Thyroid Flashcards
1
Q
Where is the thyroid gland located?
A
Close to thyroid cartilage with two lateral lobes connected by the thyroid isthmus.
2
Q
What is the origin of the thyroid gland?
A
Derived from the median bud of the pharynx (thyroglossal duct).
3
Q
What are para-follicular cells (C-cells) derived from?
A
Derived from the neural crest.
4
Q
At what gestational week does T4 & T3 synthesis occur?
A
12 weeks of fetal life.
5
Q
What anatomical structures are medial to the thyroid gland?
A
Larynx, pharynx, trachea, esophagus, and recurrent laryngeal nerve.
6
Q
What are the main arteries supplying the thyroid gland?
A
- Superior thyroid artery
- Inferior thyroid artery
- Thyroidea ima artery (occasionally)
7
Q
What is the venous drainage of the thyroid gland?
A
- Superior thyroid vein to internal jugular vein
- Middle thyroid vein to internal jugular vein
- Inferior thyroid vein to innominate veins
8
Q
What is the nerve supply of the thyroid gland?
A
- Sympathetic innervations from cervical plexus
- Parasympathetic supply from vagus nerve
9
Q
What is iodide trapping?
A
The process of iodide uptake by thyroid follicular cells.
10
Q
What are the physiological effects of thyroxin hormone?
A
- Increased basal metabolic rate
- Increased mobilization of lipids
- Increased protein breakdown
- Increased heart rate
- Increased gastrointestinal motility
- Weakness of skeletal muscles
- Excessive sweating
- Nervous irritability
11
Q
True or False: TSH levels are elevated in hypothyroidism.
A
True.
12
Q
What is the normal range for total serum thyroxin (T4)?
A
55-150 mmol/l.
13
Q
What are the types of goiter?
A
- Simple goiter
- Endemic goiter
- Sporadic goiter
- Multinodular goiter
14
Q
What causes simple goiter?
A
- Iodine deficiency
- Enzymatic deficiency
- Goitrogens
15
Q
What are the stages of simple goiter?
A
- Diffuse homogenous hyperplasia
- Simple colloid goiter
- Nodular goiter
16
Q
What are the complications of simple nodular goiter?
A
- Tracheal obstruction
- Secondary thyrotoxicosis
- Malignancy
- Hemorrhage
- Cyst formation
- Calcification
17
Q
What is the treatment for diffuse hyperplastic goiter?
A
Thyroxine 0.2 mg/day for several months, then tapering to 0.1 mg/day for years.
18
Q
What are the types of toxic goiter?
A
- Diffuse toxic goiter (Grave’s disease)
- Toxic nodular goiter (Plummer’s disease)
- Toxic nodule
19
Q
What characterizes Grave’s disease?
A
Diffuse enlargement of the thyroid gland with symptoms of thyrotoxicosis.
20
Q
What is exophthalmos?
A
Outward bulging of the eye due to fatty fibrous tissue behind the orbit.
21
Q
True or False: Exophthalmos is always due to fluid deposition.
A
False.
22
Q
What are the symptoms of hyperthyroidism?
A
- Tiredness
- Emotional lability
- Heat intolerance
- Weight loss
- Excessive appetite
- Palpitations
- Diarrhea
23
Q
What is the clinical presentation of simple nodular goiter?
A
Nodular, non-tender gland, with cosmetic disfigurement or obstructive symptoms.
24
Q
What is the purpose of thyroid function tests?
A
To evaluate T3, T4, and TSH levels to exclude thyrotoxicosis.
25
What is the significance of the thyroid stimulating antibody (TsAb)?
Stimulates release of T3 and T4 in Grave's disease.
26
What is the age group commonly affected by Plummer's disease?
Middle and old age.
27
What is the primary symptom of Grave's disease?
Diffuse enlargement of the thyroid gland
## Footnote
Grave's disease is an autoimmune disorder that leads to hyperthyroidism.
28
What type of thyroid disease is associated with nodular goiter?
