Most useful test in assessing the thyroid function

T3

A glycoprotein stored in the follicular colloid and serves a preformed matrix containing tyrosyl residues.

Level of serum TSH in subclinical hypothyroidism.

Considered as the "Pre-Hormone".

Metabolically active form of Thyroid hormone.

If the thyroid hormone is not secreted, the TSH level will be very high in an attempt to stimulate the gland to secrete more.

Highest affinity for T4 and T3.

This hormone stimulates the thyroid gland to produce and release thyroid hormones.

Serum T4/T3 level in subclinical hypothyroidism.

Membrane-bound enzyme produced by the follicular cells and functions by lodination and coupling of the iodotyrosine residues in the thyroglobulin.

This is an inactive form of T3 which is eliminated quickly by the body after inner ring deiodination.

If the patient's thyroid gland is producing much thyroid hormone, then the circulating TSH will be suppressed.

Free T4

T3 of 71 ng/dL. T4 of 2.2 ug/dL, TSH of 9.4 mIU/L.T3 of 71 ng/dL. T4 of 2.2 ug/dL, TSH of 9.4 mIU/L.

TSH of 0.26 mIU/L, T3 of 144 ng/dL, T4 of 6.9 ug/dL.

Hormones produced by the thyroid gland, except;

Low TSH, low T4, low T3.

Level of thyroid hormones in subclinical hyperthyroidism.

Ideal tumor maker for thyroid cancer patient treated with surgery and/or radioactive ablation.

Carries the majority of T4 in the bloodstream.

T4

FT4 of 3.3 ng/dL, T4 of 17.1 ug/dL, TSH of 0.13 mIU/L.

About 99% of the circulating thyroid hormone are unbound to proteins and are readily available for hormonal activity.

Hormone that signals the thyroid follicular epithelial cell to engulf the processed thyroglobulin through endocytosis.

TSH

T4 of 8.12 ug/dL, TSH of 7.08 mIU/mL, T3 of 111.4 ng/dL.

Level of thyroid hyperthyroidism.

Major site of action of Thyrotropin-releasing hormone.