMMON CAUSE

Congenital enzymatic defects

Drug-mediated: thionamides, amiodarone, lithium, aminoglutethimide,carbemazole

Ladenson P, Kim M. Cecil Medicine. 2008:1698-1713.

Secondary Hypothyroidism: Etiology

Reduced secretion of TRH or TSH Hypothalamic disorders

– Tumor (lymphoma, germinoma, glioma)

– Infiltrative disorders (sarcoidosis, hemochromatosis, and histiocytosis)

Hypopituitarism

– Mass lesions

– Pituitary surgery

– Pituitary irradiation

– Hemorrhagic apoplexy (Sheehan’s syndrome)

– Lymphocytic hypophysitis

Ladenson P, Kim M. Cecil Medicine. 2008:1698-1713.

Clinical Manifestations: Symptoms

Symptoms1,2

Tiredness/ weakness Weight gain with poor appetite Dry skin Cold sensation Hair loss(diffuse alopecia) Nail growth is retarded Poor concentration/memory loss Constipation Dyspnea Hoarseness of voice Hearing Impairment Carpal tunnel syndrome Menorrhagia(miscarriage) Paresthesia1. Ladenson P and Kim M. Cecil Medicine. 2008:1698-1713.

2. Jameson JL, et al. Harrison's Principles of Internal Medicine. 2008: 2224-2247.

Clinical Manifestations: Signs

Signs1,2

Cold peripheral extremities Dry, coarse and yellow skin Puffiness of face, hands and feet Pre tibial non pitting edema Hair loss and brittle nails Bradycardia/ diastolic hypertension Slow relaxation of tendon reflex (woltmans sign) Serous cavity effusions Normal/enlarged/atrophied thyroid gland

Hypothyroidism in children Delayed growth in children and delayed appearance of permanent teeth Delayed or precocious puberty Pseudohypertrophy of muscles

1. Ladenson P and Kim M. Cecil Medicine. 2008:1698-1713.2. Jameson JL et al. Harrison's Principles of Internal Medicine. 2008: 2224-2247.

Laboratory Diagnosis

TSH assay: Primary test to establish the diagnosis

Additional tests: Estimation of free T3 and T4

Test for thyroid autoantibodies

Thyroid scan/ultrasonography

Serum cholesterol- in hypothyroidism

T3/T4

Subclinical hypothyroidism

Overt hypothyroidism

TSH

TSH

AACE medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism, 2006:1-13http://www.aace.com/pub/pdf/guidelines/hypo_hyper.pdf.

T3/T4

Treatment Overview

Goal: To mimic normal, physiological levels and alleviate signs, symptoms, and biochemical abnormalities

Treatment should be tailored to individual needs

Treatment of choice:Levothyroxine (LT4) replacement therapy

Desiccated thyroid hormone and T3+T4

mixture: Insufficient evidence and not recommended for replacement therapy by the AACE guidelines


Subclinical Hypothyroidism

Subclinical Hypothyroidism: Ayesha’s Case

Criteria defining subclinical hyperthyroidism:

Slightly elevated serum TSH levels

FT4 and T3 levels within the reference range

Affects 1-10% of adults, with greater prevalence in women

Most common cause: autoimmune thyroiditis (Hashimoto’s disease)

Predisposing factors

Advancing age

Greater iodine consumption

Often asymptomatic

May represent early thyroid failure


Subclinical Hypothyroidism: Management Algorithm

1. Col NF, et al. JAMA 2004; 291:239-243. 2. Surks MI, et al. JAMA 2004;291:228-238.

Algorithm for the management of subclinical hypothyroidism (T4 = thyroxine: TSH = thyrotropin-stimulating hormone)

Serum TSH >4.5 mU/L

Repeat Serum TSH Measurement with FT4

Measurement 2 to 12 Weeks Later

Serum TSH Level within Reference Range

(0.45 to 4.5 mlU/L)?

Serum TSH Level 4.5 to 10mlU/L

Monitor Every 6 to 12 mo for Several Years

Serum TSH Level > 10mlU/L

Signs or Symptoms Consistent with

Hypothyroidism?

FT4 Level Decreased

(<0.8 ng/dL)?

Treat with Levothyroxine*

Pregnant or Contemplating

Pregnancy?

Consider Levothyroxine Treatment with Periodic

MonitoringMonitor Serum TSH

Every 6 to 12 mo

FT4 Level Decreased

(<0.8 ng/dL)?

Treat with Levothyroxine*

Pregnant or Contemplating

Pregnancy?

