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2 ENDOCRINE > Thyroid disease > Flashcards

Thyroid disease Flashcards

1
Q

what is primary thyroid disease

A

disease affecting the thyroid gland itself

can occur with or with our goitre

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2
Q

what is secondary thyroid disease

A

thyroid gland is fine

something else isn’t working eg. hypothalamus or pituitary gland disease

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3
Q

what is TSH

A

a hormone secreted by the pituitary gland to stimulate thyroid hormone secretion in the thyroid

(Also called thyrotrophin)

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4
Q

What percent of thyroid hormone is T4

A

80%

T4 is not active and gets changed to T3 in the cells

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5
Q

What percent of thyroid hormone is T3

A

20%

4x more potent

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6
Q

what transporter hormones do T3 and T4 bind to

A

Thyroxine binding globulin
thyroxine binding pre-albumin
albumin

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7
Q

where is most of the T4 converted to T3

A

The liver

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8
Q

what happens to free T3 and T4 and thyroid stimulating hormone in primary hypothyroidism

A

Low T3 and T4

High TSH to try and increase the thyroid hormone levels

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9
Q

what happens to free T3 and T4 and TSH in primary hyperthyroidism

A

Free T3/4 is high

TSH drops to try and stop the thyroid gland producing too much thyroxine

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10
Q

what happens to T3/4 and TSH in secondary hypothyroidism

A

reduces TSH production (due to something in the pituitary or hypothalamus not working)

subsequently also had low T3/T4

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11
Q

what happens to T3/4 and TSH in secondary hyperthyroidism

A

vvv rare - due to a problem in pituitary gland where TSH is secreted too much and doesn’t respond to negative feedback (could be from a rare tumour)

TSH is high so free T4/T3 is high

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12
Q

what does hypothyroidism describe

A

any disorder resulting in insufficient secretion of thyroid hormones

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13
Q

what does myxoedema describe

A

severe hypothyroidism and is a medical emergency (severe under active)

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14
Q

what does pretibial myxoedema describe

A

Rare clinical sign of grave’s disease which results from hyperthyroidism

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15
Q

what populations have higher incidence of hypothyroidism

A

white populations
women
older

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16
Q

what causes goitrous primary hypothyroidism

A 
chronic thyroiditis (Hashimoto's thyroiditis) 
iodine deficiency 
Drug induces 
maternally transmitted (mum on anti-thyroid drugs when pregnant) 
Hereditary biosynthetic defects
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17
Q

what causes non-goitrous primary hypothyroidism

A

atrophic thyroiditis
positive-ablative therapy (radio iodine, surgery)
post-radiotherapy
congenital defect

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18
Q

what causes SECONDARY hypothyroidism

A 
disease of the pituitary and hypothalamus 
glands 
-infiltrative 
-infectious 
-malignant 
-traumatic
-congenital 
-cranial radiotherapy 
-drug-induced
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19
Q

what is autoimmune hypothyridism

A

autoimmune conditions which attack the hypothalamus and pituitary

most common cause in western world

often family history

antibodies against thyroid peroxidase (TPO)

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20
Q

what are the 3 stages in the progression of hypothyroidism

A

euthyroid

mild thyroid failure

overt hypothyroidism

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21
Q

what are some clinical features of hypothyroidism

A

hair and skin

  • coarse, sparse hair
  • dull expressionless face
  • periorbital puffiness
  • pale cool skin that feels doughy to touch
  • vitiligo may be present
  • hypercarotenaemia

cold intolerance

pitting oedema

reduced heart rate
cardiac dilation
pericardial effusion
worsening of heart failure

hyperlipidaemia

decreased appetite
weight gain

constipation

deep house voice
macroglossia
obstructive sleep apnoea

decreases intellectual and motor activities 
muscle stiffness, cramps 
peripheral neuropathy 
prolongation of tendon jerks 
carpal tunnel

heavier periods

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22
Q

What are the lab investigations seen in hypothyroidism

A

Increased TSH
Decreased free T4/3

increases macrocytosis
increases creatine kinase
increases LDL-cholesterol
hypoantaemia (decreases renal water loss)
hyperprolactinaemia (increased TRH increases PRL)

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23
Q

what are they thyroid autoantibodies

A

anti-TPO antibody (autoimmune hypothyroidism)
anti-thyroglobulin antibody
TSH receptor antibody (graves)

24
Q

how is hypothyroidism managed

A

normal metabolic rate should be restored gradually - may lead to cardiac arrhythmia

younger patients - start levothyroxine at 50-100micrograms daily

start elderly patients on levothyroxine 25-50 micrograms daily adjusted evert 4 weeks according to response

check TSH 2 months after any dose change

once stabilised check TSH every 12-18 months

25
Q

what is levothyroxine

A

T4

26
Q

How do you treat secondary hypothyroidism

A

TSH unreliable

titrate does of levothyroxine to the free t4 level

27
Q

when is levothyroxine taken

A

preferably before breakfast

28
Q

what happens to dose requirements in pregnancy

A

25-50% increase in dose of levothyroxine

29
Q

what is myxoedema coma

A

typically affects older women with a long standing unrecognised/untreated hypothyroidism

morality up to 60%

bradycardia, type 2 respect failure and co-existing adrenal failure

30
Q

how to treat myoxeoedema coma

A 
intensive care 
passively rewarm 
cardiac monitoring for arrythmia 
close monitoring of urine output 
broad spec antibiotics 
causes thyroxine
31
Q

what is thyrotoxicosis

A

state arriving when tissues are exposed to too much thyroid hormone

32
Q

what is hyperthyroidism

A

specifically conditions in which overactivity of the thyroid gland leads to thyrotoxicosis

