What is tsh with reflex to ft4?

"TSH with reflex to FT4" is a laboratory test that measures the levels of two hormones in the blood, thyroid-stimulating hormone (TSH) and free thyroxine (FT4).

TSH is a hormone produced by the pituitary gland that stimulates the thyroid gland to produce and release the hormones thyroxine (T4) and triiodothyronine (T3). TSH levels can indicate whether the thyroid gland is functioning normally or not. High TSH levels indicate an underactive thyroid gland, while low levels suggest an overactive gland.

FT4 is a hormone produced by the thyroid gland that helps regulate metabolism. It is the active form of T4 that is free and not bound to proteins in the blood. Measuring FT4 levels can help diagnose thyroid disorders, particularly hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid).

The "reflex" part of the test means that if the TSH levels are outside the normal range, a second test will automatically be performed to measure the FT4 level. This is because TSH levels are often the first indicator of thyroid dysfunction, but measuring FT4 levels provides more specific information on the type and severity of the disorder.

This test is commonly used to diagnose and monitor thyroid disorders, as well as to evaluate the effectiveness of thyroid hormone replacement therapy. It is important to note that other factors, such as medications and medical conditions, can affect TSH and FT4 levels, so the results of this test should be evaluated in conjunction with other medical information.