Thyroid Disorders

PHCL 442

Thyroid Disorders

PHCL 442

Hadeel Al-Kofide MS.c

Topics to be coveredTopics to be covered

• Thyroid physiology

• Hypothyroidism

• Hyperthyroidism

Thyroid PhysiologyThyroid Physiology

HypothyroidismHypothyroidism

• Causes

• Clinical presentation

• Goals of therapy

• Treatment options

• Monitoring

• Special considerations

CausesCauses

• Primary:

Autoimmunue disease: Genetic, more common in female

Iatrogenic destruction of thyroid: Example: in surgey

Drug induced: example: Iodine & lithium

• Secondary:

Due to deficiency in TSH or TRH

Hypothyroidism

Clinical PresentationClinical Presentation

• Increase weight

• Loss of appetite

• Cold intolerance

• Headache

• Muscle cramps & pain

• Weakness, tiredness & fatigue

• Dyspnea

• Constipation

Hypothyroidism

Symptoms

Clinical PresentationClinical Presentation

• Thin brittle nails

• Puffiness of face & eyelid

• Yellowish skin

• Thinning of outer eyebrow

• Peripheral edema

• Bradycardia

• Hypertension

Hypothyroidism

Physical Findings

Clinical PresentationClinical Presentation

• High TSH

• Low T3 & T4

• Positive antibodies

• Anemia (decrease Hct & Hgb)

Hypothyroidism

Laboratory

Goal of TherapyGoal of Therapy

• Normalize thyroxin level

• Provide symptomatic relief

• In a child, or infant we want to maintain normal growth &

development

Hypothyroidism

TreatmentTreatment

1) Natural thyroid products: Desiccated thyroid (T3 & T4)

• Problems with these preparations is that they can cause severe

allergy

• There is no bioequivalence: different content from batch to

batch

• It losses its potency by time

Hypothyroidism

NO more used

TreatmentTreatment

2) Triiodothyroxine (T3)

• Not recommended for routine use due to:

Short acting given 4 times a day

Because this drug contains the active form T3 this can cause

fast supra-physiological levels then soon go back to normal &

so on (fluctuation)

This is considered a major problem specially in elderly

patients & patients with cardiac problems

Hypothyroidism

TreatmentTreatment

2) Triiodothyroxine (T3)

• Used only in the following situations:

Myxedema coma

Patients with impaired conversion from T4 to T3

Hypothyroidism

TreatmentTreatment

3) Liotrix (T3 & T4)

• Combination of T4 & T3 (4:1)

• It has same disadvantages of any preparation containg T3

• Expensive

• Not commonly used

Hypothyroidism

TreatmentTreatment

4) Levothyroxine

• Drug of choice in hypothyroidism

• Advantages:

Stability & uniform potency

Low cost

No allergy

Long half life (7 days so can give once daily)

Hypothyroidism

TreatmentTreatment

4) Levothyroxine

• Due to problems in drug absorption we advice patients to take it

on empty stomach (at least 60 minutes before meals)

• Cholestyramine, sucralfate, aluminum containing antacid can

decrease absorption so must space between them

• Also it is affected by enzyme inducers & inhibitors (ex:

rifampicin)

• Dose: 1.6 – 1.7 mcg/kg/day

Hypothyroidism

MonitoringMonitoring

• Improvement in symptoms

• Improvement in lab findings

• Improvement will start in 2-3 weeks but maximum effect after

4 -6 weeks

• Monitor patients for TSH, T3 & T4 every 6-8 weeks

Hypothyroidism

Special ConsiderationsSpecial Considerations

Pregnancy:

• Usually pregnant women require larger doses of thyroxine,

around 20-50% increase in dose

• After delivery can go back to usual dose

Hypothyroidism

Special ConsiderationsSpecial Considerations

Subclinical hypothyroidism:

• Normal T3 & T4 but high TSH

• Only mild symptoms

• Look at each patient individually then it depends if you will treat

him or not

• Patients with TSH more than 10 mIU/L must be given thyroxine

even in the absence of symptoms

Hypothyroidism

Special ConsiderationsSpecial Considerations

Myxedema coma:

