In this short video from our Thyroid Disease Masterclass course, endocrinologist Tracy Tylee, MD will teach you about the differences between primary and secondary hypothyroidism, and what to do when you suspect hypothyroidism but your patient's TSH levels are normal.
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Using simple illustrations and elegant animations, we review the pathophysiology of thyroid dysfunction, discuss the interpretation of thyroid tests, explain how pregnancy and certain medications can alter thyroid function, and evaluate the best treatment options. This course will prepare you to confidently assess and effectively manage patients with thyroid disease.
[00:00:00] Hypothyroidism is associated with low levels of thyroid hormone. This can be due to a problem with the thyroid, where the thyroid is unable to produce adequate levels of thyroid hormone, which leads to decreased inhibition at the level of the pituitary and an increase in TSH levels. Patient's labs will show low levels of thyroid hormone, with an elevated TSH level. Occasionally, patients can also have problems with their pituitary gland, where the pituitary is unable to secrete adequate amounts
[00:00:30] of TSH. This leads to decreased stimulation of the thyroid and low levels of thyroid hormone. These patients will present with low levels of thyroid hormone but a low TSH. When you suspect hypothyroidism, the first lab to check is the TSH, as this is the most sensitive marker of underlying thyroid abnormalities. If the TSH is elevated, you confirm the diagnosis of hypothyroidism with a T4. However, if your clinical suspicion for hypothyroidism is high and your TSH comes back normal
[00:01:00] or low, you do want to check a T4 level to check for the possibility of secondary hypothyroidism.