The thyroid gland regulates metabolism, energy production, growth, and development through hormones T3 and T4.

TSH, secreted by the pituitary gland, controls thyroid hormone production.

Clinical uses include:

Diagnosing hypothyroidism (underactive thyroid).

Detecting hyperthyroidism (overactive thyroid).

Monitoring thyroid replacement therapy.

Evaluating goiter, thyroid nodules, and autoimmune thyroid disease.

Often performed as a first‑line screening test for thyroid dysfunction.

Analytes:

T3 (Triiodothyronine): Active thyroid hormone regulating metabolism.

T4 (Thyroxine): Major thyroid hormone, converted to T3 in tissues.

TSH (Thyroid Stimulating Hormone): Pituitary hormone that regulates thyroid function.

Normal Ranges (may vary by lab):

T3: ~80–200 ng/dL

T4: ~5–12 µg/dL

TSH: ~0.4–4.0 mIU/L

Abnormal Findings:

High TSH + Low T3/T4: Hypothyroidism.

Low TSH + High T3/T4: Hyperthyroidism.

Borderline or mixed results: May indicate subclinical thyroid disease or pituitary dysfunction.

Clinical Use:

Provides a comprehensive assessment of thyroid gland function.

Helps guide diagnosis, treatment, and monitoring of thyroid disorders.

Supports endocrinology and internal medicine evaluations.