T4 Blood Test

Thyroxine (T4) Blood Test
Free T4

Total Thyroxine (TT4): The TT4 test measures both bound and unbound thyroxine levels. TT4 does not give the activity of T4 when measured alone. This test is best completed with a T3 uptake.
TT4 Laboratory Reference Range: 5.4-­‐11.5 ug/d
TT4 Functional or Optimal Reference Range: 5-­‐12 ug/d

Free Thyroxine Index (FTI): As stated earlier, the total thyroxine and the T3 uptake must be used together to calculate the FTI. The FTI is measured by multiplying the TT4 levels by the T3 uptake levels. The result is the FTI and it determines the amount of active T4 available.

FTI Laboratory Reference Range: 4.6 – 10.9 mg/dl
FTI Functional or Optimal Reference Range: 1.3 to 4.8 mg/dl

Free Thyroxine (FT4): The free thyroxine test is used to measure the amount of free or active T4 in the blood.
FT4 laboratory range is 0.7 to 1.53 ng/dL.
FT4 optimal range is 0.8 to 2.2 mg/dL.

T4 – Thyroxine

Jan 262017
 

Thyroxine T4 is made by the thyroid and uses Selenium, Zinc and Iodine. The Liver converts T4 to T3 triiodothyronine.

TSH causes the thyroid gland to make two hormones: triiodothyronine (T3) and thyroxine (T4).

A normal level of T4 on its own may not be an indicator of normal thyroid function, because if the thyroid can’t convert the T4 to T3, due to a mineral deficiency or problem thyroid,  then the body is getting no benefit from the T4 in the blood stream.

Synthetic thyroxin such as Synthoid is T4, so if you are taking it, the T4 levels may show as correct even when the thyroid is not functioning properly.

Natural forms of desiccated thyroxin will normally contain a mix of both T4 and some T3.

Blood Tests for Thyroid Disfunction

Jan 262017
 

Typically your GP will ask for TSH test on your blood sample.

The TSH alone will not generally be a good indicator, a full suite of tests normally needs to be done.

TSH, FT4, FT3, TT4, FTI, Resin T3 Uptake, Reverse T3, TPO and TGB Antibodies.

 

Free  (T3) triiodothyronine

Reverse T3

Free (T4) thyroxine

TSH – thyroid-stimulating hormone

TSH is produced when the hypothalamus releases thyrotropin-releasing hormone (TRH). TRH then triggers the pituitary gland to release TSH. TSH causes the thyroid gland to make two hormones: triiodothyronine (T3) and thyroxine (T4).

Thyroid antibodies. TPO

  • Thyroid Peroxidase Antibodies (TPOAb)
  • Thyroglobulin Antibodies (TgAb)

This is because it is possible to have normal T4 and TSH levels yet still have low T3 if the body is not converting T4 to T3 sufficiently.

 

In addition other tests can provide more indicators,

for instance, having been diagnosed with a lump in the thyroid, as shown by ultrasound scan, and with having a fine needle biopsy being inconclusive, my specialist ordered the following:

PTH  Parathyroid hormone

TFT  Thyroid Function Test

CMP  Cmprehensive Metabolic panel

FBE  Full blood examination

Thy ABS –  thyroid antibodies  TPO

Vitamin D

CLE

COMP

 

 

A complete test might consist of the following:

Complete Metabolic Panel, not a basic metabolic panel. You have a thyroid disorder and you need as much information as POSSIBLE!

A complete thyroid panel which needs to include TSH, Free T3, Free T4, Total T4, Free Thyroxine Index, Resin T3 Uptake, TPO and TGB antibodies, TBG and Reverse T3.
You NEED to know as much about your thyroid gland as possible and ALL of these blood tests will tell you.

A complete lipid panel and a CBC with auto differential which breaks down the white and red blood cells.

Testing for gluten reactivity, gut function, cross-­‐ reactive foods and other parts of your body that your immune system could be attacking.

An ASI (Adrenal Stress Index) which checks your adrenal glands. Your adrenal glands are your “stress glands.”

A 2105 stool microbial test looking to see if you have parasites or h-­‐pylori or fungi or mold in your gut.

An Organic acid test which tests for carbohydrate metabolism, fatty acid metabolism, energy production markers, and detoxification markers to name a few.