Laboratory Tests and Screening

1.      Thyroid Function Tests

Overview

Thyroid Function Test comprises of various blood tests that are used to evaluate the functioning of thyroid glands. They include the T3, TSH, T4 and T3RU. The thyroid gland is situated in the lower front of the neck and is of significance in regulating blood processes. It produces hormone thyroxine (T4) and triiodothyronine (T3). Too much production of these hormones causes hyperthyroidism while less production leads to hypothyroidism.

The most common thyroid function tests are the T4 (thyroxine test) and TSH (thyroid-stimulating hormone) test. This section will highlight common thyroid function tests (TSH and free T4).

TSH

This test measures thyroid-stimulating hormone concentration in the serum, and it is preferred by many physicians as the initial test for people suffering from thyroid disease. This is because it is the key hormone in the diagnosis of hypothyroidism and hyperthyroidism. The availability of the advanced third-generation TSH assays has enhanced the possibility of detecting significantly decreased and raised levels in TSH, even TSH as low as <0.1mU/L.

Furthermore, third-generation TSHs are capable of accurately distinguishing between suppressed and normal results, as well as distinguishing between profoundly suppressed and mildly suppressed states. Thus they offer a powerful tool in estimation of the hyperthyroidism severity, differentiating between frank hyperthyroidism and the influences of some drugs and illnesses not related to thyroids in patients who suppress the levels of TSH in sick euthyroid disease as well as in the optimization of suppressive therapies.