Plummer’s disease
## Footnote
Plummer's disease is characterized by hyperfunctioning nodules in the thyroid.
29
What are the two types of disease onset for thyroid conditions?
Abrupt and gradual
## Footnote
The onset can vary significantly among different thyroid diseases.
30
What are the two courses of thyroid disease?
Remissions & exacerbations and steady course
## Footnote
Different thyroid conditions may follow different clinical courses.
31
What is the typical thyroid function test result in hyperthyroidism?
High thyroxin and very low TSH
## Footnote
Thyroid function tests are essential for diagnosing thyroid disorders.
32
List the three treatment options for thyroid diseases.
* Medical treatment
* Radioactive iodine
* Surgery
## Footnote
Each treatment option has specific indications and contraindications.
33
What is the aim of medical treatment for hyperthyroidism?
To restore euthyroid status
## Footnote
Medical treatment is often the first-line approach for hyperthyroidism.
34
Name one drug used in medical treatment of hyperthyroidism.
Carbimazole
## Footnote
Carbimazole blocks iodine binding to tyrosine.
35
What are the contraindications for medical treatment of hyperthyroidism?
* Secondary toxic goiter
* Solitary toxic nodule
* Retrosternal goiter
## Footnote
These conditions require different treatment approaches.
36
What is the risk associated with radioactive iodine treatment?
Hypothyroidism risk of 5% - 10%
## Footnote
Long-term effects of radioactive iodine can include thyroid insufficiency.
37
What is the indication for surgery in thyroid conditions?
* Primary toxic goiter in young & large gland
* Secondary toxic goiter
* Failure or side effects of medical treatment
* Solitary toxic nodule
## Footnote
Indications for surgery vary based on the patient's condition.
38
What is a common post-operative complication of thyroid surgery?
Hemorrhage
## Footnote
Hemorrhage can lead to respiratory obstruction if not managed properly.
39
What is the main characteristic of Hashimoto’s thyroiditis?
Autoimmune thyroiditis with lymphocytic infiltration
## Footnote
It is the most common cause of goitrous hypothyroidism in iodine-sufficient areas.
40
What is Riedel’s thyroiditis also known as?
Massive fibrous thyroiditis
## Footnote
It involves extensive fibrous replacement of thyroid tissue.
41
What type of thyroid cancer is most common?
Papillary carcinoma
## Footnote
It accounts for 75%-85% of all thyroid cancer cases.
42
What are the risk factors for thyroid cancer?
* Multinodular goitre
* Ionizing radiation
* Hashimoto thyroiditis
* Multiple endocrine neoplasia (type II)
## Footnote
These factors increase the likelihood of developing thyroid malignancies.
43
What are common symptoms of acute thyroiditis?
* Pain
* Fever
* Dysphagia
* Swelling
## Footnote
Acute thyroiditis often occurs after a bacterial infection.
44
What is the treatment for subacute thyroiditis?
* Aspirin
* NSAIDs
* Corticosteroids
## Footnote
Treatment focuses on managing inflammation and pain.
45
What imaging technique is used to investigate solitary thyroid nodules?
Thyroid ultrasonography
## Footnote
Ultrasound helps determine the characteristics of thyroid nodules.
46
What is the prognosis for papillary carcinoma of the thyroid?
Five-year survival = 90-95%
## Footnote
Papillary carcinoma has a favorable prognosis compared to other types.
47
What is the typical age group affected by Hashimoto's thyroiditis?
30-40 years
## Footnote
Hashimoto's thyroiditis is more common in middle-aged women.
48
Fill in the blank: The primary treatment for hypothyroidism is _______.
Thyroxine replacement
## Footnote
This treatment is essential for managing hypothyroidism.
49
What is a common complication of subtotal thyroidectomy?
Thyroid insufficiency in 20-45% of cases
## Footnote
Patients may require lifelong thyroid hormone replacement after surgery.
50
What is the significance of fine needle aspiration cytology (FNAC) in thyroid conditions?
To rule out malignancy
## Footnote
FNAC is a critical diagnostic tool for evaluating thyroid nodules.
