T1 L8: Thyroid disease Flashcards
What is a Goitre?
An enlarged thyroid gland
What does Euthyroid mean?
Normal production of thyroid hormones
What is a bruit?
An extreme amount of blood flow
You listen for it during a thyroid examination
What hormones do thyroid function tests look at?
TSH, FT4, FT3, and thyroid autoantibodies like anti-TPO AB and TRAB
Which hormone is the best biomarker of thyroid status?
TSH
How long does it take for TSH to respond to change?
About 6 weeks
What do thyroid autoantibodies indicate?
They’re not pathogenic but indicate risk of autoimmune disease
Negative autoantibodies don’t exclude autoimmune disease but a positive result confirms disease
What are the 2 types of thyroid autoantibodies?
Destructive - target thyroid for autoimmune destruction
Stimulatory - stimulates TSH receptor (TRAB)
What are some symptoms of hypothyroidism?
Lethargy Mild weight gain Cold intolerance Constipation Facial puffiness Dry skin Hair loss Hoarseness Heavy menstrual periods
What are some symptoms of severe hypothyroidism?
Change is appearance Eg. puffiness or pale skin 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
What is a myxoedema coma?
Patients exhibit multiple organ abnormalities and progressive mental deterioration
What are some causes of primary hypothyroidism?
- Autoimmune hypothyroidism
- Iatrogenic
- Thyroiditis
- Drugs like lithium or amiodarone which contains lots of iodine
- Congenital
- Iodine deficiency
What are the levels of TSH, T4, and T3 in primary hypothyroidism?
High TSH, low T3 and T4
What are the levels of TSH, T4, and T3 in secondary hypothyroidism?
All are low
What causes secondary hypothyroidism?
Diseases of the hypothalamus or the pituitary
What investigations are done to confirm primary hypothyroidism?
Blood results but thyroid autoantibodies could also be checked. No imaging is needed
What is the treatment for hypothyroidism?
Start by giving thyroxine (T4) but give a smaller dose to those >65 or those with ischaemic heart disease
What is Hashimoto’s disease?
A chronic autoimmune thyroiditis
What is Myxoedema?
An accumulation of glycosaminoglycans in the interstitial spaces of tissues
Is hyperthyroidism the same as thyrotoxicosis?
Yes
What are some symptoms of hyperthyroidosis?
Weight loss Lack of energy Heat intolerance Anxiety/irritability Increased appetite Increased sweating Thirst Palpitations Pruritus Weight gain Loose bowels Oligomenorrhoea
What is Pruritus?
Itchy skin
What is Oligomenorrhoea?
Sparse periods
What are some signs of Thyrotoxicosis?
Tremor Warm, moist skin Tachycardia Wye signs Thyroid bruit Muscle weakness Atrial fibrillation Brisk reflexes
What are some symptoms of thyroid eye disease (TED), thyroid associated ophthalmopathy (TAO)?
Itchy, dry eyes Prominent eyes/ change in their appearance Diplopia Loss of sight Loss of colour vision Redness/ swelling conjunctiva Unable to fully close eyes Ache, pain, tightness in or behind the eye
What is proptosis?
Pushing forward of the eyes
What are some signs of thyrotoxicosis?
Hand tremor Sinus tachycardia Atrial fibrillation Goitre Lid retraction Proptosis Ophthalmoplegia Inflammation of the conjunctiva
What is Grave’s disease?
An autoimmune hyperthyroidism
What are some causes of thyrotoxicsosis?
Grave's disease Toxic multinodular goitre Toxic adenoma Thyroiditis Drugs
What is toxic adenoma?
A single nodule benign swelling
What is a toxic thyroid?
One that is producing too much thyroid hormone
What is Gestational thyrotoxicosis?
Occurs when the placental B-human chorionic gonadotrophin is structurally similar to TSH and TSH-like action on the thyroid
It’s more common in twin pregnancies and normally settles after the 1st trimester of pregnancy because then the levels of HCG go down
What are some helpful diagnostic features of Grave’s disease?
-Personal or family history of any autoimmune thyroid/ endocrine disease
-Goitre with a bruit
Thyroid eye disease (20% Grave’s)
Positive thyroid autoantibody titre
What are some investigations that can be done to prove hyperthyroidism?
- Thyroid function blood tests
- Thyroid autoantibody presence
- Thyroid uptake scan to show increased activity
How is Grave’s disease treated?
Radioiodine
Surgery
Symptoms control with Beta-blockers like Propranolol
What risks are there is Grave’s disease is left untreated?
Symptoms will worsen
Atrial fibrillation leading to stroke
Osteoporosis
Some people may refuse treatment because they are happy with the weight loss
What are some medical treatments for Grave’s disease?
Carbimazole or Propylthiouracil (PTU)
-For 18months-2 years
Rare complication: Agranulocytosis which can present as severe mouth ulcers
But 2/3 patients relapse (mostly men)
What is Agranulocytosis?
Extremely low number of granulocytes
How does radioiodine treatment work?
The radioiodine will be mostly taken up by the thyroid gland because it uses mostly of the iodine and this will kill the thyroid cells
40% risk of permanent hypothyroidism after treatment
People have to avoid contact with others for a prolonged period of time so not good for children
-Not to be used with pregnancy
What are some of the risks associated with surgery to treat hyperthyroidism?
Anaesthetic risks Neck scar Hypothyroidism Hypoparathyroidism Vocal chord Palsy (due to damage to the recurrent laryngeal nerve)
What is the treatment for thyroid eye disease?
- Smoking cessation
- Steroids
- Radiotherapy
- Surgical treatment (Eg. orbital decompression or eyelid surgery)
What is a Thyroid storm (Thyrotoxic crisis)?
It’s an acute excessive release of thyroid hormones
Usually secondary to Grave’s disease. It’s often triggered by surgery, childbirth, acute severe illness
What are some features of a thyroid storm?
- Multisystem
- Hyperpyrexia
- Cardiovascular issues like Tachycardia or heart failure
- GI issues like nausea, diarrhoea, hepatocellular dysfunction
High mortality rate or ICU-level care
What are some features of thyroditis?
- Transient mild thyrotoxicosis that always resolves after a couple of months
- Longer hypothyroid phase of 4-6 months
When should a diagnosis of thyroiditis be considered?
- Patient is pregnant/ within 1 year post-partum
- Patient has very tender thyroid as this is not seen with Grave’s disease or a Goitre
- Clinical thyroid status doesn’t fit the lab results
- No diagnostic feature of Grave’s disease
- Current/ recent treatment with immunomodulatory medication
What are some diseases associated with Thyroiditis?
Autoimmune endocrine conditions like T1 diabetes, Pernicious anaemia, Coeliac disease, Premature ovarian failure, Addison’s disease
Syndromes like Turner’s or Down’s
