Test : Thyroid function test
Indications : Thyroid hormone tests are done for the following reasons:
To rule out
hypothyroidism in newborns and adults
To rule out
hyperthyroidism
To assess treatment for hypo / hyperthyroidism
A sample of blood is drawn through venipuncture, transferred to a sterile container and taken to the laboratory. The procedure must be done on an empty stomach. Ask your doctor if you must stop taking your thyroid medications prior to the test. Certain other medications too affect the test results including blood thinners,
steroids and anti-seizures medications.
Physiology : Thyroid hormone tests are blood tests that are done to assess the functioning of the
thyroid gland.
The thyroid is a butterfly-shaped gland that is located in front of the windpipe, just below the voice box.With the help of
iodine absorbed from food it makes two hormones thyroxin (T4) and tri iodothyronine (T3), which are stored in the thyroid and released according to the bodys need.
Thyroid hormones, T3 and T4 are required for the proper functioning of the brain. During the first few years of life inadequate amounts of thyroid hormones cause intellectual disability. In adults, hypothyroidism, a condition producing low
thyroxin levels, affects metabolism and energy absorption.
Normal Range : T4-60-140nmol/L, T3-1.2-1.8nmol/L, TSH-0.1-6IU/L
Interpretation :
Thyroid hormone tests - Normal Values |
Total thyroxine (T4): |
11.822.6 (mcg/dL) in newborns
6.413.3 mcg/dL in babies and older children
5.411.5 mcg/dL (57148 nmol/L) in adults |
Free thyroxine (FT4): |
0.72.0 ng/dL nanograms per deciliter (ng/dL) |
Total triiodothyronine (T3): |
105245 ng/dL in children of age 114
82213 ng/dL in adolescents ages 1223
80200 ng/dL in adults |
Free triiodothyronine (FT3): |
260480 picograms per deciliter (pg/dL) or 4.07.4 pmol/L in adults |
Free thyroxine index (FTI): |
1.5-4.5 (index) in adults |
Higher than normal values could indicate the following:
Graves disease
Thyroiditis
Goiter
Over consumption of thyroid medications
Lower than normal values could indicate the following:
Thyroid disease - Thyroiditis
Pituitary gland disease
Thyroid gland damage through radiation / surgery
References :
1. http://www.webmd.com/women/thyroid-hormone-tests?page=4
i have thyroid problem because of which i have gained weight i.e. obese, i am taking thyronorm 150 mcg...I have many problems as i said earlier i am obese, i am not having my menstruation properly...how to decrease weight and get back my periods...i have shown atleast to four to five doctors (gynecologist as well as endocrinologist) but all of them think me an experiment material and just give medicines and tell all will be normal....no one has cured my problems....only mint money and test on me...please help