Consider Levothyroxine Treatment in Appropriate

Clinical Settings

Yes No Yes No

Yes NoNoYes

Yes No

No Yes

1. TSH: Thyroid stimulating hormone2. FT4: Free Thyroxine3. Mo: Months

Rule out hypopituitarism

Subclinical Hypothyroidism Dosing and Monitoring1,2

Always start with a small dose to prevent risk of Atrial Fibrillation Dose of LT4: 25-50 mcg/day (reduced dose in elderly and in patients with

heart disease) Adjustment in dosage is made in 12.5-25µg inc or dec Serum TSH levels to be measured 6-8 weeks after starting treatment or

after a change in the dosage Target TSH levels: 0.3-3.0 µIU/mL Annual examination after achieving stable TSH levels

Progression to overt hypothyroidism1

Occurs in 3-20% patients Patients with goiter and thyroid antibodies at higher risk for progression

Associated risks1

Progression to overt hypothyroidism Cardiovascular effects Hyperlipidemia Neuropsychiatric effects

1. AACE medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism, 2006:1-13. \http://www.aace.com/pub/pdf/guidelines/hypo_hyper.pdf.2. Shah SN, Joshi SR. Journal of the Association of Physicians of India. 2011;59(Supplement):1-68.

Learning Activity

Learning Activity

All of the following statements related to subclinical hypothyroidism are true, EXCEPT:

A. The most common cause of subclinical hypothyroidism is Hashimoto’s disease.

B. Subclinical hypothyroidism is more common in women.

C. Subclinical hypothyroidism is characterized by elevated levels of TSH and free T4.

D. Subclinical hypothyroidism may represent early thyroid failure.

Case Study

Ayesha's Case: Management

Ayesha was put on LT4 therapy based on the following findings: Increased TSH Positive antithyroid

antibodies Dyslipidemia

Dosage administered was

30 mcg/day. She was asked to visit

again for follow-up after 8 weeks

Levothyroxine

Levothyroxine

Synthetic T4 identical to that produced in the human thyroid gland

Indications: Hypothyroidism: All types Pituitary TSH suppression

– Euthyroid goiters– Thyroid nodules– Subacute or chronic lymphocytic

thyroiditis (Hashimoto’s thyroiditis)

– Adjunct to surgery and radioiodine therapy in the management of thyroid cancer

Synthroid PI,Abbott. 2008

Levothyroxine: Important Facts

Levothyroxine sodium has a narrow therapeutic range

Regardless of indication of use, careful dose titration is necessary to avoid consequences of over- or under- treatment

Even small changes in the dose of LT4 can shift a patient from a euthyroid to a hyperthyroid or hypothyroid state.

The AACE recommends the use of a high-quality brand preparation of levothyroxine

Same brand of LT4 should be received throughout treatment


Levothyroxine: Dosing

Recommended mean daily dose of LT4 therapy: 1.6 mcg/kg of body weight

Initiate with 12.5 mcg daily to a full replacement dose of LT4 depending on age, weight, and cardiac status

Reassess TSH and/or free T4 after 6 weeks Follow up after 6 months and thereafter annually, once

TSH is in normal range Adjust doses as appropriate in case of absorption

variability and drug interactions Keep in mind that inappropriate dose adjustments can

lead to increased costs due to additional patient visits and laboratory tests


Levothyroxine: Drug Interactions

Increase LT4 dose with Drugs that reduce thyroxine production: lithium, iodine-containing

drugs, and amiodarone

Drugs that reduce thyroxine absorption: sucralfate, ferrous sulfate, cholestyramine, colestipol, aluminum-containing antacids, and calcium supplements

Drugs that increase thyroxine metabolism: rifampin, phenobarbital, carbamazepine, warfarin, and oral hypoglycemic agents

Decrease LT4 dose with Drugs that displace thyroxine from binding proteins: furosemide,

mefenamic acid, salicylates, vitamin C

1. Hueston WJ. Treatment of Hypothyroidism. American family physician. 64(10): 1717-1724.2. AACE medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism, 2006:1-13


Learning Activity

Learning Activity

Which of the following agents increase the absorption of LT4?

A. Calcium

B. Furosemide

C. Ferrous sulfate

D. Rifampin

Case Study 1

Ayesha's Case: Therapy and Follow-up

Follow-up

Serum TSH measurement was repeated after 8 weeks of commencing the treatment. They had fallen to 1.2 mIU/mL and remained within the range of 1 to 1.5 mIU/mL on consecutive visits.

She was asked to stay on the treatment and follow up after1 year.

After 1 year of treatment, she had lost weight and was asymptomatic. On investigation, her serum cholesterol and low-density lipoprotein (LDL) cholesterol levels were 190 and 100 mg/dL, respectively.

