3. Dr. Sharda Jain / Dr Jyoti Agarwal
Life Care Centre has a over 200 ppt on shildeshare.net
For benefit of Medical fraternity.
use it yourself & share among your friends
4. The thyroid gland is
a butterfly-shaped
endocrine gland that
is normally located
in the lower front of
the neck
Thyroid Gland
5. Physiological Function of
Thyroid Hormone
• AFFECT GROWTH
– Increase in thyroid hormones increases the rate of
growth and vice versa
– Promote the growth and development of the brain during
foetal life and infancy
– Stimulate carbohydrate metabolism by increasing
metabolic enzyme synthesis
– Stimulate fat metabolism by mobilising lipids from the fat
tissue, thereby decreasing the fat stores of the body
– Cause increased requirement of vitamins because it
increases many enzymes that have vitamins as an
essential
Guyton H. Textbook of Medical Physiology. 2007: 931-943.
6. Physiological Effects
of Thyroid Hormones
• Basal metabolic rate
• Body weight
• Cardiovascular
system
• Blood flow
• Cardiac output
• Heart rate
• Strength of heart
muscle
• Respiration
• Gastrointestinal
motility
• Central nervous
system
• Function of the
muscles
• Sleep
• Endocrine glands
• Sexual functionGuyton H. Textbook of Medical Physiology. 2007: 931-943.
7. USP of Thyroid Gland
• "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.“
7
8. Laboratory determinations of thyroid function are
useful in distinguishing patients with euthyroidism
(normal thyroid gland function) from those with
hyperthyroidism (increased function) or
hypothyroidism (decreased function)
Thyroid Function Test
10. Elevated TSH
(>4.5 mU/L
hypothyroidism
Low TSH (<4.5 mU/L
hyperthyroidism
Normal range: 0.5 –
4.5mU/L
One of the best thyroid function screening test
TSH : Thyroid – Stimulation
Hormone
13. Patterns of thyroid function tests
during assessment of thyroid function
Source: UpToDate.com.
Serum TSH Serum Free T4 Serum T3 Assessment
Normal hypothalamic-pituitary function
Normal Normal Normal Euthyroid
High Low Normal or low Primary hypothyroidism
High Normal Normal Subclinical hypothyroidism
Low High or normal High Hyperthyroidism
Low Normal Normal Subclinical hyperthyroidism
Abnormal hypothalamic-pituitary function
Normal or high High High TSH-mediated hyperthyroidism
Normal or low* Low or low-normal Low or normal Central hypothyroidism
* In central hypothyroidism, serum TSH may be low, normal or slightly high.
14. Antithyroid peroxidase
antibodies
Used to diagnose suspected
Hashimoto’s thyroiditis in
hypothyroidism
Antithyroglobulin
antibodies
Used to diagnose autoimmune
thyroiditis or Graves’ disease in
hyperthyroidism
Thyroid Antibodies
18. 131I used to detect
functional derangements
of thyroid gland.
About 15 mci
of 131I given
intravenously
After a few hours, the patient is monitored at the
neck region by movable gamma-ray counter, which
will pick up the radiation emitted by thyroid gland
RADIOACTIVE IODINE UPTAKE
19. Normal response
• About 25% uptake
by thyroid within 2
hours
• About 50% uptake
by thyroid within
24 hours
Abnormal response
• Increased uptake
in hyperthyroidism
• Decreased uptake
in hyporthyroidism
RADIOACTIVE IODINE UPTAKE
21. Hypothyroidism
• 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.
21
23. Case Presentation 1
• During her routine visit to
doctor,Dr. Lakshmi Devi , an
apparently healthy 63-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.
Serum TSH
10 mlU/L(0.3-
5.5)
Serum free T4
1.3 ng/dL(0.7-
2)
Serum total cholesterol
205mg/dL
(150-200)
Serum HDL cholesterol
46 mg/dL(30-
60)
Serum LDL cholesterol
150 mg/dl(80-
150)
Thyroperoxidase antibodies Positive
24. • 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 10 mIU/L and
1.4 ng/dL, respectively.
• Diagnosis: Subclinical
hypothyroidism (Hashimoto’s
thyroiditis)
Serum TSH
10 mlU/L(0.3-
5.5)
Serum free T4
1.3 ng/dL(0.7-
2)
Serum total cholesterol
205mg/dL
(150-200)
Serum HDL cholesterol
46 mg/dL(30-
60)
Serum LDL cholesterol
150 mg/dl(80-
150)
Thyroperoxidase antibodies Positive
Case Presentation 1
26. Hypothyroidism
Thyroid gland
• 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
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.
