Hyperthyroidism, Hypothyroidism and Thyroiditis Flashcards
1
Q
What is secondary thyroid disease?
A
Hypothalmic or pituitary disease
(this will indirectly impact the thyroid)
2
Q
What is a goitre?
A
A swelling in the neck from an enlarged thyroid
3
Q
By what other name is thyrotropin known?
A
Thyroid stimulating hormone
4
Q
Which cells secrete TSH?
A
Thyrotroph cells
(anterior pituitary)
5
Q
How are T3/T4 produced?
A
- Postive stimulus on hypothalamus
- Thyroid releasing hormone secreted
- TRH acts on anterior pituitary
- Thyroid stimulating hormone secreted
- TSH acts on thyroid
- T3/T4 produced
6
Q
At which pointsin the hypothalmic-pituitary-thyroid axis can T3/T4 self regulate their release?
A
- Act on hypothalamus to reduce TRH release
- Act on pituitary to reduce TSH release
7
Q
What are the thyroid hormone levels like in primary hypothyroidism?
A
Free T3/4 low
TSH high
8
Q
What are the thyroid hormone levels like in primary hyperthyroidism?
A
Free T3/4 high
TSH low
9
Q
What are the thyroid hormone levels like in secondary hypothyroidism?
A
Free T3/4 low
TSH low (or “normal” within the context)
10
Q
What are the thyroid hormone levels like in secondary hyperthyroidism?
A
Free T3/4 high
TSH high (or “normal” in the context)
11
Q
Hypothyroidism is the product of any disorder that results in what?
A
Insufficient thyroid hormone secretion
12
Q
What is myxoedema?
A
Severe hypothyroidism
13
Q
Pretibial myxoedema is a rare clinical sign of which condition?
A
Graves’ disease
14
Q
Hypothyroidism is most common in which ethnic background?
A
White caucasian
15
Q
Chronic thyroiditis is known by which other term?
A
Hashimoto’s thyroiditis
16
Q
What can cause chronic goitrous thyroiditis (Hashimoto’s)?
A
- Iodine deficiency
- Drugs (amiodarone, lithium)
- Maternal transmission (antithyroid drugs)
- Hereditary biosynthetic defects
17
Q
Non-goitrous primary hypothyroidism is known by which other term?
A
Atrophic thyroiditis
18
Q
What may induce non-goitrous primary hypothyroidism?
A
- Post-ablative therapy (radioiodine, surgery)
- Post-radiotherapy (e.g. lymphoma treatment)
- Congenital developmental defect
19
Q
Self-limiting primary hypothyroidism may be the result of which 3 main things?
A
- Withdrawal of antithyroid drugs
- Subacute thyroiditis with transient hypothyroidism
- Post-partum thyroiditis (immediately following birth)
20
Q
What are some causes of secondary hypothyroidism?
A
- Infection
- Infiltrative
- Malignant
- Traumatic
- Congenital
- Cranial radiopathy
- Drug-induced
21
Q
What is the most common cause of autoimmune hypothyroidism in the western world?
A
Hashimoto’s thyroiditis
22
Q
How is autoimmune (Hashimoto’s) thyroiditis characterised?
A
- Antibodies against thyroid peroxidase (TPO)
- T cell infiltrate and inflammation
23
Q
Which parts of the body are affected in hypothyroidism?
A
- Hair and skin
- Neurological
- Cardio
- Respiratory
- GI
- Gynae/reproductive
- Metabolic
24
Q
How are the hair and skin affected in hypothyroidism?
A
- Coarse, sparse hair
- Dull expressionless face
- Periorbital puffiness
- Pale cool skin that feels doughy
- Vitiligo
- Hypercarotenaemia
- Pitting oedema
25
How is the cardiovascular system impacted by hypothyroidism?
1. Reduced heart rate
2. Cardiac dilatation
3. Pericardial effusion
4. Worsening heart failure
26
How are metabolic processes affected in hypothyroidism?
1. Hyperlipidaemia
2. Slowed, decreased appetite, weight gain
27
How is the GI system affected in hypothyroidism?
1. Constipation
2. Megacolon and intestinal obstruction
3. Ascities
28
How is the respiratory system affected in hypothyroidism?
