Thyroid Hormone - Free T4

The best way to initially test thyroid function is to measure the TSH level in a blood sample.

Your thyroid is essential to your health and wellbeing. From how fast your heart beats to how quickly your body burns calories, your thyroid directly influences things as subtle as your mood and as vital as your fertility.

This test measures your Free T4 (thyroxine) which, in combination with TSH and possibly Free T3, can help to assess thyroid function and can screen for specific thyroid conditions, such as under-active thyroid (hypothyroidism) and overactive thyroid (hyperthyroidism).

TSH and T4 levels work interdependently (and often inversely) rising or falling in response to one another. For example, low T4 levels often cause TSH levels to rise signaling hypothyroidism, while high T4 levels often cause TSH to drop signaling

TEST PREPARATION: If you’re taking a supplement containing biotin (also called vitamin B7 or B8, vitamin H, or coenzyme R), commonly found in products promoting nail, skin, and hair health, it is recommended that you wait at least 72 hours from your last dose before sample collection.

[LC 001974]