Lec8 - Thyroid Disease Flashcards
What is hypothyroidism?
An underproduction of thyroid hormone
What are the two main types of hypothyroidism?
Primary hypothyroidism
Secondary hypothyroidism
What is Primary hypothyroidism?
A problem with the thyroid gland itself
What is Secondary hypothyroidism?
A problem with the hypothalamus or pituitary leading to the thyroid gland being unable to function properly
What is hyPERthyroidism?
An overproduction of thyroid hormone
What else is hyperthyroidism known as?
Thyrotoxicosis
What is goitre?
An enlargement of the thyroid gland
What does euthyroid mean?
Normal production of thyroid hormone
Where is the thyroid gland?
Low in the neck, feel for the thyroid cartilage/ Adam’s apple and then inferior and laterally
What is a good sign of hyperthyroidism?
A bruit
What is a bruit?
A sound that is heard when the blood passing the thyroid is in some way obstructed
What is retrosternal extension/ goitre?
When the thyroid has moved down inferiorly from where it should be and now lies atop of the sternum
How can you tell if there is retrosternal extension?
If you can feel under the thyroid gland OR
if you percuss the sternum and get a dull sound
What do you check in thyroid function tests (TFTs)?
Levels of: TSH T3 T4 Thyroid autoantibodies e.g. thyroid peroxidase auto-antibody (anti TPO AB) TSH receptor autoantibody (TRAB)
What is the best biomarker of thyroid status?
TSH
How else can you assess thyroid function?
By looking at a graph of density (y axis) against the TSH microlitreU/ml)
What do you look for in the curve?
The shape of the area under the curve - if there is a tail from 3 onwards
If there is a tail in the curve from 3 onwards, what does this mean?
There there is an increased frequency of thyroid autoantibodies
What is the significance of the presence of autoantibodies
Likely to indicate autoimmune disease
If there is a negative autoAB result what does this mean?
It does not necessarily exclude autoimmune disease - they could still have an autoimmune disease
The presence of autoAB makes it easier to confirm the diagnosis
Name the two types of thyroid autoAB:
Destructive autoAB
Stimulatory autoAB
What do destructive autoABs do?
They target the thyroid for autoimmune destruction and therefore cause hypothyroidism
What do stimulatory autoABs do?
They stimulate the TSH receptor and cause an overproduction of thyroid hormone
What are the symptoms of HYPOTHYROIDISM?
Lethargy Mild weight gain Cold intolerance Constipation Facial puffiness Dry skin Hair loss Hoarseness Heavy menstrual periods
What are the symptoms of severe HYPOTHYROIDISM?
Change in appearance e.g. of the face Puffy and Pale Periorbital Oedema Bradycardia Carpal tunnel i.e. signs of median nerve compression Croaky voice Diffuse hair loss Dry flaking skin Effusions e.g. ascites, pericardial Goitre
Rarely: Coma/stupor
Causes of primary hypothyroidism
Autoimmune hypothyroidism Congenital hypothyroidism Drugs e.g. lithium & amiodarone Iatrogenic - after treatment for hyperthyroidism Iodine deficiency (not in the UK) Thyroiditis
What is the typical thyroid status of someone with primary hypothyroidism (thyroid dysfunction)?
HIGH TSH, Low T3, T4
What is the typical thyroid status of someone with secondary hypothyroidism?
LOW TSH, Low T3, T4
What investigations would you do for someone who came in with symptoms matching hypothyroidism?
Thyroid TFTs - TSH T3 and T4
Could also check thyroid autoantibodies
No imaging necessary
What would be the treatment for primary hypothyroidism?
Thyroxine T4
Normal dose = 100-150micrograms a day
(depending on body weight and if they are elderly or have IHD then start with 25mcg daily with increments 4-6 weekly
Aim for normal FT4 without TSH suppression
Why don’t you administer both T3 and T4?
Because T4 is converted to T3 in the target tissues anyway and there is no evidence to suggest that combination therapy works
Name the types of AUTOIMMUNE HYPOTHYROIDISM
Chronic autoimmune thyroiditis/ Hashimoto’s disease
Myxoedema
What is Hashimoto’s disease or chronic autoimmune thyroiditis?
Autoimmune disease causing hypothyroidism
with a goitre
with lymphocytic infiltration
What is a myxoedema?
accumulation of glycosaminoglycans in the interstitial spaces of tissues causing very severe hypothyroidism (any cause) and coma
What are the symptoms of thyrotoxicosis/hyperthyroidism?
Anxiety/ irritability Heat intolerance Increased sweating Increased appetite Lack of energy Loose bowels Oligomenorrhoea Palpitations driven into arrhythmia Pruritus Thirst Weight loss with increased appetite Weight gain
What are the signs of thyrotoxicosis?
Atrial fibrillation Brisk reflexes Eye signs Muscle weakness Tachycardia Tremor Thyroid bruit Warm, moist skin
What is Thyroid Eye Disease (TED)?
Inflammation of all the tissues surrounding the eye except the eye itself e.g. fat, conjunctiva, muscles, eyelids
What is another name for TED?
Thyroid Associated Ophthalmopathy (TAO)
What is TED/TAO associated with?
Autoimmune hyperthyroidism e.g. Grave’s disease
20% puts with Grave’s have TED but not always at the same time or even at all
What is an increased risk of TED?
Smoking
What are the ‘mild’ symptoms of TED?
Dry or itchy eyes - artificial tears help
Prominent eyes/ change in appearance
What are the worrisome symptoms of TED?
