Recognize appropriate interpretation of thyroid function tests.

Explanation:

Could this objective have been any broader?!

Well- thyroid function tests are the most important tests to interpret in endocrinology therefore it is vital to review them now. Thyroid has already been discussed in two other pages endo7.htm and endo8.htm.

Here we can discuss hyperthyroidism which has not been discussed yet. At a later stage we shall go through sick euthyroid syndrome as well.

In hyperthyroidism - total T4 is elevated unless  the patient hasT3 toxicosis(which is rare-but not on the boards) where T4 will be low.

TSH will be low unless the hyperthyroidism is Pituitary driven (secondary) toxicosis(See important principles).

Toxicosis due to thyroiditis and factitious administration will also have  low TSH and High T4 and a low thyroid uptake scan but thyroglobulin in thyroiditis is elevated but in external administration of thyroxine it is low.

In Grave's disease there are eye signs and positive TSH receptor blocking antibody. Iodine uptake by thyroid is high.