Download Thyroid

Thyroid (easy peasy!)
Dr Lucie Spooner- F1
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Anatomy- zzzzz
HPA Axis
Hypothyroidism
Thyrotoxicosis
Carbimazole- what you need to know
Surgical complications
Thyroid and pregnancy
Cases x4.
Pituitary Gland- just learn these.
Anterior:
FSH
LH
Prolactin
GH
ACTH
TSH
Posterior:
ADH
Oxytocin
Definitions
• Hypothyroidism:
– clinic state from decreased production of
and/or effect of thyroid hormones
• Hyperthyroidism:
– clinical state of increased circulation of free
thyroid hormones. Excessive Thyroxine (T3 or
T4 or both).
Hypothyroidism- clinical features
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Weight gain
Cold intolerance
Hair loss and Dry skin
Bradycardia
– Pericardial effusion
– Premature IHD
• Constipation
• Menstrual Disturbances
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– Menorrhagia (Anaemia)
– Amenorrhoea (Rare)
Mentally Slow
– Depression
– Psychosis
– Cerebellar disturbances
Facial puffiness
Bilateral Carpal Tunnel Syndrome
Slow relaxing reflexes
Hair loss
Hypothyroidism- Causes
Caused by thyroid (primary) the pituitary
(secondary) or the hypothalamus (tertiary).
PRIMARY: Autoimmune
- There are 3 main examples- what are they?
Primary: Acquired
- There are 3 main causes- what are they?
Primary Autoimmune
1. Hashimoto's thyroiditis:
- autoimmune, very common, familial.
- Autoantibody to thyroglobulin and thyroid= goitre.
- Family members may have Addison's, pernicious anaemia or
diabetes.
- It is 10 times more common in women
- anti-thyroid peroxidase and also anti-Tg antibodies
2. Atrophic hypothyroidism:
- autoimmune, elderly, autoantibody to TSH receptor.
- No goitre.
3. Congenital Hypothyroidism:
-should be picked up in first 4 weeks or high risk of mental
retardation- screened neonatally.
Primary- Acquired:
1. Iodine deficiency (Endemic goitre).
2. Iodine excess (Amiodarone).
3. Post treatment for Hyperthyroidism.
– Surgery
– Radioiodine
– Antithyroid Drugs (such as???)
Hypothyroidism- Causes
Secondary
• Pituitary failure= Low levels of TSH
• Very rare- just mention it.
Hypothyroid- Investigations
Investigations:
How are they split up?
Bedside
Bloods
Radiology
Special Tests
Bedside1. ECG:
• a prolonged Q-T interval
• low P, T and QRS amplitude
• atrioventricular and intraventricular conduction disturbances e.g.
right bundle branch block
• 2. BM
Bloods
• FBC shows macroscopic anaemia (MCV 95-110).
- If Hb <100 suspect an additional cause. Can
have pernicious anaemia (MCV>115) or iron
deficiency anaemia from menorrhagia
• TFT: Low T4 and high TSH- primary.
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Low or normal TSH- secondary or tertiary.
• Cortisol: exclude Addison's
• Thyroid antibodies
Investigations• Who would you screen ?
– Perimenopausal women and those with non
specific symptoms
– Confusion
– T1DM (especially those attempting to
conceive)
Management
• Conservative: lifestyle- weight loss, exercise (only
subclinical!)
– If subclinical- check antibodies- if negative and
asymtpomatic- screen annually.
– 2% chance of clinical signs annually.
• Medical:
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50ug/day and increasing to 125-150ug/day.
Half an hour before food or won’t be absorbed.
Check free thyroxine at 6-8 week intervals
If patient remains symptomatic- what would you do?
• Surgical: see surgical lecture!
Myxoedema Coma:
Rare complication with 50% mortality rate.
Suspect in any patient with hypothermia
or coma. Start IV T3 (20ug bolus
repeated every 6 hours). As thyroid failure
may relate to pituitary disease (if Na is
low), give hydrocortisone too until an
accurate diagnosis is made.
Hyperthyroidism- Symptoms
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Weight loss
Increased appetite
Irritability/restlessness
Palpitations
Heat intolerance
Diarrhoea
Oligomenorrhoea
Hyperthyroidism- clinical signs
• Tremor
• Eye complaints (Grave’s)
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Proptosis
Dry eye
Difficulty looking up
Lid lag
Opthalmoplegia
• Pretibial Myxoedema and acropachy (Grave’s)
• Atrial Fibrillation
Pretibial myxoedema
• Anterior aspect
lower legs
• Indurated
discoluration of
the skin.
What do you see?
Thyroid Eye Disease
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Occurs in Grave’s disease
Exopthalalmus
Proptosis
Opthalmoplegia
May be unilateral
May present for the first time after treatment
More common in smokers
Rarely resolves completely.
Causes: deposition of lymphocytes and oedema.
• Risk of optic nerve compression- can cause blindness, so
Rx with steroids and surgery when ‘malignant
exopthalmus’
Thyrotoxicosis (give me 4 causes)
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Grave’s disease
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75% cases
Thyroid-stimulating immunoglobulins (TSIs).
• Thyroglobulin.
• Thyroid peroxidase
• Sodium-iodide symporter.
• TSH receptor.
