Clinical thyroid disease Flashcards Preview

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Flashcards in Clinical thyroid disease Deck (28):
1

What will happen if hypothyroidism is severe?

- FBC (MCV (mean corpuscular volume) increased)
- Lipids (hypercholesterolaemia)
- Hyponatraemia (low sodium) due to SIADH (high secretion of antidiuretic hormone)
- Increased muscle enzymes (ALT and CK)
- Hyperprolactinaemia

2

What are the common tests for hypothyroidism?

○ TSH/ fT4
○ Autoantibodies: TPO (Thyroid peroxidase antibodies)

3

What are the common tests for hyperthyroidism?

- Thyroid peroxidase antibodies
- TSH receptor antibodies
- Review personal/ family history for concurrent autoimmune disease

4

What are the common presentations of hypothyroidism?

○ Weight gain
○ Lethargy
○ Heavy periods
○ Feeling cold
○ Dry skin/ hair
○ Slow reflexes
○ Constipation
○ Bradycardia
○ Goitre
○ Severe
- Puffy face
- Large tongue
- Hoarseness
- Coma

5

What are the common presentations of hyperthyroidism?

- Weight loss
- Sensitive to heat
- Light periods
- Anxiety/ irritability
- More bowel movements
- Palpitations
- Sweaty palms
- Hyperreflexia/ tremor
- Thyroid eye symptoms/ signs
- Goitre

6

What are the common presentations for grave's disease

- Thyroid eye disease (10%)
- Gynecomastia
- Thyroid acropathy
- Goitre
- Grave's demopathy

7

What are the different types of hypothyroidism?

○ Primary (thyroid)
○ Secondary (pituitary)
○ Subclinical (compensated)
○ Acquired
○ Pituitary/ hypothalamic damage

8

What are the different types of hyperthyroidism

○ Primary
○ Secondary
○ Thyrotoxicosis without hyperthyroidism
○ Subclinical hyperthyroidism

9

What are the general hyperthyroid management strategies?

○ Surgery
○ Antithyroid drugs
○ Radioiodine
○ Beta blockers
- Symptom management

10

Explain antithyroid drugs in more detail

- Drugs
□ Carbimazole
□ Propylthiouracil
- Side effects
□ Rash
□ Agranulocytosis 1:500
- Administration
□ Titration regime
® start at a high dose and then decrease the dose when stable
® 50% cure
® 30% hypothyroidism
□ Blockage
® Start at a high dose and then add in thyroxine when stable
® 50% cure
® 30% hypothyroidism
® Higher side effects
- Selected cases for long term low dose administration
□ Elderly
□ Cardiac complications
□ Unwilling for radioiodine

11

Explain radioiodine in more detail

- Types
□ High ablative dose
® 90% cure
® 70% hypothyroidism
□ Variable calculated
® 60-90% cure
® Less hypothyroidism
- Side effects
□ Cannot have contact with children or pregnant women for 4 weeks
□ It could cause eye problems (steroids)
□ For a month or two security alarms at the airport will go off

12

Discuss the principles of treatment of hypothyroidism

• Levothyroxine (T4) tablets
• Liothyronine (T3) doesn't really work and a combination of T3 and T4 doesn't work either
• Initial dose of levothyroxine is 50mcg/ day increase after 2 weeks to 100mcg
• Alter dose until TSH is normal (or fT4 is in normal range in secondary)
• After stabilisation there should be annual testing of TSH
• Compliance
• Ischemic heart disease
○ Start at lower dose 25mcg
○ Increase cautiously
○ Risk of precipitating angina
• Pregnancy
○ Most patients need an increase (35-40%) in LT4 dose
○ If they have subclinical hypothyroidism treat
○ Inadequate treatment of hypothyroidism linked with increased foetal loss and lower IQ
○ At diagnosis of pregnancy
- Increase LT4 dose by about 25% and monitor closely
- Aim to keep TSH in low normal range and FT4 in high normal range
• Postpartum thyroiditis
○ Trial withdrawal
○ Measure TFTs in 6 weeks
• Myxoedema coma
○ Very rare emergency
○ May need IV T3 (steroid)
• Subclinical hypothyroidism
○ Consider treating TSH >10
○ TSH >5 with positive thyroid antibodies
○ TSH elevated with symptoms: trial therapy of 3-4 months and continue if symptomatic improvement
○ Risk of overtreatment
- Osteopenia
- Atrial fibrillation

13

What are the types of thyroid cancer

• Papillary
• Follicular
• Anaplastic
• Lymphoma
• Medullary

14

How is thyroid cancer managed?

