Hypothyroidism

Thyroid Gland, parathyroid gland

1Knowledge is essentialApplied, it is WisdomWisdom is Happiness

Thyroid Gland

Int.Dr : WAEL ALHALABI

The thyroid gland is a butterfly-shaped organ located in the base of your neck. It releases hormones that control metabolismthe way your body uses energy. The thyroid's hormones regulate vital body functions, including:BreathingHeart rateCentral and peripheral nervous systemsBody weightMuscle strengthMenstrual cyclesBody temperatureCholesterol levels

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Where to look for Thyroid ?

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How the Thyroid Gland WorksThe thyroid is part of the endocrine system, which is made up of glands that produce, store, and release hormones into the bloodstream so the hormones can reach the body's cells. The thyroid gland uses iodine from the foods you eat to make two main hormones:Triiodothyronine (T3)Thyroxine (T4)

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hormonogenesisThyroid Gland6

Thyroid Regulation7

PLASMA T4 + FT4

HYPOTHALAMUS - TRHANT. PITUITARY - TSHTHYROID T4 and T3PLASMA T3 + FT3TISSUES FT4 to FT3, rT3

TSH -R

8The ThyroxinesTri Iodo Thyronine T3 - 10% is from thyroid gland- 90% derived from conversion of T4 to T3Tetra Iodo Thyronine T4- Is exclusively from thyroid glandFrom the thyroid gland- 80% of hormone secreted is T4- 20% of hormone secreted is T3

Half-life of thyroid hormonesHalf-life of thyroid hormones

T4 7daysT3 6hourTSH Males 8 : 1PresentationOften unsuspected and grossly under diagnosed90 % of the cases are Primary HypothyroidismMenstrual irregularities, miscarriages, growth retard.Vague pains, anaemia, lethargy, gain in weight Hair loss, Constipation, Memory loss, Dry, rough pale skinLow free T4 and High TSH14

Suspect HypothyroidismAmenorrheaOligomenorrheaMenorrhogiaGalactorrheaPremature ovarian failureInfertilityDecreased libidoPrecocious / delayed pubertyChronic urticaria15

Classification16

Classification of HypothyroidismA. Primary1. Enlarged Thyroid- Hashimotos (65%)- Iodine Deficiency (25%)- Drug-induced (Lithium)- Dysharmonogenesis2. Normal Thyroid- Spontaneous AtrophicPrimary contd..3. Post Ablative- Permanent- Transient- Sub-clinical4. CongenitalB. Secondary / CentralPituitary/ hypothalamic17

How to interpret results ?18

The Nine Square Game19 To evaluate our Thyroid patient

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LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSH LOW NORMAL HIGHFREE THYROXINE or FT4BASIC THYROID EVALUATION

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LOW NORMAL HIGHFREE THYROXINE or FT4

EUTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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PRIMARYHYPOTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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PRIMARYHYPERTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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LOW NORMAL HIGHFREE THYROXINE or FT4SECONDARYHYPOTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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LOW NORMAL HIGHFREE THYROXINE or FT4SECONDARYHYPERTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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LOW NORMAL HIGHFREE THYROXINE or FT4SUB-CLINICALHYPERTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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LOW NORMAL HIGHFREE THYROXINE or FT4SUB-CLINICALHYPOTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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LOW NORMAL HIGHFREE THYROXINE or FT4NON THYROIDILLNESS or NTI LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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LOW NORMAL HIGHFREE THYROXINE or FT4NTI or Pt.on ELTROXIN LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

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EUTHYROIDSUB-CLINICALHYPERTHYROIDNON THYROIDILLNESS - NTINTI or Pt.on ELTROXINSUB-CLINICALHYPOTHYROIDSECONDARYHYPERTHYROIDSECONDARYHYPOTHYROIDPRIMARYHYPERTHYROIDPRIMARYHYPOTHYROID LOW NORMAL HIGHTHYROID STIMULATING HORMONE - TSHBASIC THYROID EVALUATION