Case Study 2

Case Presentation: 2

Patient Shobha, a 32-week pregnant 30-year-old woman

presents premature labor Inappropriate weight gain for gestational age Cold intolerance during past few months

Past medical history She was diagnosed with hypothyroidism at the

age of 20 She was on LT4 therapy Last dose modification was 2 years back after which

she continued on same dose.

Case Presentation: 2 (Continued)

Physical Examination Weight : 100 kg Pulse Rate: 68 per minute BP: 140/90 mm Hg Facial puffiness Skin: Cold, Dry Deep tendon reflexes,: Slow relaxation

Thyroid Function Tests Serum TSH: 11 mIU/L Free T4: 1.2 pmol/L

Fetal Examination Fetal distress in labour

Outcome of Pregnancy She delivered a preterm low birth weight male.

Maternal Hypothyroidism

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One of the most common endocrine disorders in pregnancy1

Overt hypothyroidism found in 1.3 per 1000 pregnant women and subclinical hypothyroidism in 23 per 1000 pregnant women1

Most common cause: endemic iodine deficiency2

Women with hypothyroidism carry an increased risk of infertility, miscarriage, and obstetric complications1

Foetal complications: premature birth, low-birth weight (LBW), fetal distress in labor, fetal death, perinatal death, and congenital hypothyroidism1

Even an untreated subclinical hypothyroidism during pregnancy can lead to cognitive impairment in the offspring.3

1. Sahu MT, et al. Arch.Gynaecol. Obstet. 2010;218:215-220.2. Lazaras JH. British Medical Bulletin. 2010;1-12.3. AACE medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism, 2006:1-13


Thyroid Physiology in Pregnancy

Decreased TSHDecreased TSH

PlacentaPlacenta hCGhCG

Increased TH degradation

Increased TH degradation

Thyroid stimulation for increased TH

Production

Thyroid stimulation for increased TH

Production

EstrogenEstrogen

Increased serum TBG

Increased serum TBG

Increased hepatic production of TBGIncreased hepatic production of TBG

Increased half life of TBG

Increased half life of TBG

Type 3 deiodinaseType 3 deiodinase

Stimulates TSH receptorStimulates TSH receptor

Decreased free THDecreased free TH

Stimulation of hypothalamic pituitary axis

Stimulation of hypothalamic pituitary axisIncreased serum THIncreased serum TH

hCG: Human chorionic gonadotropinTSH: Thyroid stimulating hormoneTH: Thyroid hormoneTBG: Thyroxine-binding globulin

Increased oestrogen in pregnancy

Two- to threefold

increase in TBG

Decrease Free T3 and T4

Similar structure of hCG and TSH

hCG stimulates

release of T3 and T4

Transient TSH decrease in

weeks 8 to 14

Increased peripheral

metabolism of T3 and T4

Decrease Free T3 and T4

Thyroid Physiology in Pregnancy

1. Jameson JL. Harrison's Principles of Internal Medicine. 2008:2224-2247.2. Lazarus JH. Br Med Bull.2010;1-12.3. Galofre JC, Davies TF. J Womens Health (Larchmt). 2009;18(11):1847-1856..

0

50

75

100

125

150

0

0.5

1.5

2.5

3.5

4.5

40 8 12 16 20 24 28 32 36 40

TS

H (

mU

/L)

hC

G (

IU/m

L

hCG

TSH

Weeks of gestation

0

1.5

2.0

2.5

3.0

3.5

0

5

10

15

20

25

40 8 12 16 20 24 28 32 36 40

TT

4 (m

cg/d

L)

TB

G (

mg

/dL

)

TBG

Total T4

Weeks of gestation

0.2

0.6

1.0

1.4

1.8

160

220

280

340

400

40 8 12 16 20 24 28 32 36 40

FT

3 (p

g/d

L)

FT

4 (n

g/d

L)

Free T4

Free T3

Weeks of gestation

A

B CTBG: Thyroxine- binding globulinTSH: Thyroid stimulating hormoneHCG: Human chorionic gonadotropinTT4: Total thyroxineFT3: Free triiodothyronineFT4: Free thyroxine

Thyroid Function Tests in Pregnancy

FT4, Free thyroxine; FT3, Free triiodothyronine; TSH, Thyroid stimulating hormone

Referral Values for TFT in Pregnant Indian Women1,2

Thyroid Hormone

Normal Values in Nonpregnant

Trimester Range (5th-95th Percentile)

FT33.7-7.2 pM/L(240.26-467.53

pg/dL)

I 1.92-5.86 pM/L (124.68-380.51 pg/dL)

II 3.2-5.73 pM/L (207.8-372 pg/dL)

