Hypothyroidism Flashcards
1
Q
A
2
Q
Stages of Thyroid Gland Development
A
- Fetal thyroid gland
- Neonatal thyroid gland
- Childhood thyroid gland
3
Q
Embryological Development of Thyroid Gland
A
4
Q
Embryological Development of Thyroid Gland
- Time
A
Thyroid gland develops in the ist month of life (5th - 7th week of gestation)
5
Q
Embryological Development of Thyroid Gland
- Origin
A
It develops by proliferation & invagination of the endoderm of the foregut and 4th, 5th pharyngeal pouch which forms a pouch in the floor of pharynx, migrates downward
6
Q
Embryological Development of Thyroid Gland
- Course
A
- The thyroid becomes attached to the pharynx by the thyroglossal duct
7
Q
Embryological Development of Thyroid Gland
- Clinical Significance
A
Ectopic Thyroid Gland
8
Q
Pathogenesis of Ectopic Thyroid Gland
A
- Ectopic thyroid tissue results from a lack of caudal migration of the thyroid gland and is thus, usually located along the normal path of thyroid gland descent
9
Q
Types of Ectopic Thyroid Gland
- Lingual
A
- The entire thyroid gland fails to descend to its normal adult orthotopic site.
- The descent is completely arrested at the level of the base of the tongue
10
Q
Do Patients with Ectopic Thyroid Gland have another thyroid?
A
11
Q
Dx of Ectopic Thyroid Gland
A
- Ectopic thyroid is mainly diagnosed with a thyroid scan, which can localize all ectopic foci that take up radioisotope outside the native thyroid location in the neck
12
Q
Sequence of Intrauterine Thyroid Activity
A
13
Q
Fetus depend on maternal thyroid hormones in ……
A
1st half of gestation
14
Q
- Maternal hypothyroidism has deleterious effects on …..
- There should be biochemical screening of women who have a personal or family history of thyroid disease
A
offspring intellectual development (Cretinism)
15
Q
Def of Cretinism
A
- it’s a condition of severely physical, mental & sexual developmental disorder due to untreated congenital hypothyroidism usually with underlying maternal hypothyroidism
16
Q
Changes in T4 & TSH
A
17
Q
Changes in T4 & TSH
- At Birth
A
18
Q
Changes in T4 & TSH
- Later
A
19
Q
Steps of Thyroid Hormone Synthesis
VIP
A
20
Q
Regulation of Thyroid Gland Function
A
21
Q
Wolff-Chaikoff Effect
A
22
Q
Physiologic effects of T3 & T4
A
23
Q
Incidence of Congenital Hypothyroidism
A
24
Q
Etiology of Congenital Hypothyroidism
A
25
Etiology of **Congenital Hypothyroidism**
- 1ry
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Etiology of **Congenital Hypothyroidism**
- 2ry
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Etiology of **Congenital Hypothyroidism**
- 3ry
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Etiology of **Congenital Hypothyroidism**
- End-Organ Resistance
29
Etiology of **1ry Hypothyroidism**
**Conenital:**
- Thyroid Agenesis (90%)
- Dyshormonogenesis
- Antenatal Goitrogens
**Acquired:**
- Hashimotomo
- Iatrogenic
- etc .....
30
Etiology of **1ry Hypothyroidism**
- Thyroid Agenesis
Aplasia, hypoplasia or ectopic
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Etiology of **1ry Hypothyroidism**
- Dyshormonogenesis
32
Etiology of **1ry Hypothyroidism**
- Antenatal Goitrogens
- Maternal antithyroid drugs "lodide & carbimazole".
- Maternal radioactive iodine in the 1st trimester
- Maternal diet (Endemic goiter / Cretinism)
- Maternal disease (AIT.> (TRB-Ab, TG-Ab)
33
Etiology of **1ry Hypothyroidism**
- Acquired
- Hashimoto's thyroiditis (chronic lymphocytic thyroiditis).
- Surgical excision.
- Irradiation to neck.
- iodine in diet (Endemic goiter).
34
Etiology of **1ry Hypothyroidism** may also be classified as .......
