Clinical Thyroid Disease Flashcards
Name as many symptoms of hypothyroidism as you can (10)
Weight gain Lethargy Feeling cold Constipation Heavy periods Dry skin/hair Bradycardia Slow reflexes Goitre Severe - puffy face, large tongue, hoarseness, coma
What are the 3 types of hypothyroidism and where are they based?
Primary - thyroid
Secondary - pituitary
Subclinical - compensated
What are the thyroid function test results in each type of hypothyroidism?
Primary: - Raised TSH; Low FT4 + FT3 Secondary: - Low TSH; Low FT4 + FT3 Subclinical: - Raised TSH; Normal FT4 + FT3
What is the most common type of hypothyroidism?
Primary (only 1-2% secondary)
What is subclinical hypothyroidism?
An early, mild form of hypothyroidism
Normal FT4 and FT3 as TSH has managed to compensate (even the TSH is only lil bit above normal)
Is hypothyroidism more prevalent in women or men?
Women (1.9% v 0.1% in men)
What percentage of the population have subclinical hypothyroidism? What percentage or women over 60 have it?
5%
10%
What is the prevalence of congenital hypothyroidism?
1 in 3500 births
What problems can arise in congenital primary hympothyroidism?
DEVELOPMENTAL - agenesis/maldevelopment
DYSHORMONOGENESIS - trapping/organification of iodide/dehalogenase deficiency (deiodinase enzyme)
(‘growth retardation and mental retardation’)
How do we screen for thyroid problems at birth?
Heel prick test
Give 4 general acquired causes of primary hypothyroidism
- Autoimmune thyroid disease
- Iatrogenic
- Chronic iodine deficiency
- Post-subacute thyroiditis
What are types of autoimmune thyroid disease?
Hashimotos
Atrophic
What are the iatrogenic causes of primary hypothyroidism?
- Post-op/post-radioactive iodine
- External RT for H+N cancer
- Antithyroid drugs, amiodarone, lithium, interferon
Give an example of post-subacute thyroiditis?
Post-partum thyroiditis
What is the major cause for secondary/tertiary hypothyroidism?
Pituitary/hypothalamic damage
Give 5 underlying causes for pituitary/tertiary hypothyroidism
- Pit tumour
- Craniopharyngioma
- Post pit surgery or radiotherapy
- Sheehan’s syndrome
- Isolated TRH deficiency
What is Sheehan’s syndrome?
Damage of pituitary gland during childbirth (due to low BP/haemhorrage during or post-partum)
Investigations for hypothyroidism?
TSH/fT4 (thyroid function tests)
Autoantibodies: TPO (thyroid peroxidase antibodies)
What is the standard treatment for hypothyroidism?
Levothyroxine (T4) tablets
What is the dosage plan for levothyroxine?
50mcg/day, increase after 2 weeks to 100mcg
For how long do u increase the dose of levothyroxine (T4)?
Until TSH is normal, or fT4 in normal range in secondary
How often should TSH be tested after stabilisation?
Annually
When should T4 be taken?
Same time everyday on empty stomach
Has there been any proven benefit to T3 treatment/T3 combined with T4?
No
In what patients should you be more careful with treatment?
IHD
Pregnancy
Postpartum thyroiditis
Myxedema coma
What should be done in patients with IHD?
Start at lower dose 25mcg and increase cautiously (risk of angina/HF)
What should be done in patients who r pregnant?
Most will need an increase in LT4 dose (25%)
What should be done in patients with post-partum thyroiditis?
Trial withdrawal and measure TFT’s in 6 wks
What should be done in patients with myxedema coma?
V rare emergency, may need IV T3 (steroid)
When should trial treatment for subclinical hypothyroidism be consdered?
TSH > 10
TSH > 5 w positive thyroid antibodies
TSH elevated with symptoms
Women pregnant/planning pregnancy