III 3.3-5.18 pM/L (214.3-336.36 pg/dL)

FT412-23 pM/L (0.93-1.79

ng/dL)

I 12-19.45 pM/L (0.93-1.51 ng/dL)

II 9.48-19.58 pM/L (0.74-1.521 ng/dL)

III 11.32-17.7 pM/L (0.88-1.38 ng/dL)

TSH 0.27-4.2 µIU/mL

I 0.6-5.0 µIU/mL

II 0.44-5.78 µIU/mL

III 0.74-5.7 µIU/mL

1. Marwaha RK. BJOG. 2008;115(5):602-606.2. SI Units for Clinical Data. University of North Carolina.


AACE recommendations

Carry out TSH assay routinely before pregnancy or during the first trimester to rule out thyroid disorder

Avoid complications by administering thyroid hormone replacement therapy

Both mild as well as overt hypothyroidism are managed by administering levothyroxine therapy which can be safely administered during pregnancy

Assess TSH levels every 6 weeks during pregnancy for appropriate dose adjustments

Increase the dose of thyroid hormone in pregnant women with moderate to severe hypothyroidism



Preconception: Optimize therapy in patients with preexisting disease

Pregnancy confirmed: Increase dose by 30-50% of preconception dose

Target levels

TSH<2.5 mIU/L in the first trimester

TSH<3 mIU/L in later pregnancy

After delivery, reduce dose to preconception dose

Assess thyroid function at 6 weeks postpartum

Post-ablative and post-surgical hypothyroidism require higher dose

Lazaras JH. British Medical Bulletin. 2010;1-12.

Learning Activity

Women with hypothyroidism carry an increased risk of ______.

A. Infertility

B. Miscarriage/spontaneous abortion

C. Maternal hypertension

D. All of the above

Case Presentation II: Congenital Hypothyroidism

The baby delivered by Shobha was apparently normal.

Findings on neonatal examination are within normal limits

Neonatal screening for congenital hypothyroidism on the 3rd day by cord blood

TSH: 38 mIU/L

Serum free T4: 0.5 ng/dL

Diagnosis: Congenital Hypothyroidism

Congenital Hypothyroidism

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Congenital Hypothyroidism

Abnormality in the development of thyroid gland (dysgenesis or agenesis) and defect in the biosynthesis of thyroid hormones

Prevalence rate 1 in 4000 newborn infants in regions of sufficient daily iodine intake

2:1 incidence in females compared with males

Causes: Endemic iodine deficiency, genetic mutation, and hemangiomas

Routine thyroid function screening in neonates is recommended since no apparent clinical manifestation

Untreated congenital hypothyroidism results in development of cretinism

Do not delay diagnosis of congenital hypothyroidism until physical manifestations are seen Mental retardation

Deafness

Short stature

Characteristic facial deformities

Roberts CGP et al. Lancet. 2004;363: 793-803.

Congenital Hypothyroidism: Clinical Features

Roberts CGP et al. Lancet. 2004;363: 793-803.

Infants Children and Adolescents

Hypothermia Growth failure

Poor feeding Markedly delayed bone maturation

Bradycardia Delayed eruption of permanent teeth

Jaundice Muscle pseudohypertrophy

Enlarged posterior fontanel Delayed or precocious puberty

Umbilical hernia Pituitary enlargement

Galactorrhoea

Rastogi and LaFranchi. Orphanet Journal of Rare Diseases 2010,5:17;1-22.

DIAGNOSTIC ALGORITHM

Screen the newborn for hypothyroidism:Initial T4 <10%, TSH ↑

Or Initial TSH ↑Clinical suspicion of hypothyroidism

Measure serum TSH andfree T4 (or T4 and T3 resin uptake)

TSH ↑(>9 mU/L)Free T4 ↓ (<0.6 ng/dL)

Diagnosis primary CH confirmed

TSH ↓ or normal (<9 mU/L)Free T4 ↓ (<0.6 ng/dL)

Diagnosis likely secondary(central) hypothyroidism

Other diagnostic tests todetermine etiology (optional):•Radionuclide uptake and scan•Ultrasonography•Serum thyroglobulin•Maternal antithyroid antibodies•Urinary iodine

• Isolated: TSHβ gene analysis• Evaluate for other pituitary hormone

deficiencies• MRI of brain• Eye exam to check for optic nerve

hypoplasia

Diagnosis Of Congenital Hypothyroidism

TSH: Thyroid stimulating hormoneT4: ThyroxineT3: TriiodothyronineFree T4: Free thyroxineTSHβ: Thyroid stimulating hormone beta

Congenital Hypothyroidism Case: Follow Up

Initial work-up for Shobha’s child

The baby was referred to pediatric endocrinologist

Thyroid ultrasonography showed a normal thyroid gland.

