Gen Thyroid 1
Most common cause of primary hypothyroidism
Hashimoto (chronic lymphocytic) thyroiditis
Describe lab pattern for nonthyroidal illness syndrome
Low TSH, low or normal fT4 and T3 (in setting of critical illness)
Treatment for myxedema coma, other than supportive measures
IV T4 + steroids (hydrocortisone)
- exclude concurrent adrenal insufficiency
Next step for incidental thyroid nodule >1cm associated with low TSH
Radioactive iodine uptake scan (suspicious for autonomously functioning adenoma)
- confirmed hot nodules do not need FNA
This form of thyroid cancer is the least common, making up 4% of all cases, and may be associated with MEN 2A & 2B
Medullary thyroid cancer
This specific blood pressure abnormality is associated with hypothyroidism
Diastolic hypertension
In nonthyroidal illness syndrome, TFTs normalize in _____, after recovery from acute illness
4-8 weeks
Expected Levothyroxine dose change during pregnancy
Increase by 30-50%, usually 1st trimester
Next step for incidental thyroid nodule & normal or high TSH
Thyroid ultrasound
- if high-risk features, proceed to FNA
Strongest environmental risk factor for thyroid cancer
Radiation exposure to thyroid during childhood (<15 yrs old, but especially <5 yrs old)
Name 3 potential triggers for myxedema coma
Acute medical event, surgery, opiates
Frequency of thyroid function testing in pregnancy
Every 4 weeks
Name 2 patient groups where you would "start low and go slow" with Levothyroxine dosing
Age >60 years, history of CAD
Indication for thyroidectomy in multinodular goiter with no evidence of malignancy
Local compressive symptoms (airway, esophageal, neurovascular)
Treatment for medullary thyroid cancer
Total thyroidectomy + central neck dissection
Name 3 causes of medication-induced hypothyroidism
Lithium, interferon, IL-2, amiodarone, iodine
Levothyroxine should be taken _____ and at least _____ before food
on empty stomach; 1 hour
Recommended Levothyroxine start dose for hypothyroid patients <60 years old
1.6 micrograms/kg/day
Name at least 2 treatment options for hyperfunctioning solitary thyroid nodules
Radioactive iodine ablation, surgery, methimazole
This test is recommended before surgery in medullary thyroid cancer, to exclude MEN-associated pheochromocytoma
RET proto-oncogene testing
Name 3 possible consequences of overt/untreated hypothyroidism in pregnancy
Fetal neurocognitive impairment, premature birth, low birth weight, increased risk of miscarriage, increased risk of fetal death
Name 3 OTC supplements/meds that can interfere with Levothyroxine absorption
Calcium, iron, PPIs, psyllium
Name 3 indications for treating subclinical hypothyroidism
TSH >10, symptomatic, pregnant or planning pregnancy
Name 3 high-risk ultrasound findings for a thyroid nodule that would indicate FNA
microcalcifications, irregular margins, hypoechoic
In addition to thyroidectomy/lobectomy and levothyroxine suppression, radioactive iodine therapy is used to treat non-medullary thyroid cancer for these 3 indications
Extrathyroidal extension, metastatic disease, poorly differentiated/aggressive histology