○ Prognosis poorer
- Age <16 or >45
- Tumour size
- Spread outside thyroid capsule and metastases
- TNM stage
○ Near total thyroidectomy
○ High dose radioiodine (ablative)
○ Long term suppression doses of thyroxine
○ Follow up
- Thyroglobulin
- Whole body iodine scanning (following 2-4 weeks of thyroxine withdrawal)

15

What happens in primary hypothyroidism?

- Raised TSH (thyroid secreting hormone)
- Low FT4 and FT3 (free thyroid 3 and 4)

16

What happens in secondary hypothyroidism?

- Low TSH
- Low FT4 and FT3

17

What happens in subclinical hypothyroidism?

- Raised TSH
- Normal FT4 and FT3

18

Explain acquired hypothyroidism

- Autoimmune thyroid disease (this is the most common in the UK)
□ Hashimotos
□ Atrophic
- Iatrogenic
□ Postoperative/ post radioactive iodine
□ External RT for head and neck cancers
□ Antithyroid drugs, Amiodarone, Lithium, Interferon
- Chronic iodine deficiency (commonest worldwide)
- Post subacute thyroiditis
□ Postpartum thyroiditis

19

What sort of pituitary/ hypothalamic damage causes hypothyroidism?

- Pituitary tumour
- Craniopharyngioma
- Post pituitary surgery or radiotherapy
- Sheehan's syndrome (where a woman has a massive postpartum haemorrhage)
- Isolated TRH deficiency

20

Describe primary hyperthyroidism

- Grave's disease
□ 70-80% of hyperthyroidism
□ Thyroid antibodies (TSH receptor antibodies)
- Toxic multinodular goitre
□ Most common cause of thyrotoxicosis in the elderly
□ Characteristic goitre and absence of grave's disease
□ Will not go into spontaneous remission
- Toxic adenoma

21

What causes secondary hyperthyroidism?

Pituitary adenoma secreting TSH (quite rare)

22

Explain thyrotoxicosis without hyperthyroidism

- Destructive thyroiditis (postpartum, subacute, amiodarone induced)
□ Subacute
® Generally younger patients <50 years
® Viral trigger (e.g. enterovirus, coxsackie)
® Often painful goitre +/- fever/ myalgia; ESR increased
® May require short term steroids and NSAIDs
- Excessive thyroxine administration

23

Explain subclinical hyperthyroidism

- TSH suppressed
- Normal free thyroid hormones
- Concerns
□ Bone: decreased bone density in postmenopausal; no clear fracture data
□ AF: 3 fold increased risk in over 60
- Treatment: consider ATD or RAI if persistent especially in the elderly or those with increased cardiac risk

24

Explain papillary thyroid cancer

○ Commonest
○ Multifocal, local spread to lymph nodes
○ Good prognosis

25

Explain follicular thyroid cancer

○ Usually a single lesion
○ Metastasis to lung and bone
○ Good prognosis if resectable

26

Explain anaplastic thyroid cancer

○ <5% of thyroid cancers
○ Aggressive, locally invasive
○ Very poor prognosis, do not respond to radioiodine
○ External RT may help briefly

27

Explain thyroid lymphoma

○ Rare; may arise from pre-existing Hashimoto's thyroiditis
○ External RT more helpful, combined with chemotherapy

28

Explain medullary thyroid cancer

○ Tumour arises from parafollicular C cells
○ Often associated with MEN 2
- Pheochromocytoma
- Hyperparathyroidism
○ Serum calcitonin levels raised
○ Treatment: total thyroidectomy, no role for radioiodine
○ Prognosis variable