Management

The baby was started on LT4 at an initial daily dose of 50 mcg

The serum T4 normalized in 3 days

TSH normalized by end of 2 weeks

The mother was asked to follow-up with the baby on monthly basis.

Management of Congenital Hypothyroidism

Goal: To normalize T4 within 2 weeks and TSH within 1 month

Assess permanence of congenital hypothyroidism If initial thyroid scan shows ectopic/absent gland, congenital

hypothyroidism is permanent

If initial TSH is <50 mIU/L and there is no increase in TSH after newborn period, off- therapy period is recommended at 3 years of age

If TSH increases during the off-therapy period, consider the condition as permanent congenital hypothyroidism

Medications: LT4: 10-15 g/kg by mouth once-daily

Monitoring: Recheck T4 and TSH At 2-4 weeks after initiation of LT4 treatment

Every 1-2 months in the first 6 months

Every 3-4 months between 6 months and 3 years of age

Every 6-12 months from 3 years of age to end of growth

Rose SR and Brown RS. Pediatrics. 2006;117(6):2290-2303.

Learning Activity

All of the following signs represent congenital hypothyroidism, EXCEPT

A.Tachycardia

B.Jaundice

C.Enlarged posterior fontanel

D.Umbilical hernia

Comorbid Conditions

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Comorbid Conditions

1. AACE medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism, 2006:1-13 http://www.aace.com/pub/pdf/guidelines/hypo_hyper.pdf.

2. Duntas LH, Biondi B. Semin Thromb Hemost. 2011;37(1):27-34.

Comorbid Conditions (Contd.)

Diabetes mellitus Hashimoto’s thyroiditis may be associated with 10% patients of type

1 diabetes mellitus Approximately one-fourth of female patients with type 1 diabetes

mellitus develop postpartum thyroiditis AACE recommendations for patients with diabetes mellitus

Examine for goiter Assess TSH levels regularly especially in the presence of a goiter or

other autoimmune disorders

Infertility Hypothyroidism due to chronic thyroiditis may cause infertility,

miscarriage, and menstrual irregularities Treatment with LT4 replacement therapy restores normal menstrual

cycle and fertility



Depression

In every patient with depression, diagnosis of overt or subclinical hypothyroidism should be considered

Periodic evaluation for thyroid function should be performed in patients receiving lithium therapy

Treatment is with LT4 replacement therapy

LT4 is indicated occasionally in combination with antidepressants in euthyroid patients with depression



Dyslipidemia and cardiovascular sequelae comorbid with overt hypothyroidism Overt hypothyroidism with dyslipidemia is characterized by

Increased levels of total cholesterol Increased LDL cholesterol

Mechanisms for dyslipidemia Impaired production of TC and Decreased expression of the LDL receptors

Severe cardiovascular disease and premature atherosclerosis, if untreated, lead to

Pericardial effusion Congestive heart failure Coronary artery disease

Duntas LH, Biondi B. Semin Thromb Hemost. 2011;37(1):27-34


Cardiovascular sequelae comorbid with subclinical hypothyroidismSubclinical hypothyroidism is associated with

– Impaired diastolic function and depressed left ventricular systolic function in middle-aged patients

– Increased risks of atherosclerosis and myocardial infarction

– Mortality in patients less than 65 years of age due to cardiovascular events

– Proatherogenic mechanisms that leads to low-grade inflammation and may suggest CVD

– Hypercoagulable stateLT4 therapy for subclinical hypothyroidism

– Reverses cardiovascular alterations – Reduces cardiovascular risk factors– Improves dyslipidaemia– Minimizes neurobehavioral changes

Duntas LH, Biondi B. Semin Thromb Hemost. 2011;37(1):27-34

The Cycle of Disease

SubclinicalHypothyroidism

Emerging Risk

Factors CVD

Endothelial Dysfunction

Cardiac Alterations

Blood Pressure

Hyperlipidemia

Hemostatic Balance

Obesity

CVD: Cardiovascular disease

Learning Activity

Learning Activity

Which of the following statements are TRUE regarding LT4 therapy in hypothyroidism? (Select all that apply.)

A.Congenital hypothyroidism is treated with LT4 at a dose of 50-100 mcg/kg orally once-daily.

B.LT4 therapy for subclinical hypothyroidism reverses cardiovascular alterations.

C.LT4 is contraindicated in combination with antidepressants in euthyroid patients with depression.

D.Both mild as well as overt hypothyroidism are managed by administering levothyroxine therapy.

Hypothyroidism --a clinical perspective

Education

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