3. Introduction
Reduced production of thyroid hormone
is the central feature
It is the second most common endocrine
disorder (after diabetes mellitus) is USA
It is more common in females
F:M ratio is approx 10:1
Rates of hypothyroidism increase
dramatically with age
4. Risk Factors
More common in individuals who have a
family history of thyroid disorders
Hypothyroidism and thyroid cancers are
more common in individuals who have
had irradiation of their neck in childhood
However, most cases occur in individuals
with no risk factors
6. Causes
PRIMARY HYPOTHYROIDISM-
Thyroiditis
o Hashimoto’s throiditis (Chronic
lymphocytic)
o De Quervain’s thyroiditis (Subacute
granulomatous)
o Silent/Painless thyroiditis (Subacute
lymphocytic)
o Reidel’s thyroiditis (Subacute fibrocytic)
7. Iatrogenic causes
o Radioactive iodine treatment of Grave’s ds
o Thyroidectomy
SECONDARY HYPOTHYROIDISM-
Pituitary surgery
Intracranial radiation
Congenital panhypopituitarism
Infiltrative diseases like sarcoidosis, amyloidosis,
hemochromatosis
OTHERS-
Drugs like lithium, interferon, amiodarone
Iodine deficiency
8. PRIMARYV/S SECONDARY
HYPOTHYROIDISM
PRIMARY SECONDARY
SKIN Thick and without wrinkles Thin with fine wrinkles
HAIR Coarse Fine
MENSES Menorrhagia Amenorrhea
SECONDARY
SEXUAL
CHARACTERS
Normal Poor
HEART SIZE May be enlarged Small
GOITRE May be present Absent
SOFT TISSUE
EDEMA
Marked Absent
BLOOD
PRESSURE
Normal or High Low
CHOLESTEROL Increased Normal
TSH High Low
9. PRIMARY SECONDARY
PLASMA CORTISOL Normal Low
TRH STIMULATION
TEST
Exaggerated Response No response
THYROID AUTO
ANTIBODIES
May be present Absent
TO DIAGNOSE PRIMARY AND SECONDARY
HYPOTHYROIDISM CLINICALLY, ONE SHOULD ALWAYS
EXAMINETHE SKIN, HAIR, SECONDARY SEXUAL
CHARACTERISTICS AND SOFT TISSUE EDEMA
10. Hashimoto’s Thyroiditis
Most common cause of goitrous
hypothyroidism in iodine sufficient parts of the
world
Characterized by thyroidal lymphocytic
infiltration with germinal centre formation,
follicular damage or destruction with fibrosis
Goitre develops gradually and is firm in
consistency
Presence of anti TPO and anti thyroglobulin
antibodies favours the diagnosis
History of other auto immune disorders like
rheumatoid arthritis, pernicious anemia,
diabetes mellitus should be ascertained
12. Clinical Features
Largely due to the reduced metabolic rate
and deposition of glycosaminoglycans
(GAG) in different body compartments
Myxoedema refers to the boggy
appearance of the skin and subcutaneous
tissues in the patients with severe
hypothyroid state
Skin is pale and cool, reduction in sweat
and sebaceous secretions causing dryness
and coarseness
13. GAG deposition in the larynx and
pharynx leads to hoarseness of voice
Cardiovascular involvement causes
decreased cardiac output, narrowing of
pulse pressure and increased systemic
vascular resistance causing diastolic
hypertension. Pericardial effusion may
occur
Modest weight gain despite reduced
appetite and constipation due to reduced
gut peristalsis
14. In adult women, decreased libido, failure
of ovulation, polymenorrhoea,
menorrhagia and decreased fertility may
be seen
In men, decreased libido, oligospermia and
impotence may result
These are though to result because of
hyperprolactinemia as prolactin is also
underTRH control
15. A child with congenital hypothyroidism is
sluggish and may present with prolonged
physiological jaundice, meconeum ileus,
umbilical hernia, feeding difficulties, dry
scaly skin and a large tongue
Cretinism: severe hypothyroidism of
infancy
X Ray Pelvis will reveal dysgenesis of
the femoral capital epiphysis, which is
pathognomonic of hypothyroidism in
infancy and childhood
16. Signs and Symptoms
SYMPTOMS
Lethargy
Weight gain
Constipation
Slowed mentation, forgetfulness
Depression
Hair loss
Dry skin
Easy bruising
Menstrual abnormalities
Neck enlargement/ Goitre
17. SIGNS-
Goiter
Low blood pressure and slow pulse
Hair thinning or loss
Dry skin
Confusion
Depressed affect
Non pitting edema
Hung up reflexes
18. DIAGNOSIS
Based on the finding of a low free
thyroxine (T4) level, usually with an
elevation in the TSH levels
For patients with hypothyroidism due to
pituitary dysfunction (secondary
hypothyroidism), both fT4 and TSH are
low
There is no role of thyroid scans or
iodine uptake testing in patients with
hypothyroidism
19. TREATMENT
Thyroxine replacement
The usual dose required to achieve full
replacement is between 100-150 ug/day
For patients with known heart disease or who are
at risk of it, doses are started at 25-50 ug with
increases of 25 ug every 4-6 weeks guided by
TSH levels
Young patients who are otherwise normal can be
started at doses of 100 ug/day
Patients with aTSH<=10.0 do not usually
require any therapy
20. MONITORING
In general, once a patient receives a full
replacement dose of T4 (usually between
100-150 ug/day) and has aTSH
consistently in the normal range, there is
little likelihood that their thyroid
requirement will change over time
There is no evidence to show the need of
re testing to ensure patients are
euthyroid in such a sub group of patients
21. BecauseT4 andT3 are highly protein bound,
any condition where a patient’s serum
protein status changes, prompt testing is
advocated
This includes conditions that lower serum
protein levels such as liver disease,
nephrotic syndrome or malnutrition or
increase them like pregnancy or estrogen
therapy
22. Patients with subclinical
hypothyroidism (mildly elevatedTSH
and a normalT4) also benefit from their
annual testing of fT4 levels.
