Thyroid Blood Test and Diagnosis

There are approximately 27 million people in the United States with thyroid disease. About half of these cases remain undiagnosed. Thyroid disorder is an autoimmune disease that is comprised of two types:

Hyperactive Thyroid disease: Also known as hyperthyroidism, is characterized by an over abundance of thyroid hormone levels in the blood.

Hypoactive Thyroid disease: Or hypothyroidism, is marked by inefficient amounts of thyroid hormones in the blood.

The thyroid is an endocrine gland responsible for the production and secretion of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). It is the imbalance of these hormones that determine whether a person's thyroid is overactive or underactive. The diagnosis of a hyperactive or hypoactive thyroid is determined by performing certain tests which include:

Blood Tests For Thyroid Disease:

Thyroid Stimulating Hormone (TSH) Test:
A TSH level above 3.0 can be indicative of hypothyroid

Total T4/ Total Thyroxine:
Decreased Total T4 level and elevated TSH is possible underactive thyroid.
Free T4 / Free Thyroxine:
Decreased Free T4 level with an elevated TSH can mean underactive thyroid.
Total T3 / Total Triiodothyronine:
Decreased Total T3 level along with an elevated TSH may can be underactive thyroid.

Free T3 / Free Triiodothyronine:
Decreased Free T3 level and elevated TSH could be underactive thyroid.

Other blood tests include:
Thyroglobulin/Thyroid Binding Globulin/TBG
T3 Resin Uptake (T3RU)
Reverse T3
Thyroid Peroxidase Antibodies (TPOAb) / Antithyroid Peroxidase Antibodies
Antithyroid Microsomal Antibodies / Antimicrosomal Antibodies
Thyroglobulin Antibodies / Antithyroglobulin Antibodies
Thyroid Receptor Antibodies (TRAb)
Thyroid-Stimulating Immunoglobulins (TSI)

Thyroid Imaging:
Nuclear Scan / Radioactive Iodine Uptake (RAI-U): Determines can if a person has Graves' disease, toxic multinodular goiter, or thyroiditis.
CT Scan: Helps to detect and diagnose a goiter, or larger thyroid nodules.
MRI / Magnetic Resonance Imaging – Shows the size and shape of the thyroid
Thyroid Ultrasound: Detects if it is a cyst filled with fluid, or a solid tissue mass

Fine Needle Biopsy Aspiration:

Also known as fine needle aspiration (FNA) evaluates lumps, cysts, and nodules. A thin needle is inserted directly into the cyst to extract cells are withdrawn and checked for cancer. Ultra sound is used to ensure the placement of the needle into the cyst or nodule.

Other tests include:

Iodine Patch Tests
Saliva Testing
Urinary Testing
Basal Body Temperature Testing

Diagnosis:

Diagnostic thyroid tests are used to determine the following thyroid conditions:

Hypothyroidism
Hashimoto’s Disease
Hyperthyroidism
Graves’ Disease
Goiter
Nodules
Thyroid Cancer

Hyperthyroidism:

Hyperthyroidism, or Graves disease, can be determined through TSH, T4 (or Free T4), T3 (or Free T3) and Radioactive Iodine Update (RAI-U) testing.

Goiter:

Examination of swelling of the front lower aspect of the neck
A blood test to determine amounts of thyroid hormone being produced by the thyroid
Antibodies testing to determine autoimmune disease
An ultrasound test to assess the size of the enlargement
A radioactive isotope thyroid scan to produce an image of the thyroid. This procedure is not performed on women who are pregnant or who possibly may be pregnant, to prevent harming the fetus.

Nodules: To determine if they are benign or malignant (cancerous) are diagnosed via blood testing, radioactive iodine uptake, ultrasound, and/or needle biopsy.

by Barb Hicks, RN/LMT