What is a thyroid?
The thyroid is a gland in the neck, above the collarbone, shaped like a butterfly. The thyroid is one of the endocrine glands which produce hormones. These thyroid hormones help regulate the rate of many activities in the body, such as how fast calories are burned and how fast the heart beats.
What is the purpose of this test?
Order this Thyroid #2 Essential Blood Test Panel plus Reverse T3 to provide a detailed evaluation of thyroid function for individuals showcasing signs of thyroid disorder. In addition, individuals may use this panel to evaluate pituitary gland function, assess the severity of thyroid disorder, monitor treatment, and detect potential side effects.
Thyroid Panel with Thyroid-Stimulating Hormone (TSH) - Thyroid function is critical to your metabolism and affects your energy level, heart rate, weight control, and more. The thyroid-stimulating hormone is produced in the pituitary gland and stimulates the production of thyroid hormones. The TSH helps identify an underactive or overactive thyroid state. This comprehensive evaluation of your thyroid hormone levels includes T-3 Uptake, T4, Free Thyroxine Index (T7), and Thyroid-Stimulating Hormone (TSH).
Free T3 - normally represents only approximately 5% of the thyroid hormone. Like thyroxine, it is almost entirely bound to the carrier proteins, with only 0.25% of the total being free. Measurement of Free T-3 is of value in confirming the diagnosis of hyperthyroidism when an elevated free or total thyroxine level is found. Abnormal total and free tri-iodothyronine concentrations can appear in T3 toxicosis in normal thyroxine levels. Free T3 levels are not affected by carrier protein variation.
Free T4 - is the active form of thyroxine and is a more accurate reflection of thyroid hormone function. The free T4 test is thought to be a more accurate reflection of thyroid hormone function, and, in most cases, its use has replaced that of the total T4 test. A total T4 or free T4 test is primarily ordered in response to an abnormal TSH result. However, sometimes the T4 will be ordered along with a TSH to give the doctor a complete evaluation of the adequacy of the thyroid hormone feedback system. These tests are usually ordered when a person has symptoms of hyperthyroidism or hypothyroidism.
Reverse T3 - is a biologically inactive form of T3, or triiodothyronine, one of two major hormones produced by the thyroid (the other is T4, or thyroxine). Under normal conditions, the body converts T4 to T3 and RT3 in specific ratios. In certain circumstances, the amount converted to RT3 rises, such as when the body is under stress, as in severe or acute illness or injury. Drugs such as amiodarone and glucocorticoids can also cause increased RT3 levels. However, RT3 levels alone may not indicate a thyroid condition since stress can cause rising levels. A more accurate assessment may be gained by combining the Reverse T3 Test with the Free T3 Test to evaluate the ratio between RT3 and free T3 levels.
When should I order the Thyroid #2 Essential Blood Test Panel plus Reverse T3?
Individuals may order this panel if they suspect a thyroid disorder. Common signs or symptoms associated with thyroid malfunction or disorders include:
- Fatigue
- Weight loss or gain
- Chills
- Painful joints and muscles
- Dry skin
- Thin/dry hair
- Irregular heart rate
- Constipation
- Depression and anxiety
- Mood swings
- Irregular menstrual periods
- Infertility
- Insomnia
- Frequent bowel movements