Diplopia/ loss of sight loss of colour vision - grey or blurred patches Redness/ swelling of conjunctiva Unable to close eyes fully Ache/ pain/ tightness in or behind eye
What is one way of confirming TED?
T2 weight MRI with STIR sequencing shows the inflammatory activity of the extra ocular muscles
What are the hand signs associated with thyrotoxicosis?
Fine tremor
Warm/ sweaty hands
What are the pulse signs of thyrotoxicosis?
Sinus tachycardia
Atrial fibrillation
What are the neck signs of thyrotoxicosis?
Goitre
Movement when swelling
Smooth/ not
Bruit/ not
Eye signs of thyrotoxicosis
Eyelid retraction/ lag
Proptosis/ exopthalmos
Opthalmoplegia - abnormal eye movements causing diplopia
Inflammation of the conjunctiva
What is autoimmune hyperthyroidism also known as?
Grave’s disease
What is the pathophysiology of Grave’s disease?
The autoantibodies stimulate the TSH receptor causing overproduction of the thyroid hormone and thyroid growth (goitre)
How common is Grave’s?
Accounts for 75% of cases
Who does it often effect?
Women between 30-50
What are the other causes of thyrotoxicosis?
Toxic multinodular goitre
Toxic adenoma - single cancerous nodule
Thyroiditis
Drugs e.g. amiodarone
Gestational thyrotoxicosis
Placental human chorionic gonadotrophin hormone is structurally similar to TSH and has TSH-like action on the thyroid
Increased if hyperemesis/twin pregnancy
Usually settles after 1st trimester of pregnancy
What are the helpful diagnostic features of Grave’s disease?
Personal/ FHx of Grave’s disease
Goitre with a bruit
Thyroid eye disease (20% Grave’s disease)
Positive thyroid autoantibody titre
When is Grave’s more common and more likely?
If the pt also has another autoimmune disease
What type of imaging can you do?
Thyroid uptake scan (uptake scan)
Functional scan: darker areas of increased activity
What are the types of treatment options for Grave’s disease?
Medical Radioiodine (radiation therapy) Surgery Symptom control - Beta blockers e.g. propanolol No treatment
What is the medical treatment for Grave’s
Carbimazole or propylthiouracil (PTU)
18 months to 2 year
Titrate or block replace
What is a rare side effect of carbimazole and propylthiouracil?
Agranulocytosis
What is the long term cure rate with medical treatment of Grave’s?
1/3
What is the relapse rate with medical treatment of Grave’s?
2/3 - usually within the first year
What is radio iodine treatment?
Oral treatment with radio iodine concentrated in the thyroid
The radiation kills the thyroid cells
What do you have to ensure before radio iodine therapy?
That the pt is euthyroid with medical therapy
What are the precautions that need to be taken?
Pt need to are not to try for children for 6 months if women 4 months if man
Not to be given if pregnant or breast feeding
Not to be given if there is severe thyroid eye disease
Warn pt about airplane security systems
Need to avoid close contact with others for 1-2 weeks post treatment - tricky with young kids
What is the risk of radio iodine treatment?
40% chance of permanent hypothyroidism after treatment
What is the surgery treatment for Grave’s?
Thyroidectomy - almost total
What must be ensured before pts have thyroidectomy?
That they are euthyroid from medical treatment first
What is the risk of surgery
The neck scar Anaesthetic Hypoparathyroidism Hypothyroidism Vocal cord palsy - from recurrent laryngeal nerve damage
What is the treatment for a toxic adenoma or toxic multi nodular goitre?
Short term medical therapy
Subsequent curative therapy e.g. radioiodine
What must patients know about treatments for thyroid?
They do not help eye disease
What are the TED treatment options?
Active
Burnt out
What are the active TED treatment options?
Encourage smoking cessation
Steroids - IV methylpred or oral prednisolone
Other immunosuppressive/ steroid sparing agents
Radiotherapy
What are the burnt out TED treatment options
Surgery
Orbital decompression
Eyelid surgery
What are the risks of surgery for TED?
May be left with disfigurement leading to impaired quality of life and social avoidance
What is a thyroid storm?
A thyrotoxicosis crisis
Who usually gets it?
Usually people with secondary Grave’s
Why do people get it?
If their hyperthryoidism is unrecognised and untreated or incompletely treated
What triggers a thyroid storm?
Surgery - GA
Childbirth
Acute severe illness e.g. infection, DKA, trauma, stroke, PE
What does a thyroid storm involve?
Multi system Hyperpyrexia CNS - delirium/ agitation CArdiovascular - tachycardia, atrial dysrhythmias, ventricular dysfunction, heart failure GI - nausea and vomiting
What can a thyroid storm result in?
Because the degree of elevation of thyroid hormone concentration does not distinguish uncomplicated thyrotoxicosis from thyroid storm
High mortality rate
ITU level care
What is the risk of not treating thyrotoxicosis?
Symptoms worsening
Atrial fibrillation
Stroke
Osteoporosis - Fractures
What is thyroiditis
Usually self limiting thyroid disease
What is transient mild thyrotoxicosis?
Always resolves in 1-2months
Beta blockers if required
Anti thyroid drugs won’t work but if lasts 4-6 months may require thyroxine treatment
Associations of autoimmune disease with other diseases:
Other autoimmune endocrine disease e.g. Type 1 diabetes Pernicious anaemia Coeliac disease Premature ovarian failure Addison's disease
Syndromes
Turner syndrome
Downs syndrome
What medications are associated with thyroid disease?
Hypothyroidism:
Lithium - inhibits thyroid hormone synthesis and secretion
Hypothyroidism and hyperthyroidism:
Amiodarone
