Hello and welcome to the zero to finals podcast. My name is Tom and in this episode I'm going to

be talking to you about thyroid function tests. And if you want to follow along with written notes on

this topic, you can follow along at zero to finals.com slash tfts or in the endocrinology section of the zero to finals medicine book.

So let's get straight into it.

Thyroid stimulating hormone or TSA.

If you're concerned about possible thyroid disease,

you can use TSA alone as a screening test. When the thyroid stimulating hormone is

abnormal, then you can measure T3 and T4 to find out more information. In hyperthyroidism,

TSA is suppressed by the high thyroid hormones, so you get a low TSA level.

The exception is in a pituitary adenoma that's secreting TSA, in which case the TSA level will be high.

In hypothyroidism, the TSA level is high as it's trying to stimulate more thyroid hormone release.

The exception to this is when the pituitary gland or the hypothalamus is causing the hypothyroid.

And this is called secondary hypothyroidism, in which case the TSA level will be low,

because it's the low level of TSA level that's causing the low level of thyroid hormone.

T3 and T4.

In hypothyroidism, you expect raised T3 and raised T4 and suppression of T-SH.

In hypothyroidism, you expect low T3 and T4 and raised T. Auto-antibodies

Auto-antibodies indicate that there's an autoimmune condition

that's causing the pathology in the thyroid gland.

Antithyroid peroxidase or anti-tpo antibodies are antibodies against the thyroid gland itself.

And these are the most relevant thyroid auto-antibody in autoimmune thyroid disease.

And they're usually present in Graves Disease and Hashimoto's Theroditis.

...