Approximately 10% of such patients
progress to hypothyroidism within 3 yrs
of diagnosis.Thereby annual testing is
advocated.
23. COMPLICATIONS
Most complications are associated with
under or over treatment
Inadequately treated subjects are at a higher
risk of cardiac disease
Over treatment increases the risk of atrial
fibrillation and osteoporosis
Hashimoto’s thyroiditis is associated with
other auto immune diseases like Addison’s
disease, pernicious anemia, vitiligo.They are
also at a higher risk for the future
development of lymphoma
24. De Quervain’s Thyroiditis
Also known as sub acute/ viral/ granulomatous giant
cell thyroiditis
Most likely viral in origin
Presents with neck pain, which may radiate to the neck
or mandible
Hoarseness, dysphagia and signs of thyrotoxicosis may
be present
Thyroid gland is tender and firm
Histopathologically a well developed follicular lesion
that comprises a central core of colloid and
surrounded multi nucleate giant cells is characteristic
ESR is high and RAIU is low
Nearly always self limiting
25. Post Partum Thyroiditis
It is the occurrence of thyrotoxicosis,
hypothyroidism or thyrotoxicosis followed
by hypothyroidism in the 1st post partum
year, in women without overt thyroid
disease before pregnancy
Occurs in 8-10% women post partum
Upto 30% are anti TPO antibody positive
Painless and self limiting
Likely to recur in subsequent pregnancies
Increased risk of developing permanent
primary hypothyroidism in future
26. Reidel’s Thyroiditis
Characterized by the fibrosis of the thyroid
and adjacent structures
Occurs in middle aged women
Stony hard, immobile goitre resulting in
pressure symptoms due to the compression of
the trachea, oesophagus and the recurrent
laryngeal nerve
One third patients have hypothyroidism
Surgical removal is indicated when pressure
symptoms are present
Glucocorticoids have beens used for
treatment because of the their anti
inflammatory effect
27. Myxoedema Coma
Ultimate stage of severe long standing
untreated hypothyroidism
Often precipitated by stroke, infection,
myocardial infraction, sedative drugs or
exposure to cold
Treatment is started on the basis of clinical
suspicion. Initially the precipitating condition
needs to be identified and treated, and general
suppostive measures instituted
Clinical features include altered sensorium
(coma), subnormal temperature, bradycardia,
hypotension and features of severe myxoedema
28. Mortality of this condition is related to the
severity of hypothermia
Throxine 500 ug is given iv stat followed by
100 ug iv daily (given through nasogastric tube
if intravenous formulation is not available)
Glucocorticoid replacement with iv
hydrocortisone (5-10 mg/hour) should also be
given
External heating should not be done as it
causes cutaneous vasodilatation, which
increases the strain on the heart
Despite aggressive management, mortality
approaches 50%
29. Euthyroid Sick Syndrome: in severely ill
patients during acute physiological stress,
the patients may have mildly elevatedTSH
levels and do not require thyroid
replacement.The levels settle within a few
weeks of recovery and may sometimes be
difficult to distinguish from pre existing or
new onset hypothyroidism.
32. Q1: the best marker to diagnose
thyroid related disorder is:
A. T3
B. T4
C. TSH
D. Thyroglobulin
33. Q2: the lab investigation of a patient
shows decreasedT3,T4 and TSH. It
cannot be?
A. Primary hypothyroidism
B. Panhypopituitarism
C. Liver Disease
D. None
34. Q3: the most common cause of
thyroiditis is?
A. Reidel’s thyroiditis
B. Hashimoto’s thyroiditis
C. Subacute thyroiditis
D. Viral thyroiditis
35. Q4: all of the following are true of
de Quervain’s thyroiditis except?
A. Pain
B. Increased ESR
C. Increased radio active iodine uptake
D. Fever
36. Q5: Hurthle cells are seen in?
A. Agranulomatous thyroiditis
B. Hashimoto’s thyroiditis
C. Papillary carcinoma thyroid
D. Thyroglossal cyst
37. Q6: Hung up ankle jerk is seen in?
A. Hypothyroidism
B. Hyperthyroidism
C. Diabetes Mellitus
D. Acromegaly
38. Q7:All of the following are painless
conditions except?
A. Hashimoto’s thyroiditis
B. De Quervain’s thyroiditis
C. Reidel’s thyroiditis
D. Post partum thyroiditis
39. Q8:All of the following are features
of hypothyroidism except?
A. Sinus bradycardia
B. Diastolic hypertension
C. Systolic hypertension
D. Pericardial effusion
40. Q9:All of the following are features
of primary hypothyroidism except?
A. Menorrhagia
B. Goitre
C. increasedTSH
D. Poor secondary sexual characters