The document discusses the thyroid gland and hypothyroidism. It notes that the thyroid gland regulates vital body functions through hormones like T3 and T4. Hypothyroidism is the most common endocrine disease and is often underdiagnosed. It presents with symptoms like fatigue, weight gain, and menstrual irregularities. Diagnosis involves low free T4 and high TSH levels. Treatment is typically lifelong levothyroxine supplementation to replace thyroid hormones. The goal is to alleviate symptoms and maintain normal TSH levels.

1. 1
Knowledge is essential
Applied, it is Wisdom
Wisdom is Happiness

2. Int.Dr : WAEL ALHALABI

3.  The thyroid gland is a butterfly-shaped organ located in
the base of your neck. It releases hormones that control
metabolism—the way your body uses energy. The thyroid's
hormones regulate vital body functions, including:
 Breathing
 Heart rate
 Central and peripheral nervous systems
 Body weight
 Muscle strength
 Menstrual cycles
 Body temperature
 Cholesterol levels
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4. Where to look for Thyroid ?
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5.  How the Thyroid Gland Works
The 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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6. Thyroid Gland
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7. Thyroid Regulation
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PLASMA T4 + FT4
HYPOTHALAMUS - TRH
ANT. PITUITARY - TSH
THYROID T4 and T3
PLASMA T3 + FT3
TISSUES FT4 to FT3, rT3
TSH -R

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The Thyroxines
Tri Iodo Thyronine – T3
- 10% is from thyroid gland
- 90% derived from conversion of T4 to T3
Tetra Iodo Thyronine – T4
- Is exclusively from thyroid gland
From the thyroid gland
- 80% of hormone secreted is T4
- 20% of hormone secreted is T3

9. Half-life of thyroid hormonesHalf-
life of thyroid hormones
 T4 7days
 T3 6hour
 TSH <1hour
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10. Thyroid Function Tests
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11. Thyroid Function Tests
1. TSH
2. Free T4
3. Free T3
4. Anti-Thyroid Antibodies
5. Nuclear Scintigraphy
6. FNAC of nodule
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12. 12
Current Trends in Dx. and Rx.
HYPOTHYROIDISM

13. General Considerations
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14. Hypothyroidism
Epidemiology
 Most common endocrine disease
 Females > Males – 8 : 1
Presentation
 Often unsuspected and grossly under diagnosed
 90 % of the cases are Primary Hypothyroidism
 Menstrual irregularities, miscarriages, growth retard.
 Vague pains, anaemia, lethargy, gain in weight
 Hair loss, Constipation, Memory loss, Dry, rough
pale skin
 Low free T4 and High TSH
14

15. Suspect Hypothyroidism
1. Amenorrhea
2. Oligomenorrhea
3. Menorrhogia
4. Galactorrhea
5. Premature ovarian failure
6. Infertility
7. Decreased libido
8. Precocious / delayed puberty
9. Chronic urticaria
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16. Classification
16

17. Classification of Hypothyroidism
A. Primary
1. Enlarged Thyroid
- Hashimoto’s (65%)
- Iodine Deficiency (25%)
- Drug-induced (Lithium)
- Dysharmonogenesis
2. Normal Thyroid
- Spontaneous Atrophic
Primary contd..
3. Post Ablative
- Permanent
- Transient
- Sub-clinical
4. Congenital
B. Secondary / Central
Pituitary/ hypothalamic
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18. How to interpret results ?
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19. The Nine Square Game
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To evaluate our Thyroid patient

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LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
FREETHYROXINEorFT4
BASIC THYROID EVALUATION

21. 21
FREETHYROXINEorFT4
EUTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

22. 22
FREETHYROXINEorFT4
PRIMARY
HYPOTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

23. 23
FREETHYROXINEorFT4
PRIMARY
HYPERTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

24. 24
FREETHYROXINEorFT4
SECONDARY
HYPOTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

25. 25
FREETHYROXINEorFT4
SECONDARY
HYPERTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

26. 26
FREETHYROXINEorFT4
SUB-CLINICAL
HYPERTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

27. 27
FREETHYROXINEorFT4
SUB-CLINICAL
HYPOTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