1. Deep hoarse voice
2. Macroglossia
3. Obstructive sleep apnoea
29
What is macroglossia?
Abnormally enlarged tongue
30
How is the CNS affected in hypothyroidism?
1. Decreased intellectual or motor activities
2. Depression, psychosis
3. Muscle stiffness, cramps
4. Peripheral neuropathy
5. Prolongation of the tendon jerks
6. Carpal tunnel syndrome
7. Cerebellar ataxia, encephalopathy
8. Decreased visual acuity
31
How is the gynae/reproductive system affected in hypothyroidism?
1. Menorrhagia (heavy periods)
2. Oligo (reduced periods) or amenorrhoea (absent periods)
3. Hyperprolactinaemia (due to increased TRH)
32
What may the results show for the following things in hypothyroidism?
## Footnote
a) Red cell size
b) Creatine kinase
c) LDL
d) Na+
e) Prolactin
a) Macrocytosis (enlarged)
b) Increased CK
c) Increased LDL
d) Decreased Na+ (hyponatraemia)
e) Increased prolactin (hyperprolactinaemia)
33
What are the three thyroid antibodies which ca be detected in Hashimoto's thyroiditis (and Grave's disease)?
1. Anti-thyroid peroxidase (anti-TPO)
2. Anti-thyroglobulin
3. TSH receptor antibody
34
What may occur to a patient with hypothyroidism if restoration of metabolic rate occurs rapidly?
Cardiac arrhythmias
35
What is the treatment for both old and young patients with hypothyroidism?
Levothyroxine
50-100 micrograms (young)
25-50 micrograms (old)
Adjust every 4 weeks based on response
36
Once TSH is stabilised in a hypothyroidism case, how often should it be checked?
Every 12-18 months
37
In secondary hypothyroidism, what should the ;evothyroxine dose be titrated to?
Free T4 levels
(these are more reliable as there is decreased TSH production)
38
Levothyroxine is essentially just \_\_\_
T4
39
Why do dose requirements for levothyroxine (to treat hypothyroidism) increase during pregnancy?
There is increased thyroxine binding globulin
(less T3/4)
40
A myxoedema coma typically affects which agen and sex?
Elderly women
41
What are the findings on ECG for a myxoedema coma?
1. Bradycardia
2. Low voltage complexes
3. Varying degrees of heart block
4. T wave inversion
5. Prolongation of QT interval
42
Co-existing _________ failure is present in 10% of patients with a myxoedema coma
Co-existing **adrenal** failure is present in 10% of patients with a myxoedema coma
43
Why is thyrotoxicosis?
Clinical, physiological and biochemical state arising when tissues are exposed to excess thyroid hormone
44
Which areas of the body are affected by thyrotoxicosis?
1. Hair and skin
2. CNS
3. Vision
4. Cardiac
5. Reproductive
6. Muscles
7. Metabolism
45
How does thyrotoxicosis affect the cardiovascular system?
1. Palpitation and AF
2. Cardiac failure (rare)
46
How does thyrotoxicosis affect the CNS?
1. Anxiety
2. Nervousness
3. Irritability
4. Sleep disturbance
47
How does thyrotoxicosis affect the GI system?
Frequent loose bowel movements
48
How does thyrotoxicosis affect the vision?
1. Lid retraction
2. Diplopia
3. Proptosis (bulging of eye(s))
49
How does thyrotoxicosis affect the hair and skin?
1. Brittle thin hair
2. Rapid fingernail growth
50
How does thyrotoxicosis affect the reproductive system?
Menstrual changes - lighter and less frequent periods
51
How does thyrotoxicosis affect the muscles?
Weakness - especially thighs and upper arms
52
What are two broad causes of thyrotoxicosis associated with hyperthyroidism?
1. Excessive thyroid stimulation
2. Thyroid nodules with autonomous function
53
Excessive thyroid stimulation may be brought about by what?
1. Graves' disease
2. Hashitoxicosis
3. Thyrotropinoma
4. Thyroid cancer
5. Choriocarcinoma (trophoblast tumour secreting hCG)
54
What are the three broad causes of thyrotoxicosis not associated with hyperthyroidism?