51
What is the role of beta-blockers in the treatment of hyperthyroidism?
Inhibits cardiovascular effects of thyroxin
## Footnote
Beta-blockers help manage symptoms like tachycardia.
52
What is the characteristic gross appearance of papillary carcinoma?
Variably sized, solitary or multifocal, solid infiltrating tumor with a granular cyst surface and degenerative cystic changes
## Footnote
Papillary carcinoma features nuclear overlapping, nuclear clearing, nuclear grooves, nuclear pseudoinclusions, and psammoma bodies.
53
What are psammoma bodies?
Laminated calcific densities found in papillary carcinoma
## Footnote
These bodies are associated with a favorable prognosis.
54
What is the peak incidence age range for follicular carcinoma?
40s-50s
## Footnote
Follicular carcinoma is more common in females than males with a ratio of 3:1.
55
How does follicular carcinoma typically present clinically?
As a solitary nodule
## Footnote
It has a more rapid growth rate than papillary carcinoma.
56
What is the prognosis for follicular carcinoma at 10 years?
60% survive
## Footnote
Follicular carcinoma usually does not spread to lymph nodes but can metastasize to lungs, bones, or liver.
57
What are the histological features of follicular carcinoma?
Uniform colloid-filled follicles, capsular invasion, vascular invasion
## Footnote
Diagnosis requires demonstration of cellular invasion.
58
What is medullary carcinoma and from which cells does it originate?
A neuroendocrine neoplasm originating from parafollicular cells (C-cells)
## Footnote
Medullary thyroid carcinoma accounts for about 5% of thyroid cancers.
59
What hormones do medullary carcinoma tumor cells secrete?
Calcitonin and carcinoembryonic antigen (CEA)
## Footnote
Calcitonin regulates calcium levels in blood, while CEA is associated with several cancers.
60
What are the two clinical types of medullary carcinoma?
Sporadic and familial (associated with MEN syndrome IIa or IIb)
## Footnote
Sporadic MTC occurs mostly in older adults, while familial cases often develop during childhood or early adulthood.
61
What are the gross features of medullary carcinoma?
Solitary nodule or multiple lesions involving both lobes of the thyroid
## Footnote
Familial cases may show C-cell hyperplasia.
62
What characterizes anaplastic carcinoma?
Rare, aggressive form of thyroid cancer that is undifferentiated
## Footnote
It is predominantly found in older adults and is slightly more common in females.
63
What are common symptoms of anaplastic carcinoma?
Dyspnea, dysphagia, hoarseness of voice
## Footnote
It metastasizes to regional lymph nodes and distant organs such as lungs.
64
What is Hürthle cell carcinoma also known as?
Oxyphil cell carcinoma
## Footnote
It is a subtype of follicular carcinoma, accounting for about 4% of thyroid cancers.
65
What is the association between thyroid lymphoma and Hashimoto’s thyroiditis?
There is an increased association between lymphoma and Hashimoto’s thyroiditis
## Footnote
Primary thyroid lymphoma is rare but should be considered in patients with rapidly growing goiters.
66
What is the first step after a nodule is found during examination?
Referral to an endocrinologist, thyroidologist, or otolaryngologist
## Footnote
An ultrasound is typically performed to confirm the presence of a nodule.
67
What does fine needle biopsy (FNB) assess?
Whether the nodule is malignant
## Footnote
FNB is described as cost-effective, sensitive, and accurate.
68
What is the treatment for benign thyroid nodules?
Thyroxine therapy to suppress thyroid-stimulating hormone
## Footnote
Patients should be reevaluated in 6 months.
69
What is the primary use of radioactive iodine-131 (131I)?
Ablation of residual thyroid tissue after surgery and treatment of thyroid cancer
## Footnote
It is not beneficial for patients with medullary, anaplastic, and most Hürthle cell cancers.
70
What is the role of external irradiation in thyroid cancer treatment?
Useful only in selected locally invasive thyroid carcinomas and anaplastic carcinoma
## Footnote
Chemotherapy has limited usefulness currently.