33
Q

symptoms and signs of thyrotoxicosis

A

Cardiac
palpitation, atrial fibrillation
cardiac failure (v rare)

Sympathetic
tremor, sweating

CNS
anxiety, nervousness, irritability, sleep disturbance

GI
frequent, loose bowel movement

vision
lid retraction
double vision
proptosis (graves)

hair and skin
brittle, thin hair
rapid fingernail growth

reproductive
menstrual cycle changes (lighter, less frequent)

muscles
weakness especially in thighs and upper arms

Metabolism
weight loss and increases appetite

Thermogenesis
intolerance to heat

34
Q

what are come hyperthyroid causes of thyrotoxicosis

A

hyperthyroidism

excessive thyroid stimulation

  • Graves
  • hashitoxicosis
  • thyrotropinoma
  • thyroid cancer
  • choriocarcinoma

thyroid nodules with autonomous function

  • toxic solitary nodule
  • toxic multi nodular goitre
35
Q

What are some causes of thyrotoxicosis which aren’t associated with hyperthyroidism

A

Thyroid inflammation

  • subacute thyroiditis
  • post-partum thyroiditis
  • drug induced

exogenous thyroid hormones

  • over treatment with levothyroxine
  • thyrotoxicosis facitia

ectopic thyroid tissue

  • metastatic carcinoma
  • stuma ovarii
36
Q

Who gets graves disease

A

younger 20-50 years
more common in females
smoking is important -harder to treat, increases risk of eye disease
combination of genetic susceptibility and environmental factors

37
Q

investigations in Graves disease

A 
Decreases TSH (often 0) 
high free T3/4

increased alkaline phos and hypercalcaemia

decreased white cell count

TSH receptor antibody (TRAb)
-no need to image thyroid gland if this is found - can confidently make diagnosis

38
Q

What is pretibial myxoedema

A

bumpy red rash on lower limbs
only seen in graves disease
v rare

39
Q

what is thyroid acropachy

A

severe nail clubbing seen in graves

v v rare

40
Q

what is a thyroid bruit

A

sign of graves disease (only)
associated with large goitres
reflective of a hyper vascular thyroid
escalate over the thyroid

41
Q

What is Grave’s eye disease

A 
occurs in 20% of graves patients 
TRAb driven pathophysiology 
can be unilateral 
most is mild and treated with eye drops
 more severe can require use of steroids, radiotherapy or surgery
42
Q

What is nodular thyroid disease and who gets it

A

seen in older patients
insidious onset
thyroid feels nodular
asymmetrical goitre

43
Q

what tests do you do for nodular thyroid disease

A 
increased Free T4/3
decreased TSH 
antibody NEGATIVE (TRAb) 
Scintigraphy (thyroid uptake scan)- high uptake 
thyroid ultrasound
44
Q

what is thyroid storm/crisis

A

severe clinical presentation of an overactive thyroid/thyrotoxicosis

occurs in people with underlying graves disease who are exposed to a ‘second hit’ eg. infection, surgery

45
Q

Treatment for hyperthyroidism

A

anti-thyroid drugs (ATDS)

46
Q

first line drug for hyperthyroidism

A

Carbimaxole
once daily
lower rate of side effects compared to PTU
risk of aplasia cutis in early pregnancy

47
Q

What is the 1st line drug for hyperthroidism in the first trimester of pregnant

A

Propylthiouracil (PTU)
twice daily
10x less potent

48
Q

side effects of antithyroid drugs

A

generally well tolerated
1-5% will develop allergic type reactions - rash, urticaria, arthralgia
cholestatic jaundice, increased liver enzymes, hepatic failure
Agranulocytosis (rare, happens in first 6 weeks)

49
Q

what drug can you give to help the symptoms of hyperthyroidism

A

b-blockers
propranolol is the drug of choice
use in caution with those in asthma - CCB can be used instead

50
Q

what is radio iodine treatment

A

1st choice treatment for relapsed graves disease and nodular thyroid disease

safe, no increased risk of thyroid cancer

51
Q

when is thyroidectomy done

A

when radio iodine is contraindicated

52
Q

what effect does amiodarone have on the thyroid

A

can cause hypo or hyper thyroids

53
Q

what is subclinical hypothyroidism

A

increased TSH but with normal free T3/4

54
Q

what is subclinical hyperthyroidism

A

Decreased TSH

normal free T3/4

55
Q

what is such euthyroid syndrome

A

encountered in the unwell, hospitalised patients

impact of intercurrent illness on the hypothalamus??

2 ENDOCRINE (32 decks)

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