1. Thyroiditis
2. Exogenous thyroid hormones
3. Ectopic thyroid tissue
55
What 3 things may induce thyrotoxicosis, thyroiditis, but not hyperthyroidism?
1. De Quervain's thyroiditis
2. Post-partum thyroiditis
3. Drug induced thyroiditis
56
Is smoking related to higher incidence of Grave's disease?
Yes
57
In Grave's disease, how are the following impacted?
a) TSH
b) Free T3/4
a) Decreased TSH
b) Increased free T3/4
58
Which other abnormalities besides TSH and fT3/4 can be notoed on a blood test for an individual with Grave's disease?
1. Hypercalcaemia
2. Raised ALP
3. Leucopenia
4. TSH receptor antibody
59
Graves' disease is associated with ___________ rates of osteoporosis
Graves' disease is associated with increased rates of osteoporosis
60
Which sign, classical of Graves' disease is seen in the picture?
Pretibial myxoedema
61
What is thyroid acropachy and which condition is it associated?
Soft tissue swelling of digits and finger clubbing
Graves' disease
62
Which clinical sign associated with the thyroid is specific to Graves' disease?
Thyroid bruit
63
How can thyroid eye disease (Grave's eye disease) be treated?
Mild - lubricants
Severe - steroids, radiotherapy, surgery
64
How does the thyroid differ in feel in patients with nodular thyroid disease versus Grave's?
It may feel nodular
| (it is smooth in Graves')
65
Nodular thyroid disease results in __________ fT3/4 and a ____________ TSH
Nodular thyroid disease results in **raised** fT3/4 and a **decreased** TSH
66
Nodular thyroid disease is antibody \_\_\_\_\_\_\_\_\_\_\_
Nodular thyroid disease is antibody **negative**
67
What is a thyroid storm?
Severe hyperthyroidism
68
What clinical signs suggest a thyroid storm?
1. Respiratory and cardiac failure
2. Hyperthermia
3. Exaggerated reflexes
4. Post infection or recent thyroid surgery
69
What are the treatments for a thyroid storm?
1. Lugol's iodine
2. Glucocorticoids
3. Propylthiouracil
4. Beta blockers
5. Fluids
70
What is the mechanism for antithyroid drugs?
Inhibition of thyroid peroxidase hence blocking thyroid hormone synthesis
71
What is the first line antithyroid drug?
Carbimazole
72
When would propyllthiouracil be used instead of carbimazole?
Pregnancy
(carbimazole has the risk of aplasia cutis)
73
In which two ways can antithyroid drugs be administered?
1. Dose titration
2. Block and replace
74
What are the main side effects of the antithyroid drugs?
1. Rash, urticaria, arthralgia
2. Cholestatic jaundice (hepatic failure (PTU))
3. Agranulocytosis
75
What is agranulocytosis?
Severe leukopenia
Usually involving neutrophils causing a neutropenia in the circulating blood
76
What is the mechanism for beta blockers in the treatment of hyperthyroidism?
B-adrenoceptor blockade resulting in reduced sympathetic activity
77
What is the beta blocker of choice in the treatment of hyperthyroidism?
Propranolol
78
In which patients with hyperthyroidism may propranolol be unsuitable and what is the alternative?
Asthmatics (can induce bronchospasm)
CCBs instead e.g. diltiazem
79
What is the first line treatment for relapsed Graves' disease and nodular thyroid disease?
Radioiodine
80
What are the main pitfalls in using radioiodine as treatment?
1. Cannot be used in pregancy
2. Contact precautions when on treatment e.g. away from children/pregnant women
3. Increased risk of hypothyroidism
4. May be contraindicated in active eye disease
81
When may a thyroidectomy be useful?
Radioiodine is contraindicated
82
What are the main surgical/anaesthetic risks of a thyroidectomy?
1. Recurrent laryngeal nerve palsy
2. Hypothyroidism
3. Hypoparathyroidism
83
Which drugs may induce thyroiditis?
1. Amiodarone
2. Lithium
84
What is the normal range for TSH?
0.4-4.0mU/L
85
What is the normal range for free T4?
9.8-18.8pmol/l
