Thyroid gland clinical Flashcards
(57 cards)
Symptoms/signs of hypothyroidism (11) - think metabolism is lowered
Weight Gain Lethargy Cold intolerance Constipation Mental slowness Depression Myalgia/ muscle weakness Dry Skin/Hair Bradycardia Slow reflexes GOITRE
Severe hypothyroidism
-puffy face, large tongue, hoarse voice
Symptoms/signs of hyperthyroidism (14) - think metabolism is increased
Weight loss Anxiety/irritability Heat intolerance Bowel frequency increase - diarrhoea Frequent urination Light periods Sweating Hair loss/thinning Palpitations Hyper-reflexia/tremors GOITRE Red/dry eyes Osteoporosis
State the common tests of thyroid function and their interpretation, and the methods available for thyroid imaging.
TSH
FT4
FT3
Describe the levels of TSH, FT4 and FT3 in
- primary hypothyroidism
- subclinical (compensated) hypothyroidism)
- secondary hypothyroidism
Raised TSH, Low FT4 & FT3
Raised TSH, Normal FT4 & FT3
Low (or normal) TSH, Low FT4 & FT3
How is congenital hypothyroidism identified/screened for
screened for after birth in heel prick test
Management of hypothyroidism in the newborn
Levothyroxine
Causes of primary hypothyroidism
- congenital causes (2)
- acquired causes (4)
Congenital
- maldevelopment
- dyshormonogenesis
Acquired
- hashimoto’s thyroiditis/disease (autoimmune thyroiditis)
- iatrogenic - from radioactive iodine, radiotherapy
- chronic iodine deficiency
- post partum thyroiditis
Hashimoto’s thyroiditis aka
Chronic immune/lymphocytic thyroiditis
Most common cause of primary hypothyroidism
Hashimoto’s disease (Autoimmune thyroiditis)
Causes of central (i.e. pituitary or hypothalamus) hypothyroidism
- neoplastic (2)
- infiltrative (1)
- traumatic (3)
- iatrogenic (2)
neoplastic
- pituitary tumour (prevents TSH production)
- hypothalamus trauma or tumour
infiltrative
-infection, e.g. TB, syphilis
traumatic
- head trauma
- pituitary apoplexy
- sheehan’s syndrome (pituitary necrosis due to blood loss and hypovolemic shock post birth)
iatrogenic
- pituitary surgery
- pituitary radiotherapy
Signs of a pituitary mass causing hypothyroidism
Papilloedema
Bitemporal hemianopia
Biochemical investigations of primary hypothyroidism (e.g. Hashimoto’s thyroiditis) + typical findings of these (5)
hint: 2 autoantibodies
serum TSH - high
free serum T4 (FT4) - low
Autoantibodies
- thyroid peroxidase (TPO) antibodies - elevated
- anti-thyroglobulin antibodies - elevated
serum cholesterol - high
Treatment of primary hypothyroidism
Lifelong once daily levothyroxine (T4)
-initially 50 micrograms/day then adjust dose in increments of 12.5 to 25 micrograms to normalise TSH
Pathogenesis of Hashimoto’s disease (5)
Autoimmune destruction of thyroid involving thyroid peroxidase antibodies attacking the gland
- lymphocytic infiltrate into the gland
- destruction of thyroid follicles
- apoptosis of thyroid epithelial cells
- extensive fibrosis
- Hurthle cell change
Special situations where treatment of hypothyroidism (referring to dose of levothyroxine) differs to usual
IHD
-start at lower dose and increase cautiously as can precipitate angina
Pregnancy
-need increased dose as increased demand for thyroid hormone in foetus
Myxedema (aka SEVERE HYPOTHYRDOIDISM) coma
-may need IV T3
What is myxoedema + what do you get it in
aka SEVERE HYPOTHYRDOIDISM
- deposits of chains of sugar molecules (complex mucopolysaccharides) in the skin cause myxoedema
- these compounds attract water, which lead to swelling
-swelling of face and esp lower legs
get it in hypo and hyperthyroidism (esp graves)
Levothyroxine doesn’t usually have side effects but over-treatment can lead to what side effect
Hyperthyroidism symptoms - sweating, chest pain, weight loss, palpitations
Why is there the need to increase dose of levothyroxine during pregnancy
as extra thyroid hormone needed for foetal nervous development
Causes of a goitre (6)
Physiological
- puberty
- pregnancy
Autoimmune thyroiditis
- grave’s disease
- hashimoto’s disease
Non-autoimmune thyroiditis
Iodine deficiency
Dyshormogenesis
Goitrogens
Types of goitres (5)
Multinodular goitre
Diffuse goitre (colloid or simple)
Cysts
Tumours (adenoma or carcinoma or lymphoma)
Miscellaneous causes (sarcoidosis, TB)
A solitary thyroid nodule has risk of what
malignancy
Investigations of a solitary thyroid nodule/ potential thyroid cancer (5)
TFTs - TSH, fT4
Ultrasound - differentiates benign v malignant
Fine needle aspiration (FNA) biopsy
Laryngoscopy - if vocal cords paralysed, suggests malignancy
Isotope thyroid scan - to look for hot/cold nodule
Nodules detected on a thyroid scan can be hot or cold
-what’s the difference
Thyroid scan involves giving radioactive iodine to see if there’s any region that’s over-producing or under-producing thyroid hormone
Hot nodule - a nodular region of the thyroid gland that takes up large amounts of radioactive iodine relative to the rest of the thyroid gland so it’s producing too much hormone and shows up darker
Cold nodule - nodule is composed of cells that do not make thyroid hormone (don’t absorb iodine) (i.e. non functioning nodule) so appears as defect/hole in the scan
Do cold or hot solitary thyroid nodules have high risk of malignancy
Cold
