Expanding on Thyroid Tests
FT3 & FT4 tests
FT3 and FT4 are the abbreviations for free triiodothyronine and free thyroxine. These are the hormones that are not bound to proteins in the blood and can enter and affect the body tissues. FT3 and FT4 tests measure the levels of these hormones in the blood and can help diagnose thyroid disorders.
FT3 and FT4 tests are usually done along with a TSH test, which measures the hormone that regulates the production of FT3 and FT4 by the thyroid gland. The TSH test is often the first test to check for thyroid function, as it can indicate if the thyroid problem is caused by the thyroid itself (primary) or by the pituitary gland (secondary).
These tests may be ordered by your doctor if you have symptoms of a thyroid disorder such as —
- weight changes
- fatigue
- mood swings
- hair loss
- irregular heartbeat
FT3 and FT4 tests may also be done if you have a family history of thyroid disease, or if you are taking medications that affect your thyroid function.
What is the normal range for FT3 & FT4?
The considered normal range of FT3 is 2.3 to 4.2 pg/dL (picograms per milliliter) and the normal range of FT4 is 0.7 to 1.9 ng/dL (nanograms per deciliter). Keep in mind, that these ranges may vary depending on the laboratory and the method used. Your doctor will interpret your results based on your symptoms, medical history, and other tests.
What do the results indicate?
A low level of FT4 or FT3 may indicate hypothyroidism, meaning your thyroid gland is not producing enough hormones.
Symptoms of hypothyroidism —
- weight gain
- cold intolerance
- dry skin
- constipation
- depression
- menstrual irregularities
A high level of FT4 or FT3 may indicate hyperthyroidism, meaning your thyroid gland is producing too much hormones.
Symptoms of hyperthyroidism —
- weight loss
- heat intolerance
- sweating
- anxiety
- tremors
- palpitations
What causes hypothyroidism & hyperthyroidism?
The causes of hypothyroidism and hyperthyroidism may vary depending on whether they are primary or secondary.
Primary hypothyroidism may be caused by —
- autoimmune diseases like Hashimoto’s thyroiditis
- iodine deficiency
- thyroid surgery
- radiation therapy
- certain medications
Primary hyperthyroidism may be caused by —
- autoimmune diseases like Graves’ disease
- thyroid nodules
- thyroiditis
- excessive iodine intake
Secondary hypo/hyper-thyroidism may be caused by problems with the pituitary gland or the hypothalamus that affect the secretion of TSH.
Finding yourself having any of the above symptoms? Fear not, for we are here to help you be sure if its Thyroid or a passing flu.
Let us help you with your worries. Book a test or an appointment with our in house doctors!