• The end stage of long standing uncorrected hypothyroidism

• It can lead to coma, hypoxia & psychosis

• Mortality from 60-70%

• Treatment of choice: could use products with T3 (fast action)

but better is IV L-thyroxine 400-500 mcg

Hypothyroidism

HyperthyroidismHyperthyroidism

• Causes

• Clinical presentation

• Goals of therapy

• Treatment options

• Monitoring

• Special considerations

CausesCauses

1) Graves’ disease:

• Autoimmune disease: the presence of antibodies affecting

TSH

• All gland is hyperactive producing large amounts of thyroid

hormone

• Ocular symptoms common in graves’ disease

Hyperthyroidism

CausesCauses

2) Other causes:

• Tumors: could be benign or malignant

• Thyroditis: inflammation (may be due to viruses)

• Drug induced: exogenous thyroid hormone replacement

Hyperthyroidism

Clinical PresentationClinical Presentation

• Heat intolerance

• Weight loss with increased appetite

• Palpitation

• Nervousness

• Tachycardia

• Hypertension (but here due to increase sympathetic tone)

Hyperthyroidism

Symptoms

Clinical PresentationClinical Presentation

• Diarrhae (due to increased GI activity)

• Tremor

• Weakness

• Fatigue

• Amenorrhea in female

Hyperthyroidism

Symptoms

Clinical PresentationClinical Presentation

• Exophthalmos: lid lag, lid retraction, chemosis, conjunctivitis,

periorbital edema, & loss of extraorbital movement

• Thinning of hair

• Moist skin

Hyperthyroidism

Physical Findings

Clinical PresentationClinical Presentation

• Increase T3 & T4

• Increased Free T3 & T4

• Low TSH

• Thyroid receptor antibodies (TPO antibodies)

• Increase liver enzymes

• Radioactive iodine uptake, how?

Hyperthyroidism

Laboratory

Goals of TherapyGoals of Therapy

• Decrease amount of thyroid hormone

• Improve symptoms of the disease

Hyperthyroidism

Treatment ModalitiesTreatment Modalities

• Surgery

• Drugs

• Radioactive iodine

Hyperthyroidism

SurgerySurgery

Treatment of choice in:

1. Suspected malignancy

2. Patients with goiter with difficulty of breathing

3. Contraindications to other modalities (ex: pregnancy)

4. Failure to respond to medications

Hyperthyroidism

SurgerySurgery

• Subtotal thyroidectomy: avoid risk of hypothyroidism, but

risk of recurrent hyperthyroidism

• If hyperthyroidism occurred after surgery, do not do it again

but use other treatment modalities

Hyperthyroidism

SurgerySurgery

• Advantages: Quick & no lag time

• Disadvantages: expensive, complications

• Before surgery must be in euthyroid state, because with

surgical manipulation there may be release of high amount of

thyroid hormones leading to severe hyperthyroidism (thyroid

storm)

Hyperthyroidism

Drugs used in HyperthyroidismDrugs used in Hyperthyroidism

Thioamides:

1. Propylthiouracil

2. Methimazole

• Mechanism of actions:

They inhibit thyroid hormone synthesis

They also suppress autoantibody synthesis

Hyperthyroidism

Drugs used in HyperthyroidismDrugs used in Hyperthyroidism

Thioamides:

• Methimazole: drug of choice because only one tablet is

requires, less expensive & no bitter taste

• Propylthiouracil: needs 7 tablets 2-3 times/day, but it is safer

in pregnant & lactation; have the advantage of inhibiting

converting T4 to T3 so decreasing the active form & this is

an advantage for patients with thyroid storm

Hyperthyroidism

Drugs used in HyperthyroidismDrugs used in Hyperthyroidism

Thioamides:

• Monitoring therapy:

1. Baseline FT4 & TSH before treatment then measure every 4-6

weeks, then when normal every 3 months, if normal for 2 times

then measure yearly

2. They can cause agranulocytosis: make baseline WBC &

differentials before treatment & during therapy

3. Liver function test

Hyperthyroidism

Drugs used in HyperthyroidismDrugs used in Hyperthyroidism

Thioamides:

• Duration of therapy: 1- 2 years but patients may need it for

life, so duration of treatment depends on individual patient

Hyperthyroidism

Drugs used in HyperthyroidismDrugs used in Hyperthyroidism

Thioamides:

• Side effects:

1. Rash: if mild continue therapy but give antihistamine or

topical steroids. If more severe rash change to other

thioamide (cross allergy is uncommon)

Hyperthyroidism

Drugs used in HyperthyroidismDrugs used in Hyperthyroidism

Thioamides:

• Side effects:

2. Hepatitis: Increase in liver function test, with propylthiouracil

it is not dose related but with methimazole doses more than 40

mg increase risk of hepatitis. If liver functioned increased early

in therapy then went to normal can continue on same treatment

but if kept increasing then must DC the drug

Hyperthyroidism

Drugs used in HyperthyroidismDrugs used in Hyperthyroidism

Thioamides:

• Side effects:

3. Agranulocytosis: decrease in neutophils, usually develops

within the first 3 months of treatment. Tell the patient to

watch for symptoms such as: unexplained fever, blue like

symptoms & sore throat

Hyperthyroidism

Radioactive IodineRadioactive Iodine

• The only organ which traps iodine (advantage)

• This radioactive iodine causes death of cells

• Minimum side effects because don’t go to other sites in the

body

• Before treatment patient must be in euthyroid state (use

drugs)

Hyperthyroidism

Radioactive IodineRadioactive Iodine

Treatment of choice in:

• Patients failed other treatment modalities

• Debilitated patient (or patients with poor surgical candidates)

• Recurrent hyperthyroidism after surgery

Contraindication:

• Pregnancy

Hyperthyroidism

Radioactive IodineRadioactive Iodine

Advantages:

• Safe, effective treatment, painless & economic

Disadvantage:

1. Takes long time 10-12 months for total affect to appear

2. Patients fear from radiation

3. Patients will have hypothyroidism

Hyperthyroidism

Radioactive IodineRadioactive Iodine

Advantages:

• Safe, effective treatment, painless & economic

Disadvantage:

1. Takes long time 10-12 months for total affect to appear

2. Patients fear from radiation

3. Patients will have hypothyroidism

Hyperthyroidism

Beta-BlockersBeta-Blockers

• Because increase sympathetic activity, beta-blockers may help in

reducing symptoms

• Propranolol have the advantage of inhibiting the conversion of T4

to T3 (useful in thyroid storm)

Advantages:

1. Used as adjunct to surgery & radioactive iodine to control

symptoms

2. In pregnant women until she delivers to control symptoms

Hyperthyroidism

Iodinated Contrast MediaIodinated Contrast Media

• Effective short term treatment

• They have the advantage of inhibiting the conversion of T4 to

T3

• Used in: Pre-surgery& after radioactive iodine (not before)

• Not used in: pregnancy

• Must give with it thioamides (need around 8 weeks to work)

Hyperthyroidism

Monitoring Therapy in HyperthyroidismMonitoring Therapy in Hyperthyroidism

• T3, T4 & TSH: every 4-6 weeks then every months then

yearly

• Watch signs & symptoms of hypothyroidism (specially after

surgery or radioactive iodine)

Hyperthyroidism

Pregnancy & HyperthyroidismPregnancy & Hyperthyroidism

• Hyperthyroidism can happen during early pregnancy &

symptoms decrease after 2nd or 3rd trimester

• So at this stage patients may not take their medication so after

delivery there will be exacerbation leading to thyroid storm

• Treatment of choice: surgery or thioamides

Hyperthyroidism

Thyroid StormThyroid Storm

• Acute onset of fever, tachycardia, tachypnea, confusion,

psychosis & coma

• Mortality rate can reach 50%

• Needs acute & immediate treatment

• Treatment: Please look at table 49-11 at applied therapeutics

Hyperthyroidism

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