Transient & Permenant
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Etiology of **1ry Hypothyroidism**
- Transient Causes
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Etiology of **1ry Hypothyroidism**
- Premnant Causes
- Most common
- Long term intellectual defect outcome
37
CP of **Congenital Hypothyroidism**
- During early weeks of life
- With Growth
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CP of **Congenital Hypothyroidism**
- Early Weeks of Life
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CP of **Congenital Hypothyroidism**
- Hx
- Maternal (Antenatal) history
- Family history (Hereditary hypothyroidism)
40
CP of **Congenital Hypothyroidism**
- Ex
- Apgar score for early suspicion of hypothyroidism
- Thyroid gland examination
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CP of **Congenital Hypothyroidism**
- Biochemical tests
- Neonatal screening for congenital hypothyroidism
- Confirmatory lab test
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CP of **Congenital Hypothyroidism**
- APGAR Score for hypothyroidism
**(VIP)**
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CP of **Congenital Hypothyroidism**
- Others
- Little horse cry
- Always sleep
- Pulse & Respiratory rate
- Feed Feeding difficulties & Chocking
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CP of **Congenital Hypothyroidism**
- X-ray findings
- Absence of ossification centers on lower end of femur
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CP of **Congenital Hypothyroidism**
- Later with Growth
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CP of **Congenital Hypothyroidism**
- Coarse Features
47
Most children with congenital hypothyroidism do not have symptoms at the time of birth because ......
because the placenta supplies the fetus with maternal thyroid hormone.
48
For this reason, neonatal screening is vital even if children are asymptomatic.
....
49
Irreversible intellectual disabilities can be avoided through early initiation of adequate therapy
...
50
Investigations for **Congenital Hypothyroidism**
**Lab:**
- TFT
- Abs
- Cholesterol
**Rad:**
- US
- Thyroid Scan
- X-Ray
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Investigations for **Congenital Hypothyroidism**
- Labs
**Lab:**
- TFT
- Abs
- Cholesterol
52
Investigations for **Congenital Hypothyroidism**
- Thyroid Function Tests
53
Investigations for **Congenital Hypothyroidism**
- Radioactive T3 resin uptake (RU)
Normally 26 - 35 % (depend on the unbound protein binding globulin)
54
Investigations for **Congenital Hypothyroidism**
- T4 Index
Total T4 x T3 RU (Normally 1.3 - 4.3)
55
Investigations for **Congenital Hypothyroidism**
- Additional Labs
- Anti-thyroglobulin and anti-microsomal antibodies
- T Serum cholesterol
56
Investigations for **Congenital Hypothyroidism**
- Rad
**Rad:**
- US
- Thyroid Scan
- X-Ray
57
Investigations for **Congenital Hypothyroidism**
- US
58
Investigations for **Congenital Hypothyroidism**
- Thyroid Scan
59
Investigations for **Congenital Hypothyroidism**
- X-ray
60
Neonatal Screening for **Congenital Hypothyroidism**
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Neonatal Screening for **Congenital Hypothyroidism**
- Def
- A national program for early diagnosis of congenital hypothyroidism to prevent mental retardation
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Neonatal Screening for **Congenital Hypothyroidism**
- Technique
It's done by blood sample (heal pin prick) en filter paper which is collected and examined for TSH or T4
63
Neonatal Screening for **Congenital Hypothyroidism**
- Timing
- Sample is taken 3-7 days after birth (to avoid TSH surge during the 1st 3 days after birth).
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Neonatal Screening for **Congenital Hypothyroidism**
- Appraoches
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Neonatal Screening for **Congenital Hypothyroidism**
- Screening by TSH
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Neonatal Screening for **Congenital Hypothyroidism**
- Screening by T4
T4 < 6.6 mg/dl is diagnostic
67
If screening is positive, ........
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Start treatment at once till the results of investigation.
...
69
If the reinvestigation is:
* Positive → .......
* If not → .......
- Continue TTT
- Stop TTT
70
Interpretation of **Thyroid Screening**
71
Interpretation of **Thyroid Screening**
72
Interpretation of **Thyroid Screening**
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Interpretation of **Thyroid Screening**
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- Persistent elevated TSH despite of normal size thyroid gland should be treated as congenital hypothyroidism.
...
75
- Treatment should continue until 2 years of age "At which myelination of CNS is complete" & then repeat the investigations.
....
76
- Occasionally, an infant with congenital hypothyroidism may escape detection in newborn screening programs. These infants must be diagnosed on clinical basis
...
77
TTT of **Congenital Hypothyroidism**
78
TTT of **Congenital Hypothyroidism**
- Principles
- Start treatment within 2-3 weeks after birth.
- Start treatment after withdrawal of blood for investigation & I123 thyroid scan.
79
TTT of **Congenital Hypothyroidism**
- The level of cord T4 & the degree of delay of bone age at birth is highly correlated with the neurodevelopmental delay in congenital hypothyroidism
...
80
TTT of **Congenital Hypothyroidism**
- Dose of L-Thyroxine
81
TTT of **Congenital Hypothyroidism**
- Monitoring of L-Thyroxine
82
TTT of **Congenital Hypothyroidism**
- Early Signs of Improvement
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TTT of **Congenital Hypothyroidism**
- Goals of Therapy
84
TTT of **Congenital Hypothyroidism**
- Follow up
85
TTT of **Congenital Hypothyroidism**
- SE of L-Thyroxine
86
Prognosis of **Congenital Hypothyroidism**
