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YEAR 2: CSI > Under-active thyroid > Flashcards

Under-active thyroid Flashcards

1
Q

How is fatigue different from tiredness?

A

Fatigue is when tiredness that is overwhelming and cannot be easily relieved.

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2
Q

What are some causes of fatigue?

A
  • Anaemia
  • Sleep apnoea
  • Underactive thyroid
  • Coeliac disease
  • Chronic fatigue syndrome
  • Diabetes
  • Glandular fever (mono -> EBV)
  • Depression
  • Restless Leg syndrome
  • Generalised anxiety disorder (GAD)
  • Vitamin D deficiency
  • Insomnia
  • Malignancies
  • Chronic Heart failure
  • Infections
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3
Q

What relevant investigations can be carried out after history/ physical examination, to find out reason for tiredness?

A
  • FBC
  • TFTs
  • HbA1c
  • Urea and electrolytes
  • Vitamin D
  • CRP
  • Coeliac screen
  • Autoimmune screen
  • EBV serology (Epstein Barr Virus causes glandular fever)
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4
Q

What are the symptoms of an under active thyroid?

A
  • fatigue
  • weight gain
  • dry skin
  • constipation
  • cold intolerance
  • bradycardia
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5
Q

What are the normal ranges in TFT?

A
  • TSH: 0.5-5.0 mlU/L
  • T3: 0.9-2.8 nmol/L
  • T4: 5.0- 12.0 microg/dL
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6
Q

What are the causes of primary hypothyroidism?

A
  • autoimmune (Hashimoto’s)

- iodine deficiency

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7
Q

In Hashimoto’s disease, auto-antibodies against which molecule are produced?

A

TPO enzyme -> involved in the synthesis of T3/4 (anti-TPO)

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8
Q

What happens to the levels of hormone in Hashimoto’s disease?

A
  • TSH increases (no negative feedback)

- T3/T4 decrease (reduced synthesis of hormones)

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9
Q

Which cells contain MHC I molecules?

A

All cells in the body

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10
Q

Which cells contain MHC II molecules?

A

APCs

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11
Q

What receptor in the T cell binds to the MHCII molecule on the APC?

A

TCR

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12
Q

What cell has the B7 receptor and what does it bind to?

A

APCs: B7 receptors and they bind to CD28 receptors on T cells

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13
Q

What does the TCR bind to on B cells?

A

BCR

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14
Q

What cell has the CD40L receptor and what does it bind to?

A

T cells: CD40L receptor which bind to CD40 receptors on B cells

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15
Q

What cells produce anti-TPO antibodies?

A

B cells

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16
Q

Describe how T cells recognise non-self antigens.

A
  1. APCs present antigen using their MHC II molecules onto the TCRs of T helper cells,
  2. In order for the T cells to be completely activated, they need to be co-stimulated.
17
Q

What is T cell co-stimulation?

A

A secondary signal which activates T cells -> in this case, it is the binding of B7 to CD28 receptors on T cells.

18
Q

What happens in Hashimoto’s?

A
  1. APCs present TPO to T cells which recognise it as an non-self antigen.
  2. T cells gets co-stimulated (B7 -> CD28)
  3. Activated T helper cells activate B cells by TCR-BCR binding.
  4. B cells are co-stimulated.
  5. B cells differentiate into plasma cells and produce anti-TPO.
19
Q

What is B cell co-stimulation?

A

A secondary signal which activates B cells -> in this case, it is the binding of CD40L receptor to CD40 on B cells.

20
Q

What do the anti-TPO antibodies result in?

A

They bind to and kill thyrocytes.

21
Q

What other cells are involved in killing thyrocytes?

A

Cytotoxic T cells

22
Q

What is immune tolerance?

A

Prevention of immune response to self antigens.

23
Q

How do granulocytes (neutrophils etc.) show immune tolerance?

A

They only detect
- DAMPs
- PAMPs
so cannot kill self-cells. They are part of the innate immune response.

24
Q

How do lymphocytes (B + T cells) develop tolerance?

A

In early development, they are exposed to a microcosm of almost every single protein in the body and are trained not to kill self-proteins.

25
Q

How do NK cells (part of innate and adaptive immune response) show immune tolerance?

A

They only become activated in response to an absence of MHC I molecules on their surface.

26
Q

Why does autoimmunity occur?

A

Unknown but it could be contributed to…

  • genetics
  • environment
  • molecular mimicry
27
Q

What is molecular mimicry?

A
  1. Pathogens may have a structure which is similar to self-proteins in the body.
  2. The body may produce antibodies against these pathogenic antigens.
  3. Due to the self-proteins having a similar shape to the pathogenic antigens, the antibodies may attack them too leading to autoimmunity.
28
Q

What are some of the different types of tiredness?

A
  • drowsiness
  • shortness of breath
  • weakness
  • exertional tiredness
29
Q

What are some red flag symptoms you must screen for if someone presents with tiredness?

A
  • lymphadenopathy
  • weight loss
  • malignancy features (FLAWS)
  • joint pains
  • focal neurology (problems with nerves/CNS)
  • infective symptoms
30
Q

How is primary hypothyroidism treated?

A

Levothyroxine (T4) tablets

31
Q

How is treatment affected by pregnancy?

A

Dose of Levothyroxine will probably increase because the thyroid hormone is important for the development of the thyroid gland in the foetus.

32
Q

What can increase absorption of Levothyroxine?

A

Grapefruit

33
Q

What are the 2 types of Hashimoto’s?

A
  • Goitrous Hashimoto’s thyroiditis: WBCs attack thyroid and cause inflammation of tissue.
  • Atrophic Hashimoto’s thyroiditis: atrophy of thyroid as TSH receptors become blocked by the antibodies.
34
Q

What is subclinical hypothyroidism/ Mild thyroid failure?

A

When level of hypothyroidism is so slight that there are no obvious symptoms and it can only be detected by blood tests.

35
Q

Describe the TSH and T4 levels in subclinical hypothyroidism.

A
  • slightly raised TSH level

- normal FT4 level

YEAR 2: CSI (8 decks)

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