THYROID HORMONESTESTREFERENCE RANGETSHNormal Range 0.3 - 4.0 mU/LFree T4Normal Range 0.7-2.1 ng/dL

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Thyroid AntibodiesAnti Microsomal (TM ) AntibodiesAnti Thyroglobulin (TG) AntibodiesAnti Thyroxine PerOxidase (TPO) Ab.Anti Thyroxine antibodiesThyroid Stimulating (TSA) Antibodies32High titres TPO Ab in Hashimotos & Reidles thyroiditisAnti thyroxine Ab in peripheral resistance to ThyroxineTSA (TSI) in Graves Hyperthyroidism

Other InvestigationsCPK AST LDH Cholestrol Triglycerides Anemia: Normochromic normocytic/macrocytic / microcytic Increased serum prolactin Hyponatremia

ECG finding in hypothyroidismSinus Bradycardia Low voltage Prolongation of the PR interval Bundle branch blocks Flattening or inversion of the T wave Ventricular premature contractions (VPS) Sustained or non-sustained attacks of ventricular tachycardia (VT) Prolongation of the QT interval

35Algorithm forHypothyroidism

36Algorithm for HypothyroidismMeasure TSHElevated TSHNormal TSHMeasure FT4Considering PituitaryNormalLowNoYesSub-clinical hypoTPO +TPO -T4 replAnnual FUPrimary hypothyroidTPO +TPO -No testsMeasure FT4LowNormalNo testsEvaluate PituitarySick EuthyroidDrugs effectHashimotoOthers

TREATMENT

The goal of hypothyroidism therapy is to replace thyroxine to mimic normal, physiologic levels and alleviate signs, symptoms, and biochemical abnormalities

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Treatment of choice: levothyroxine (synthetic levothyroxine, LT4)Dose of Levothyroxine depends on the degree of Hypothyroidism, Age & General health condition of the patientUsually daily replacement dose is 1.6gm/Kg body weight Start with Low DosePatients under age 60, without cardiac disease can be started on 50 100 g/day. Dose adjusted according to TSH levels

Chemically stableIn elderly patients or those with heart disease, start low and go slow (12.525.0 g/day; then slowly the dose by 25-g increments every month until euthyroid). Other therapies (T3 or T3 and T4 mixtures)no advantages versus levothyroxine

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Factors That May Reduce Levothyroxine EffectivenessMalabsorption SyndromesPostjejunoileal bypass surgeryShort bowel syndromeDrugs That Increase ClearanceRifampinCarbamazepinePhenytoinFactors That Reduced T4 to T3 conversionAmiodaroneSelenium deficiency39

Follow upSerum TSH levels should be measured after 6-8 weeks of therapy and dosages should be adjusted accordingly

Target TSH levels should be between 1-2 mU/l

Once a stable TSH is achieved, it should be estimated every year

41How the patient improves Feels better in 2 3 weeksReduction in weight is the first improvementFacial puffiness then starts coming downSkin changes, hair changes take long time to regressTSH starts showing decrements from the high valuesTSH returns to normal eventually

COMPLICATIONSMyxedema coma: Characterized by weakness, hypothermia, hypoventilation with hypercapnia, hypoglycemia, hyponatremia, water intoxication, shock, and death. Treatment is supportive therapy with rewarming, intubation, and IV LT4. Often precipitated by infection or other forms of stress. Consider glucocorticoids for AI, which can coexist with thyroid disease.Other complications: Anemia (normocytic), CHF, depression, and lipid abnormalities (elevated LDL and TG)42

Myxedema

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Myxedema

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Macroglossia

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Xanthomata

46XanthelasmaTuberous Xanthoma

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Solid Oedema

Xanthomata

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Myxoedema with Carotenemia

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Recovery after L-Thyroxine

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Pituitary Tumor Secondary Hypo

Normal Pituitary Fossa

51Massive Pericardial Effusion in Hypo20.2.98

52Clearing of Pericardial Effusion with Rx.26.7.98

53Reappearance of Pericardial Effusion after treatment is discontinued14.9.99

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Hypothyroidism

Health & Medicine

Transcript of Hypothyroidism