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BSMS203 endocrinology (Theme 1) > 8. Thyroid disease: hyper, hypo and other > Flashcards

8. Thyroid disease: hyper, hypo and other Flashcards

1
Q

What is hypothyroidism?

A

Underproduction of thyroid hormone

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2
Q

Difference between primary and secondary hypothyroidism?

A

primary - due to a thyroid problem

secondary - due to a hypothalamic/pituitary problem

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3
Q

hyperthyroidism/thyrotoxicosis

A

overproduction of thyroid hormone

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4
Q

euthyroid

A

normal production of thyroid hormone

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5
Q

goitre

A

enlargement of thyroid gland

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6
Q

Patients with a goitre may be:

A

hyperthyroid
euthyroid (normal thyroid function)
hypothyroid

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7
Q

How do you examine the thyroid?

A

Low down in neck, feel for thyroid cartilage (Adam’s apple), then down & laterally
moves on swallowing
listen for bruit
Retrosternal extension: can you get below it? percuss over sternum. Check cervical LNS

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8
Q

What to consider when interpreting thyroid function tests?

A
  • remember the thyroid axis and negative feedback regulation
  • what isn’t working properly?
  • what is driving the system?
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9
Q

Normal ranges for thyroid hormones?

A 
TSH 0.3-4.2 mu/l
FT4  12-22 pmol/l
FT3 3.1-6.8 pmol/l
thyroid autoantibodies:
-anti TPO AB - thyroid peroxidase auto-antibody
-TRAB - TSH receptor autoantibody
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10
Q

TSH

A

best biomarker of thyroid status
Slow to respond to change - about 6 weeks
assumes normal pituitary function
remember negative feedback regulation

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11
Q

Thyroid autoantibodies

A

Prevalence of autoAB is much higher than autoimmune disease presence- marker of risk rather than causal
many autoAg are sequestered/intracellular
‘negative’ autoAB result doesn’t exclude autoimmune disease, but presence helps confirm diagnosis
different types of thyroid ABs:
-destructive - target thyroid for autoimmune destruction
-stimulatory - stimulate TSH receptor

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12
Q

Hypothyroidism symptoms

A 
May be none
Lethargy
Mild weight gain
Cold intolerance 
Constipation
Facial puffiness
Dry skin
Hair loss
Hoarseness
Heavy menstrual periods
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13
Q

Symptoms of SEVERE hypothyroidism

A 
Change in appearance eg face puffy and pale
Periorbital oedema
Dry flaking skin
Diffuse hair loss
Bradycardia
Signs of median nerve compression (carpal tunnel)
Effusions, eg ascites, pericardial
Delayed relaxation of reflexes
Croaky voice
Goitre
Rarely stupor or coma
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14
Q

Causes of primary hypothyroidism

A
  • Autoimmune hypothyroidism
  • Hypothyroidism after treatment for hyperthyroidism (iatrogenic)
  • Thyroiditis
  • Drugs (e.g. lithium, amiodarone)
  • Congenital hypothyroidism
  • Iodine deficiency (not UK)
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15
Q

Causes of secondary hypothyroidism

A

Diseases of hypothalamus or the pituitary gland

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16
Q

Hypothyroidism investigations

A

Look at FT4 first to see if hypo or hyper then TSH to see if primary or secondary
Blood results to confirm primary/secondary hypothyroidism
Could check thyroid autoantibodies
No imaging necessary

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17
Q

Hypothyroidism treatment

A

Start with thyroxine (T4) -100 mg daily
-Shorter symptomatic period
-Unless elderly / ischaemic heart disease
-> Start 25 mg daily with increments 4-6 weekly
Usual dose 100-150 mg daily -some variation with body weight
Aim normal FT4 without TSH suppression - Individual variation: may need fine tuning within reference ranges
No evidence in properly conducted trials to support T4/T3 combination therapy

18
Q

Symptoms of hyperthyroidism

A 
Weight loss
Lack of energy
Heat intolerance
Anxiety/irritability
Increased sweating
Increased appetite
Thirst
Palpitations
Pruritus
Weight gain
Loose bowels
Oligomenorrhoea (scarce periods)
19
Q

