Thyroid Flashcards
What are the developmental abnormalities of thyroid development?
- Wrong place: ectopic thyroid
2. Wrong connection: thyroglossal duct
What happens when TSH stimulates the thyroid?
- Iodine taken up by follicular cell
- T4 and T3 synthesized by follicular cell (done on thyroglobulin, stored in colloid)
- T4 (and thyroglobulin) released into circulation
What are the types of differentiated thyroid cancer?
- Papillary**
2. Follicular thyroid cancer
How can we stage thyroid cancer?
MACIS staging system is good for dynamic staging
TNM good for static staging
What kind of thyroid nodules are there?
Cold nodules- don’t take up tracer but may be malignant
Hot nodules- do take up tracer due to hyperthyroid mutation pattern. 98% benign
What features are suspicious for thyroid malignancy?
Rapid growth Hard nodules Fixed Hoarseness Lymphadenopathy
Extremes of age
Large module
Compression SX
Where does follicular cancer metastasize to?
Lung and bone
If someone has a low TSH with a palpable nodule, what we do next?
Radio nuclear thyroid test, this will tell us if this is a hot nodule
What do we do for palpable nodules with high or normal TSH?
Do ultrasound- look for cancerous features like microcalcification, irregular borders, tall nodules, hypoechoic
What does thyroid suppression therapy do in the elderly?
May increase risk of osteoporosis and a fib
How do we monitor cancer recurrence?
Thyroglobulin levels
What is the marker of medullary thyroid cancer?
Calcitonin from c cell
What are the symptoms of hypothyroidism?
Weight gain Cold intolerance Fatigue, lethargy, depression Dry hair, coarse/puffy skin, possible goitre Menstrual irregularities Slow reflex relaxation* Muscle weakness, bradycardia,
What are the clinical features of Graves’ disease?
Weight loss despite appetite Tremor Heat intolerance and sweating Palpations, shortness of breath, a fib Amenorrhea Diarrhea Hair loss Muscle weakness and fatigue Graves orbitopathy Pre tibial myxedema
Proptosis
Forward protrusion of the orbit due to graves
What features are common between pregnancy and hyperthyroid?
Heat intolerance Tachycardia Wide pulse pressure Flow murmur Radiant hands and feet Glitter (in I deficient areas)
How do thyroid bio markers change over pregnancy?
- Initial decrease in TSH because of HCG
- Free T4 decreases in second and third trimesters
- Bound T3/4 increase as increase in thyroid binding globulin
What is the main cause of hyperthyroid in pregnancy?
Graves’ disease
What are the risks of untreated hyperthyroid in pregnancy?
Miscarriage
Preterm delivery
Low birth weight
Pre eclampsia
What are the risks of untreated HYPO thyroid?
Fetal loss Hypertension Placental abruption Postpartum hemorrhage Impaired neurodevelopmen to
What do we use to treat post partum thyroiditis?
Hyper: beta blockers
Hypo: consider thyroxine replacement
What causes transient hypothyroidism in the infant?
- Prematurity
- Maternal anti-thyroid drugs
- Maternal TSH blocking antibody
What causes persistent hypothyroidism in the infant?
- Thyroid dysgenesis** (75%)
- Dyshormonogenesis
- Central hypothyroidism
- Maternal radio-iodine ablation (super duper stupid)
How do we treat graves disease in pregnancy?
- Cannot radioablate- contraindicated in preg/breastfeed
- PTU anti-thyroid drug- best as crosses placenta least
- May abate slightly due to effect of pregnancy
Who is at risk of post partum thyroiditis?
- Those wtih DM1
2. Hashimoto’s thyroiditis already
What characterizes hashimoto’s thyroiditis?
lymphocytic infiltration of the thyroid, causing progressive thyroid tissue destruction
Toxic adenoma
Least common cause of hyperthyroid
Low TSH, high t3/4
Palpable nodule with focal point of uptake on scan
Multinodular goitre
Low TSH, high t3/t4
Nodules with radio iodine uptake
May have SX of thyroid enlargement
Graves Disease
Most common cause of hyperthyroid Caused by autoimmune attack on thyroid Presentation: -occulopathy -clubbing -pretibial myxedema -bruit over goiter -firm, non tender goiter
Radioiodine scan shows diffuse uptake
Thyroiditis
Thyroid releases preformed thyroxine, leading to hyper then hypo thyroid
Presentation
- painful thyroid (post viral)
- may be post partum or drug induced (amiodarone)
Scan shows no uptake of radio iodine.
What is the most common cause of hypothyroid?
Hashimoto’s
Myxedema coma
Rare, life threatening, hypothyroid state
Tx with IV thyroxine
what antibodies do you have in Hashimotos?
Anti thyroid peroxidase
What information do we get from an uptake study?
Quantitative- just get a number. Good for ruling in or out Thyroiditis and graves.
Not good for nodules
What does a scan tell you?
Gives you a picture- good for differentiating toxic adenoma vs multinodular goiter
Painful thyroid enlargement
Thyroiditis (subacute/ granulomatous) is painful- radiates into jaw and ears
Post partum is not painful
What are the serious side effects of methimazole
Agranulocytosis
Hepatitis
Fetal abnormalities
What effect does prematurity have on thyroid?
Will be hypothyroid because fetal t4s need a bit of time to catch up
Causes of congenital hypothyroid?
Sick euthyroid
Maternal anti thyroid drugs
Maternal TSH blocking ab
Thyroid dysgenesis*