27. SECONDARY HYPOTHYROIDISM
• 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
27
1. Ladenson P. Cecil Medicine. 2008:1698-1713.
28. 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
LadensonP, Kim M. Cecil Medicine. 2008:1698-1713.
29. 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.
31. 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
1. Ladenson P and Kim M. Cecil Medicine. 2008:1698-1713.
2. Jameson JL, et al. Harrison'sPrinciples of Internal Medicine. 2008: 2224-2247.
Symptoms1,2
– Dyspnea
– Hoarseness of voice
– Hearing Impairment
– Carpal tunnel
syndrome
– Menorrhagia(miscarri
age)
– Paresthesia
32. 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
1. Ladenson P and Kim M. Cecil Medicine. 2008:1698-1713.
2. Jameson JL et al. Harrison'sPrinciples of Internal Medicine. 2008: 2224-2247.
33. Clinical Manifestations: Signs
• 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.
34. 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, 2006:1-13
http://www.aace.com/pub/pdf/guidelines/hypo_hyper.pdf.
T3/T4
35. 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
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.
36. • Desiccated thyroid
hormone and T3+T4
mixture: Insufficient
evidence and not
recommended for
replacement therapy by
the AACE guidelines
Treatment Overview
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.
38. Subclinical Hypothyroidism:
Dr. Lakshmi’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 ie.
I in 20 %
• Most common cause: autoimmune
thyroiditis (Hashimoto’s disease)
• Predisposing factors
– Advancing age
– Greater iodine consumption
• Often asymptomatic
• May represent early thyroid failure
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.
Lifecare’s Experience
• Infertility – 16%
• Recurrent Abortion 18%
• Women Population 11%
39. 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
Monitoring
Monitor 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 hormone
2. FT4: Free Thyroxine
3. Mo: Months
Rule out hypopituitarism
40. 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
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.
41. Subclinical Hypothyroidism
• 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.
43. 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.
44. 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.
46. Dr. Lakshmi's Case: Management
• Dr. Lakshmi was put
on LT4 therapy based
on the following
findings:
– Increased TSH
– Positive antithyroid
antibodies
– Dyslipidemia
• Dosage administered
was 50 mcg/day.
• She was asked to visit
again for follow-up
after 8 weeks
48. 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
49. 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
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.
50. 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 T 4 after 4-6 weeks
• Follow up after 6 months and thereafter annually,
once TSH is in normal range
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.
51. Levothyroxine: Dosing
• Adjust doses as appropriate in case of
ABSORPTION VARIABILITY & DRUG
INTERACTIONS
• Keep in mind that inappropriate dose
adjustments can lead to increased costs due
to additional patient visits and laboratory
tests
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.
52. Levothyroxine: Drug Interactions
• Increase LT4 dose with
– Drugs that reduce thyroxine production: lithium,
iodine-containing drugs, and amiodarone
– Drugs that reduce thyroxine absorption: ferrous
sulfate, cholestyramine, 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
http://www.aace.com/pub/pdf/guidelines/hypo_hyper.pdf.
57. Dr. Lakshmi's Case: Therapy and
FOLLOW-UP
– Serum TSH measurement was repeated after 4 , 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.
59. Thyroid dysfunction is quite prevalent in India,
particularly in females
Women and men >35 years of age should be screened
every 5 years
Screening of hypothyroidism is recommended in
women suffering from infertility
The diagnosis of hypothyroidism must be considered
in every patient with depression.
All patients with elevated lipid levels should be
screened for hypothyroidism .
Screening should be done in peri-and post
menopausal women to prevent complications of
hypothyroidism.
Conclusion of HYPOTHYROIDISM in women
60. Diagnosis of hypothyroidism is important in adolescence
because this condition retards Growth in height and
development of secondary sexual
characteristics and delayed onset of puberty
In patients on treatment for both thyroid disorders and
diabetes,
Thyroid status should be kept in mind while titrating
anti - diabetic therapy
Increased TSH values are increasingly noted in the elderly
population.
Screening should be done I peri -and menopausal women
To prevent complications of hypothyroidism
Conclusion
61. • Maternal hypothyroidism should be avoided
by early diagnosis at the first prenatal visit or
At diagnosis of pregnancy to avoid mental
retardation to baby .
• Screening of hypothyroidism is
recommended within first seven days of birth
Conclusion
62. ADDRESS
11 Gagan Vihar, Near
Karkari Morh Flyover,
Delhi - 51
CONTACT US
9650588339
011-22414049
WEBSITE :
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