Signs of thyrotoxicosis

A 
Tremor
Warm, moist skin
Tachycardia
Brisk reflexes
Eye signs
Thyroid bruit
Muscle weakness
Atrial fibrillation
20
Q

Symptoms of thyroid eye disease (TED)/ thyroid associated opthalmopathy (TAO)

A
  • Associated with autoimmune hyperthyroidism (Graves disease) in ~ 20% of patients
  • Graves and TED may not occur at the same time, or at all
  • Increased risk in smokers
  • Autoantibody mediated
  • Inflammation of all orbital tissues except the eye
  • Fat, muscles, conjunctiva, eyelids
  • CT scan imaging helpful
21
Q

Mild symptoms of thyroid eye disease

A

itchy’ / dry eyes -Artificial tears help

‘prominent’ eyes / change in appearance

22
Q

worrisome symptoms of thyroid eye disease

A 
Diplopia / loss of sight
Loss of colour vision -Grey  / blurred patches
Redness / swelling of conjunctiva
Unable to close eyes fully
Ache / pain / tightness in or behind eye
23
Q

Signs associated with thyrotoxicosis

A 
Hands
- Fine tremor
- Warm
Pulse
-Sinus tachycardia
-Atrial fibrillation    
Neck
-Goitre
-Move when swallow
-Bruit / not
Eyes
-Lid retraction / lid lag
-Proptosis / exophthalmos
-Ophthalmoplegia
   -Abnormal eye movements, Causes diplopia
-Inflammation (conjunctiva)
24
Q

Causes of thyrotoxicosis

A 
Autoimmune (Graves)
Toxic multinodular goitre
toxin adenoma
thyroiditis
drugs e.g. amiodarone
25
Q

Graves disease

A

Autoantibody stimulates the TSH receptor, causing excess thyroid hormone production and thyroid growth (goitre)
Accounts for 75% of cases
• Typically women 30-50 yrs

26
Q

Gestational thyrotoxicosis

A

Placental β-human chorionic gonadotrophin is structurally similar to TSH and TSH-like action on the thyroid
­ likely if hyperemesis / twin pregnancy
Settles after 1st trimester of pregnancy

27
Q

Helpful diagnostic features of Graves disease

A

Likely Graves disease:
• Personal or family history of any autoimmune thyroid / endocrine disease
• Goitre with a bruit = Graves disease
• Thyroid eye disease = Graves disease (20%)
Positive thyroid autoantibody titre

28
Q

Further investigations for Graves disease

A 
Thyroid autoantibodies
May not need any imaging
	• clinical diagnosis may be clear
Thyroid uptake scan (isotope scan) 
	• Functional scan: darker areas of increased activity
29
Q

Graves disease treatment options

A 
• Medical
	• Radioiodine
	• Surgery
	• Symptom control
		○ Beta-blockers (propranolol), not if asthmatic
	• Risk of no treatment
		○ Symptoms worsening
		○ Atrial fibrillation e.g. stroke
		○ Osteoporosis e.g. fractures
30
Q

Medical therapy for hyperthyroidism

A 
Carbimazole or propylthiouracil (PTU)
18 months – 2 years
Titrate or block-replace
Rare side effect: agranulocytosis
Approx one third long term cure rate
Two thirds relapse
	• Usually first year
	• Cannot predict in advance
31
Q

Radioiodine therapy

A

RADIOACTIVE IODINE TREATMENT (I-131)
• Oral treatment, radioiodine concentrated in thyroid, radiation kills thyroid cells
• Medical therapy first till euthyroid
• Approx 40% risk permanent hypothyroidism after treatment
• Not if pregnant / breast feeding
• Need to avoid prolonged close contact with others for 1-2 weeks after treatment
○ Tricky if young children
• Not if severe thyroid eye disease
• Future pregnancies
○ Women advised to wait 6m, men 4m
• Warn patients about airplane security systems!

