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My Endocrinology > Hyperthyroidism > Flashcards

Hyperthyroidism Flashcards

1
Q

2 common causes

A

Grave’s disease (autoimmune)

Plummer’s disease (not autoimmune)

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2
Q

What happens in Grave’s disease

A

Antibodies bind to TSH receptor in thyroid

Makes thyroid overactive

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3
Q

Clinical features of hyperthyroidism

A 
Lid lag
Tachycardia
Palpitations
Weight loss and increased appetite
Sweating
Heat intolerance
Breathless
Diarrhoe
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4
Q

How to differentiate between Graves and other causes of hyperthyroidism

A 
Graves - antibodies bind to receptors behind eye, in soft tissue of shin etc.
Get:
exophthalmos
pretibial myxoedema
goitre (smooth enlarged thyroid)
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5
Q

Plummer’s disease is caused by

A

Toxic nodular goitre

Benign adenoma –> overactive –> makes thyroxine

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6
Q

Plummer’s disease CF

A

same as Grave’s –> losing weight, increased appetite, hot, tachycardia, palpitations, breathless etc
But
Lump is on one side (tumour only on one side of the thyroid)

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7
Q

What scan can you do

A

Technitium/iodine scan

Iodine scan will show the iodine going to the tumour
Plummer’s: there’s too much thyroxine from the tumour part of the thyroid gland–> pituitary stops making TSH–> normal part of gland stops making thyroxine and shrinks

On scan, Plummers: one hot nodule
Graves: large smooth thyroid gland

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8
Q

What is a rare but severe complication of hyperthyroidism

mortality if untreated. Die of..

A

thyroid storm

50%

Heart failure or arrhythmia

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9
Q

Clinical features of thyroid storm

A 
Hyperpyrexia (temp >41)
tachycardia/ arrhythmia
cardiac failure
delirium/ frank psychosis
hepatocellular dysfunction - jaundice
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10
Q

Treatment options for thyroid storm

A

Surgery - thyroidectomy
Radioiodine
Drugs

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11
Q

Cause/ what happens in viral thyroiditis

A

Virus attacks the thyroid so it stops making thyroxine and makes the virus itself. Causes fever
Damage the thyroid follicles so all the stored thyroxine is released.

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12
Q

Symptoms/ CF of viral thyroiditis

A

Painful dysphasia
Pyrexia
Hyperthyroidism
Raised ESR

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13
Q

Patient with viral thyroiditis presents with

A

hyperthyroidism - overactive thyroid - as all the stored thyroxine is released

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14
Q

If you do a technetium scan on a patient with viral thyroiditis what do you see and why

A

See no radioiodine uptake because the thyroid stopped making thyroxine

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15
Q

What happens a month after a patient has had viral thyroiditis
And a month after that?

A

They become hypothyroid as all the stored thyroxine is exhausted.
The cells are recovered and start producing thyroxine again - patient becomes euthyroid again

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16
Q

Treatment for hyperthyroidism

A

Drugs that decrease thyroid hormone synthesis (anti-thyroids)

  • Thionamides e.g. Propylthiouracil (PTU); Carbimazole (CBZ)
  • Potassium iodide
  • Radioiodine

Drugs that help with the symptoms
- beta blockers

17
Q

Thionamides can be used to treat

When it is used

A

Daily treatment of :
Graves
Plummers

When:
- used to control the hypothyroidism before thyroidectomy - don’t want to give general anaesthetic to someone who is tachycardia

  • Following radio iodine treatment - takes a while to work
18
Q

Thionamides mechanism of action

A

Inhibit thyroperoxidase —
therefore inhibit iodination of thyroglobulin and the coupling of iodotyrosines –> inhibiting T3/4 synthesis and secretion

may suppress antibody production (graves)
may decrease the conversion of T4–>T3 in peripheral tissues

19
Q

Why are the clinical effects of thionamides only seen weeks after they are taken, despite the biochemical effects occurring within hours?

A

There are a lot of stored thyroid hormone in the lumen of follicles.
They are not affected by thionamides (only newly synthesised thyroxine will be)

20
Q

Unwanted actions of thionamides

A 
Agranulocytosis (rare) - decreased neutrophils 
Rash (common)
Headaches
Nausea
Jaundice
Joint pain
21
Q

Pharmacokinetics of thionamides

A

Taken orally
Carbimazole is a pro-drug. converted to Methimazole

Metabolised in liver
Excreted in the urine

22
Q

Special consideration for thionamides

A

It can cross the placenta and is secreted into breast milk

High doses in pregnant women can cause foetal hypothyroidism

23
Q

Which of the two thionamides enter the breast milk less

A

Propylthiouracil less than carbimazole (PTU

24
Q

Role of beta blockers in thyrotoxicosis

A

Takes several weeks for anti-thyroid drugs to take effect
Deals with symptoms of thyrotoxicosis e.g. tremor, tachycardia, anxiety

Given non-selective beta blocker

25
Q

Iodide treatment given as
It is used in combination with other drugs for…

Has a maximal effect after … days of continuous administration

A

Potassium iodide given as Lugol’s solution/ aqueous iodine

preparation for surgery (reduces the size and vascularity of the thyroid)
severe thyrotoxicosis (thyroid storm)

10

26
Q

Potassium iodide MOA

A

Inhibits iodination of thyroglobulin

Inhibits generation of H202

27
Q

Unwanted actions of potassium iodide

A

Allergic reaction- rashes, fever, angioedema

28
Q

Radioiodine is used to treat

A

Graves
Plummers (toxic nodular disease)
Thyroid cancer

29
Q

Radioiodine MOA

A

Taken up by thyroid follicular cells and accumulates in the colloid.
From the colloid it emits beta particles of radiation that destroy the follicular cells

30
Q

Discontinue anti-thyroid drugs…day before starting radio iodine and why

A

7-10 days

so that the thyroid gland can start working again and be really active and take up a lot of radio iodine - maximal destruction of the gland

31
Q

Cautions of radioiodine

A

Avoid contact with small children for a few weeks

Don’t take it if pregnant or breast-feeding

32
Q

Technetium scan for the 3 causes of hyperthyroidism

A

Graves - entire thyroid gland active. Smooth and enlarged
Plummers - only one side active, rest is suppressed
Viral thyroiditis - no activity at all

My Endocrinology (8 decks)

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