Thyroid Flashcards
What happens in the thyroid gland in response to TSH from the pituitary?
In response to TSH from the pituitary the thyroid:
- Takes up iodine into the follicular cell.
- Synthesizes T4 (and T3) within the follicular cell.
- Releases ready-made stored T4 (and T3) from the colloid of the follicle into the circulation.
Essentially the response is uptake, hormonogenesis and release.
If suspicious of hyper or hypothyroidism what is the first investigation that you order?
TSH
How can you differentiate Graves’ Disease from Thyroiditis?
PE: In Graves’ PE may reveal an occulopathy/exopthalmos, a bruit over the goiter and in rare cases pretibial myxoedema. In thyroiditis the gland is painful and the patient may have some viral/post-viral infectious symptoms.
Investigations: In Graves’ the anti-TSH receptor Ab will be positive and there will be a diffuse uptake of iodine on a scan. In Thyroiditis there will be no uptake as the thyroid gland is not working, doesn’t care about the iodine.
A 29 year old female presents for a prenatal appointment and on exam you note tachycardia, a wide pulse pressure, a flow murmur as well as radiant hands. She also complains of heat intolerance. Her TSH was measured at 10 weeks and was found to be low. What is your diagnosis?
These are all normal PE findings in a pregnant woman. The diagnosis is pregnancy. Don’t be tricked into thinking she is hyperthyroid! TSH is low (below non-pregnant TSH reference ranges) in 20% of pregnant women from 8-14 weeks. The free T3 and T4 should be normal.
What are the risks of hypothyroidism in pregnancy?
Risks of untreated overt hypothyroidism in pregnancy include fetal loss, HTN, placental abruption, postpartum hemmorhage and impaired neurodevelopment of the child.
In post-partum thyroiditis is the thyroid painful or non-painful?
Post-partum thyroiditis gland: Non-painful, non-tender, slightly enlarged and firm.
What are the main features of hyperthyroidism on presentation?
Hyperthyroidism presentation: warm hands/heat intolerance, palmar erythema, tremor, proximal muscle weakness, palpitations, wide pulse pressure, irritability, brisk reflexes, goiter, increased appetite, weight loss
What is the Graves’ triad?
Graves’ triad: occulopathy (eyelid retraction), clubbing, pretibial myxoedema. The patient may also have a bruit over the goiter as well as exophthalmos.
What is the first line anti-thyroid drug?
Methimazole: takes 18 months (on average) to induce remission
Which of the following drugs can induce thyroiditis?
a. methimazole
b. zyprexa
c. amiodoarone
d. a & c
c. amiodarone. This drug may also induce hypothyroidism.
What test can you do to make the diagnosis of Hashimoto’s thyroiditis?
Anti-TPO Abs (aka anti-peroxidase Abs); anti TPO Abs are a marker of the immune process but not pathogenic of the dysfunction
A thyroid exam reveals a firm gland. On U/S the gland has a moth eaten appearance. What is your spot diagnosis? What test could you do to confirm your diagnosis?
Hashimoto’s Thyroiditis; Anti-TPO Abs
A thyroid scan (I-123) reveals diffuse uptake. What is your spot diagnosis?
Graves’ disease
A thyroid uptake (I-131) reveals no uptake. What is your spot diagnosis?
Thyroiditis
When should you be suspicious for thyroid malignancy?
Be suspicious of malignancy if: rapid growth (especially if on synthroid), hard nodule, fixated/immobile, hoarseness (vocal cord paralysis), lymphadenopathy. Be even more suspicious if extreme of age (70) with a solitary nodule, large solitary nodule >4cm, or symptoms of compression.