32
Q

Surgery for thyrotoxicosis

A

• Sub-total thyroidectomy (“almost total”)
• Patients must be euthyroid pre-operatively
○ Medical therapy first
• Risks
○ Anaesthetic
○ Neck scar
○ Hypothyroidism
○ Hypoparathyroidism
○ Vocal cord palsy (recurrent laryngeal nerve damage)

33
Q

Treatment for a toxic adenoma or toxic multinodular goitre

A

• Initial treatment: short term medical therapy (to control thyroid function tests)
Subsequent curative treatment: radioiodine

34
Q

Agreeing expectations

A

Reassurance that variety of Sx all relate to hyperthyroidism
• E.g. swings in emotion, anxiety, panic, irritability
May take time to feel ‘normal’ again
• Even after TFTs normalise, may be ‘lag’ phase of few months due to ‘metabolic rollercoaster’
Treatments for thyroid do not help eye disease
Risk of weight gain – watch dietary intake!
Confirm ‘family’ plans / intentions – guide treatment

35
Q

Thyroid eye disease treatment options

A

‘Active’
• Encourage smoking cessation
• Steroids
○ Pulsed IV methylpred / oral prednisolone
• Other immunosuppressive / steroid-sparing agents
• Radiotherapy
‘Burnt out’
• May be left with disfigurement causing impaired quality of life and social avoidance
• Surgical treatment
○ Orbital decompression
○ Eyelid surgery

36
Q

Thyroid storm

A 
Who gets it?
	• Usually 2º Graves
	• Unrecognised
	• Incompletely treated
		○ “start-stop”
		○ erratic compliance
		○ early on in course of treatment
		○ Surgery / radioiodine treatment without adequate preparation
	• RARE!
What triggers it?
	• Surgery (GA)
	• Childbirth
	• Acute severe illness
		○ Infection
		○ Trauma
		○ Diabetic ketoacidosis
		○ Stroke
		○ Pulmonary embolus
37
Q

Features of a thyroid storm

A 
• Multi-system
	• Graves
		○ Goitre, thyroid eye disease
	• Hyperpyrexia
	• CNS
		○ Agitation, delirium
	• Cardiovascular
		○ Tachycardia >140 bpm
		○ Atrial dysrhythmias
		○ Ventricular dysfunction
		○ Heart failure
	• GI
		○ Nausea & vomiting
		○ Diarrhoea
		○ Hepatocellular dysfunction
Degree of elevation of thyroid hormone concentrations does NOT distinguish uncomplicated thyrotoxicosis from thyroid storm
High mortality rate
ITU-level care
38
Q

Thyroiditis

A 
Usually self-limiting thyroid disease
Transient mild thyrotoxicosis
	• Always resolves (1-2 m)
	• b-blockers if required 
	• Isotope scan would be ‘cold’
	• Anti-thyroid drugs will not work    
Longer hypothyroid phase  (4-6 m)
	• 80% normal at 1 year
	• May require thyroxine treatment for a while
Annual TFTs: 30% hypothyroid @ 1 yr, 50% @ 3 yr
39
Q

When to consider thyroiditis?

A

Consider if:
Patient is pregnant / within 1 year post-partum
­ risk T1 diabetes, FHx thyroid disease, smoker
Patient has very tender thyroid
• May be raised inflammatory markers
Clinical thyroid status does not fit with lab results
• Rapidly changing thyroid function tests
No diagnostic features of Graves disease
Current / recent treatment with immunomodulatory medication

40
Q

Associations with thyroid disease

A 
Other autoimmune endocrine diseases
	• Type 1 diabetes
	• Pernicious anaemia
	• Coeliac disease
	• Premature ovarian failure
	• Addison’s disease
Syndromes
	• Turner syndrome
	• Down's syndrome
Medication for other diseases
	• Lithium 
		○ Inhibits thyroid hormone synthesis & secretion
	• Amiodorone
Annual thyroid functioning test screening recommended
41
Q

Goitre & thyroid nodules in euthyroid patients

A 
Euthyroid Goitre
	• Common
	• More common in iodine-deficient areas
	• May be multinodular
	• Usually nothing to worry about
Thyroid nodule
	• Thyroid nodule in euthyroid patient
	• Must exclude thyroid cancer - 5%
	• Ultrasound scan characteristics helpful
	• Fine needle aspiration biopsy for cytology

BSMS203 endocrinology (Theme 1) (26 decks)

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