28. 28
FREETHYROXINEorFT4
NON THYROID
ILLNESS or NTI
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

29. 29
FREETHYROXINEorFT4
NTI or Pt.
on ELTROXIN
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

30. 30
FREETHYROXINEorFT4
EUTHYROID
SUB-CLINICAL
HYPERTHYROID
NON THYROID
ILLNESS - NTI
NTI or Pt.
on ELTROXIN
SUB-CLINICAL
HYPOTHYROID
SECONDARY
HYPERTHYROID
SECONDARY
HYPOTHYROID
PRIMARY
HYPERTHYROID
PRIMARY
HYPOTHYROID
LOW NORMAL HIGH
THYROID STIMULATING HORMONE - TSH
BASIC THYROID EVALUATION

31. THYROID HORMONES
TEST REFERENCE RANGE
TSH Normal Range 0.3 - 4.0 mU/L
Free T4 Normal Range 0.7-2.1 ng/dL
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32. Thyroid Antibodies
 Anti Microsomal (TM ) Antibodies
 Anti Thyroglobulin (TG) Antibodies
 Anti Thyroxine PerOxidase (TPO) Ab.
 Anti Thyroxine antibodies
 Thyroid Stimulating (TSA) Antibodies
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 High titres TPO Ab in Hashimotos & Reidle’s thyroiditis
 Anti thyroxine Ab in peripheral resistance to Thyroxine
 TSA (TSI) in Graves’ Hyperthyroidism

33. Other Investigations
 CPK
 AST
 LDH
 Cholestrol
 Triglycerides
 Anemia: Normochromic normocytic/macrocytic /
microcytic
 Increased serum prolactin
 Hyponatremia

34. ECG finding in hypothyroidism
 Sinus 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

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36. 36
Algorithm for Hypothyroidism
Measure TSH
Elevated TSH Normal TSH
Measure FT4 Considering Pituitary
Normal Low No Yes
Sub-clinical hypo
TPO + TPO -
T4 repl Annual FU
Primary hypothyroid
TPO + TPO -
No tests Measure FT4
Low Normal
No tests
Evaluate Pituitary
Sick Euthyroid
Drugs effect
Hashimoto
Others

37. 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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38.  Treatment of choice:
 levothyroxine (synthetic levothyroxine, LT4)
 Dose of Levothyroxine depends on the degree of Hypothyroidism, Age &
General health condition of the patient
 Usually daily replacement dose is 1.6µgm/Kg body weight
 Start with Low Dose
 Patients under age 60, without cardiac disease can be started on 50 – 100
μg/day. Dose adjusted according to TSH levels
 Chemically stable
 In elderly patients or those with heart disease, start low and go slow (12.5–25.0
μg/day; then slowly ↑ the dose by 25-μg increments every month until
euthyroid).
 Other therapies (T3 or T3 and T4 mixtures)
 no advantages versus levothyroxine
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39. Factors That May Reduce
Levothyroxine Effectiveness
 Malabsorption Syndromes
 Postjejunoileal bypass
surgery
 Short bowel syndrome
 Drugs That Increase Clearance
 Rifampin
 Carbamazepine
 Phenytoin
 Factors That Reduced T4 to T3 conversion
 Amiodarone
 Selenium deficiency
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40. Follow up
 Serum 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

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How the patient improves
 Feels better in 2 – 3 weeks
 Reduction in weight is the first improvement
 Facial puffiness then starts coming down
 Skin changes, hair changes take long time to regress
 TSH starts showing decrements from the high values
 TSH returns to normal eventually

42. COMPLICATIONS
 Myxedema 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)
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43. Myxedema
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44. Myxedema
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45. Macroglossia
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46. Xanthomata
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Xanthelasma
Tuberous Xanthoma

47. 47
Solid Oedema Xanthomata

48. 48
Myxoedema with Carotenemia

49. 49
Recovery after L-Thyroxine

50. 50
Pituitary Tumor – Secondary HypoNormal Pituitary Fossa

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Massive Pericardial Effusion in Hypo
20.2.98

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Clearing of Pericardial Effusion with Rx.
26.7.98

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Reappearance of Pericardial Effusion
after treatment is discontinued
14.9.99

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We need to apply the current knowledge