Goitre, eye signs and Pretibial Myxoedema
Toxic multi nodular goitre
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15%
– Older women
– Likely remission after medical therapy.
Toxic nodule/adenoma
– 5%,
– Likely remission after medical therapy
De Quervains thyroiditis
– Transient from acute inflammatory viral process
– Accompanied fever, malaise and pain in neck
Amiodarone induced Thyrotoxicosis
Postpartum thyroiditis
Iatrogenic - too much thyroxine
Hashimotos’s thyroiditis- .... Before you go hypo
Investigations
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Bedside:
ECG, Urine dip, BM
Bloods:
Serum TSH < 0.05mU/L
Raised free T4 or T3 confirms diagnosis
Thyroid antibodies
Radiology:
USS if lump/nodule
Special tests:
Radioisotope iodine scanning (hot or cold
nodule)
FNA for cytology (more relevant if cancer
suspected)
Thyrotoxic storm – medical
emergency
• Rapid deterioration of hyperthyroidism with
10% mortality
• Severe tachycardia, restlessness,
hyperpyrexia, cardiac failure
• Precipitated by stress, infection or surgery in
the unprepared patient
• High dose BB and start carbimzole or
propylthiouracil immediately and give iodide
and hour later and IV steroids to inhibit new
thyroid hormone production.
Management
• Conservative:
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Lubricant eye drops such as methylcellulose
Stop smoking
Tape eye lids to ensure closure at night
Systemic steroids 30-120mg OD to reduce inflammation if severe
• Medical:
– Beta Blockers – alleviated symptoms such as tremor and
palpitations, normally the first Rx initiated.
– Antithyroid drugs:
• Carbimazole - inhibit formation of thyroid hormone
• Propythiouracil - safe in pregnancy
– Radioactive iodine
• Contraindicated in pregnancy
• Patients must be euthyroid before treatment
• Can lead to hypothyroidism
• Surgical:
– Thyroidectomy
Carbimazole
• Grave’s:
– Use for 18-24 months and then trial without
medication
• Side effects:
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Most common: Urticrial rash (2-4%)
Most serious: Agranulocytosis (1/300-500)
Arthralgia
Headache
Alopecia.
Normally develop within 4 weeks of
treatment.
– If fever or sore throat- stop medication
immediately.
• Most patients feel better after 10 -14 days.
• Takes 4-6 weeks before euthyroid.
Complications after
thyroidectomy
• Immediate:
– Haemorrhage
– Recurrent larangeal nerve palsy
• Intermediate:
– Infection
• Long-term:
– Hypothyroidism
– Hypoparathyroidism
Pregnancy and thyrotoxicosis
• Hyperthyroidism in pregnancy
• HCG is a weak stimulator of TSH receptor
• Very important to treat
• Untreated leads to miscarriage, premature
labour, low birth weight and eclampsia.
• Radioiodine is absolutely contraindicated.
Thyroid Function Test.
• First line is ONLY TSH . Lab will not check T3/T4
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unless the TSH is deranged.
T4 normal range is 12-20.
TSH normal range is 0.6-6.0
Hypothyroidism:
– Primary- TSH is > 6. Secondary- TSH is low to normal.
– T4/T3 low.
• Hyperthyroidism
– TSH is <0.05
– T3/T4 raised as a result of negative feedback (high T4 and
low TSH can also be found in Exac of COPD, RA and HF,
raised T3 however is always thyrotoxicosis)
Case 1
39 year old lady presents with 3 months history of
weight loss and diarrhoea. On further questioning you
find out that she has been suffering from excessive
sweating and a recent family holiday to Tunisia was
ruined as she was unable to tolerate the weather. Her
eyes also feel gritty a lot of the time and she has had
friends ask her why she is staring at them. She is
otherwise well and her only medication is St John’s
Wort. She has no known allergies. She does not
smoke and drinks alcohol socially. On exam she is
slight with sweaty palms and a fine tremor when her
arms are out stretched. Her pulse is 100bpm and
irregularly irregular. She has exophthalmos and lid lag.
She also has a diffuse non tender swelling on the front
of her neck which moves with swallowing.
• What are your differentials for this lady?
(make sure these include all important
differentials that must be ruled out)
• How would you investigate her?
• How would you manage her?
• What are the cardinal features of Grave’s
disease?
• What drug is used in pregnant
hyperthyroid patients?
• What are complications of thyroid surgery?
Case 2
• T4 is 12.
• TSH is 7
• Subclinical
• ?would you treat?
• Only if symptomatic or trying to conceivemust check for autoantibodies.
Case 3
• Pt admitted with fast AF
• TSH is undetectable
• T4 of 36
• What would you do?
• Measure T3 in this case as could be secondary
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to heart failure. T3 is always raised in
thyrotoxicis.
If elevated T3 – start antithyroid medication.
Case 4
• 45 yo lady with palpitations, weight loss.
• TSH undetectable
• T4 is 40
• Which Rx would help control her
symptoms fastest?
• Beta Blocker... Then antithyroid
medication.
Key Points
1. Remember to ask about red flag
symptoms.
2. With a thyroid case they may hide the
glass of water- look for it.
3. Don’t forget to treat symptoms as well as
the disease- e.g. Beta blockers.
4. Talk slowly and breath... They want to
pass you. I promise.
5. Practise, practise and practise....
Any Questions?