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Yr 2 Endocrine > Thyroid Disorders > Flashcards

Flashcards in Thyroid Disorders Deck (38):
1

`How does hypothyroidism present?

- Weight Gain
- Cold intolerance
- Brittle nails, thin/dry skin & hair
- Hyporeflexia, slow speech
- Lethargy & low mood
- Constipation
- Bradycardia
- Heavy periods

Severe cases can cause puffy face, large tongue, hoarseness and coma

2

How does hyperthyroidism present?

- Weight loss
- Heat intolerance
- Muscle weakness
- Hyperreflexia
- Frequent bowel movements
- Palpitations
- Light periods
- Sweaty palms
- Thyroid eye symptoms (bulging)
- Anxiety/irritibility

3

How does gender affect thyroid disease?

Both hyper and hypothyroidism are much more common in women

4

What are the types of Hypothyroidism?

Primary
Subclinical
Secondary

5

What causes congenital Hypothyroidism?

- developmental problems e.g. agenesis
- Dyshormogenensis (autosomal recessive condition preventing TH production)

6

What causes acquired Primary Hypothyroidism?

- Autoimmune (hashimoto's) thyroiditis
- Iatrogenic
- Chronic Iodine Deficiency
- Post-subacute thyroiditis

7

What can cause secondary or tertiary hypothyroidism?

- Pituitary tumours
- Craniopharyngioma
- Pituitary surgery/radiotherapy
- Sheehan's Syndrome
- Isolated TRH deficiency

8

What is Sheehan's Syndrome?

Post-partum ischaemic necrosis of the pituitary due to blood loss/hypovolaemic shock of childbirth

Its a potential cause of secondary hypothyroidism

9

List some iatrogenic causes of primary hypothyroidism?

Post op
Radioactive Iodine or Anti-Thyroids
Amiodarone (Sub-acute thyroiditis)
RT for H/N cancer

10

What tests would you run for suspected hypothyroidism?

- TFTs i.e. TSH & fT4
- Thyroid Peroxidase Antibodies

- FBC
- Lipids
- Serum Na+
- Muscle enzymes, ALT & CK
- Prolactin

11

Explain why youd do each test for hypothyroidism?

FBC - Raised MCV (RBC size)
Lipids - Hypercholesterolaemia
Na+ - Hyponatremia due to excess ADH from hypothyroidism
Muscle enzymes, ALT & CK are all raised
Prolactin - Hyperprolactinaemia

12

How will TFT's Appear for each class of Hypothyridism?

Primary - Low fT4 but high TSH
Secondary - Low fT4 & low or normal TSH
Subclinical - Normal fT4 & High TSH

13

What do we use to manage hypothyroidism?

Levothyroxine (T4) tablets

14

Explain the dosing of Levothyroxine?

Start at 50mcg/day
Titrate up to 100mcg/day after 2 weeks
Keep increasing until their TSH (primary disease) or fT4 (Secondary Disease) is normal.

15

What special cases affect how you use Levothyroxine?

- IHD needs to be started lower and titrated slowly as it can trigger Angina
- Pregnant women need more T4
- Myxedema Coma needs IV T3
- Post-partum Thyroiditis needs to have the meds removed for 6 weeks and TFTs measured to see when it abates

16

Should we treat subclinical hypothyroidism?

Only if:
- TSH >10
- >5 + Antibodies
- TSH elevated + symptoms (temporary trial therapy for symptom improvement)
- Pregnant or planning pregnancy

17

What are the risks of levothyroxine?

- Thyrotoxicosis
- AF
- Osteopenia

18

How does Goitre occur in hypothyroidism?

No fT4
No -ve feedback
Excess TSH
Hyperstimulation -> Hyperplasia of Thyroid gland

19

What are the causes for PRimary hyperthyroidism?

Graves Disease - 70%
Toxic Multinodular Goitre - 20%
Thyroid Adenoma
Subacute Thyroiditis

20

What is Grave's Disease?

Autoimmune condition in which TSH receptor antibodies continuously stimulate the thyroid causing PRimary hyperthyroidism

21

What is Toxic Multinodular goitre?

Multinodular Goitre producing excess thyroid hormones

22

Whats the main cause of secondary hyperthyroidism?

Pituitary Adenoma producing TSH

23

What is Thyrotoxicosis without hyperthyroidism?

Where you get excess thyroid hormone without hyperthyroidism.

Due to exogenous thyroxine or destructive thyroiditis causing stores of thyroid hormones to be released

24

What causes destructive thyroiditis?

Post-partum
Amiodarone induced

Most common causes

25

How do you diagnose Hyperthyroidism?

Based on the presentation and TFTs

Can do TSH receptor antibody test for Grave's Specifically

26

Describe how hyperthyroidism TFTs appear?

Primary - High fT4 & low TSH

Secondary - High fT4 & High TSH

Subclinical - Normal fT4 & low TSH

27

How is Hyperthyroidism treated?

1st) Anti-thyroid Drugs (ATDs)

2nd) Radioiodine

Resection of thyroid or pituitary adenoma

28

How are anti-thyroid drugs used?

Carbimazole or Propylthiourcil

A titration regimen for 12-18 months then move on to radioiodine if uncured

29

How is Radioiodine used?

For hyperthyroidism

USed after ATDs fail

High dose ablative regimen cures 90% of patients but leaves 70% hypothyroid

30

When would we treat Subclinical hyperthyroidism?

If:
- Elderly
- Persistant subclinical hyperthyroidism
- High cardiac risk patient

31

Risks of Hyperthyroidism treatments?

ATDs can cause a rash and agranulocytosis which is a rare and potentially fatal complication

Radioiodine makes ~70% of patients hypothyroid and can cause eye disease

32

What are the types of hyperparathyroidism?

Primary - sporadic or familial (MEN-1)

Secondary - Physiological response to low Ca2+ resorption due to kidney failure

Almost all primarys are due to adenomas, some hyperplasia and rarely carcinoma

33

How would you investigate a goitre?

- TFTs
- Isotope scabn
- US
- FNA
- CXR for retrosternal extension

IF you suspect cancer a serum calcitonin to rule out MEdullary Thyroid Cancer

34

What are the main types of thyroid cancer?

Vast bulk are differentiated Thyroid Carcinomas, either papillary or follicular.

Also Anaplastic, Lymphoma and medullary thyroid cancer.

35

How do Differentiated Thyroid Carcinomas spread?

Papillary carcinomas spread to local lymph nodes

Follicular Carcinomas metastasise to lung/blood/bone

36

What is medullary thyroid cancer?

Cancer of C cells in the thyroid gland
Produces calcitonin
Associated with MEN 2

37

Treatments for Thyroid cancers?

High Dose radioiodine
Long-Term levothyroxine to suppress the tumour

Lymphoma - External RT/chemo

Anaplastic - Can be delayed with external RT

Thyroidectomy - Only treatment that works on medullary thyroid cancer

38

When would we stop Levothyroxine for Thyroid cancer?

Withdraw from the thyroxine for 2 weeks as a trial and do a full body radioisotope scan to see if its all gone