Clinical Thyroid Disease Flashcards
what are the types of thyroid disease?
- Hypothyroidism
- Goitre
- Thyroid Cancer
- Hyperthyroidism
how does the feedback system form the thyroid gland work?
symptoms of hyperthyroid and hypothyroid are ___________
opposing
what are the symptoms of hypothyroid?
- 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 symptoms of hyperthyroid?
- Weight Loss
- Anxiety/Irritability
- Heat Intolerance
- Bowel frequency
- Light periods
- Sweaty palms
- Palipitations
- Hyperreflexia/Tremors
- Goitre
- Thyroid eye symptoms/signs
how does primary (thyroid) hypothyroidism affect TSF, T4 and T3 levels?
Raised TSH, Low FT4 & FT3
how does subclinical (compensated) hypothyroidism affect TSF, T4 and T3 levels?
Raised TSH: Normal FT4 & FT3
Subclinical – the pituitary has produced enough TSH to make enough T3 and T4
Subclinical hypothyroidism is an early, mild form of hypothyroidism, a condition in which the body doesn’t produce enough thyroid hormones. It’s called subclinical because only the serum level of thyroid stimulating hormone from the front of the pituitary gland is a little bit above normal
how does secondary (pituitary) hypothyroidism affect TSF, T4 and T3 levels?
Low TSH, Low FT4 & FT3
what is the prevelance of hypothyroidism?
- Commonest endocrine condition after diabetes
- 1.9% in women
- O.1% in men
- Subclinical hypothyroidism 5%
- 10% of women over the age of 60
what are the different categories that the causes of primary hypothyroidism can come under?
congenital
acquired
what are the congenital causes of primary hypothyroidism?
Developmental:
agenesis (refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue)/maldevelopment (faulty or imperfect development)
Dyshormonogenesis:
trapping/organification
Incidence of congenital hypothyroidism 1 in 3500 births - All babies screened in the UK - if not picked up early then growth retardation
what are aquired causes of primary hypothyroidsm?
Autoimmune thyroid disease (commonest) - Hashimotos/atrophic
Iatrogenic:
- postoperative/post-radioactive iodine
- External RT for head and neck cancers
- antithyroid drugs, Amiodarone, Lithium, Interferon
Chronic iodine deficiency
Post-subacute thyroiditis - Post partum thyroiditis
What are the causes of secondary/tertiary hypothyroidism?
Pituitary/hypothalamic damage:
- pituitary tumour eg tumour
- craniopharyngioma (tumour that begins near the pituitary gland)
- post pituitary surgery or radiotherapy
Describe Thyroid Hormone Secretion in hypothyroidism
what investigations can be done for hypothyroidism?
- TSH/fT4
- Autoantibodies: TPO (Thyroid peroxidase antibodies)
(FBC (MCV increased))
(Lipids (hypercholesterolaemia))
(Hyponatremia due to SIADH)
(Increased muscle enzymes, ALT, CK)
(hyperprolactinaemia)
what is the treatment of hypothyroidism?
Levothyroxine (T4) tablets
(Liothyronine (T3)) - not as good as T4 tablets
Combination of T4 & T3: no benefit in studies
Initial dose Levothyroxine 1.6mcg/kg for adults <65 years old
Titrate in 25mcg steps according to TFT
Half-life of T4 is 7 days
After stabilisation annual testing of TSH
Compliance is important
how does replacement of thyroxine after many weeks affect levels of TSH and T4?
need to wait around 6-8 weeks to see true benefits of treatment
name a feature of hypothyroidism seen on this man
baggy eyes
What is the treatment of hypothyroidism (special situations):
Ischaemic Heart disease & Adults >65 years
Start at lower dose 25mcg and increase cautiously; risk of precipitating angina
People with ischemic needs a slower starts as the medication causes a faster heart
What is the treatment of hypothyroidism (special situations):
Postpartum thyroiditis
Trial withdrawal and measure TFT’s in 6 weeks
What is the treatment of hypothyroidism (special situations):
Myxedema coma
(severe hypothyroidism leading to decreased mental status, hypothermia, and other symptoms related to slowing of function in multiple organs. It is a medical emergency with a high mortality rate)
Very rare emergency, may need IV T3 (steroid)
how do you treat subclinical hypothyroidism?
Repeat tests after 2-3 months with TPO antibodies
Consider treatment TSH >10
TSH >5 with symptoms:
- Trial of therapy for 6 months and continue if symptomatic improvement
- If not stop and annual monitoring if TPO+ or every 2 to 3 years
what may the risk of over treatment in subclincal hypothyroidism cause?
osteopenia and atrial fibrillation
(Osteopenia is when your bones are weaker than normal but not so far gone that they break easily)
how does the treatment of hypothyroidism change during pregnancy?
Increased Levothyroxine requirements during pregnancy
Optimise preconceptually
what may inadequatley treated hypothyroidism during pregnancy cause?
Inadequately treated hypothyroidism linked with increased foetal loss and Lower IQ
what should be done in a perosn with hypothyroidism when they find out they are pregnant?
Increase LT4 dose by about 25% and monitor closely
Aim to keep TSH in low normal range (<2.5mU/l) and FT4 in high normal range
Treat _________ hypothyroidism if planning pregnancy (or pregnant)
subclinical
what is goitre?
a swelling of the neck resulting from enlargement of the thyroid gland
what are the causes of goitre?
Physiological: Puberty, Pregnancy
Autoimmune: Graves’ disease, Hashimoto’s disease
Thyroiditis: Acute (de Quervain’s ), Chronic fibrotic (Reidel’s)
Iodine deficiency (endemic goitre)
Dyshormogenesis
Goitrogens
(Goitrogens are substances that disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. This triggers the pituitary to release thyroid-stimulating hormone (TSH), which then promotes the growth of thyroid tissue, eventually leading to goitre)
what are the different types of goitre?
- Multinodular Goitre
- Diffuse goitre: Colloid, Simple
- Cysts
- Tumours: Adenomas, Carcinoma, Lymphoma
- Miscellaneous: Sarcoidosis, Tuberculosis
what increases the risk of malignancy in a solitary nodule thyroid
Child
Adults less than 30 or over 60 years
Previous head and neck irradiation
Pain, cervical lymphadenopathy
Do large dominant nodule of MNG also need investigation?
YES
5% chance of malignancy