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  • For Educational Purposes Only: This content is intended for educational reference and should not be used for clinical decision-making.
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Panel Overview

The Thyroid Panel (also called Thyroid Function Tests or TFTs) evaluates the function of the thyroid gland, which regulates metabolism, energy production, and numerous bodily functions. This panel measures thyroid-stimulating hormone (TSH) from the pituitary gland and thyroid hormones (T4 and T3) produced by the thyroid gland itself.

Thyroid disorders are among the most common endocrine conditions, affecting millions of people worldwide. Hypothyroidism (underactive thyroid) causes fatigue, weight gain, and cold intolerance, while hyperthyroidism (overactive thyroid) causes weight loss, anxiety, palpitations, and heat intolerance.

Clinical Applications

  • Hypothyroidism Diagnosis: Elevated TSH with low Free T4 indicates primary hypothyroidism (Hashimoto's thyroiditis)
  • Hyperthyroidism Diagnosis: Suppressed TSH with elevated Free T4/T3 indicates hyperthyroidism (Graves' disease)
  • Levothyroxine Monitoring: TSH is primary marker for thyroid hormone replacement dose adjustment
  • Subclinical Disease Detection: Subclinical hypothyroidism (elevated TSH, normal Free T4)
  • Pregnancy Screening: Thyroid dysfunction affects fetal development; lower TSH targets in pregnancy
  • Symptom Evaluation: Unexplained fatigue, weight changes, temperature intolerance, mood changes

Thyroid Panel Components

TSH

Normal: 0.4-4.0 mIU/L

Thyroid-Stimulating Hormone from pituitary gland. Best single screening test for thyroid function. Elevated in hypothyroidism, suppressed in hyperthyroidism.

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Free T4

Normal: 0.8-1.8 ng/dL

Unbound thyroxine, the metabolically active form. Primary thyroid hormone measured for diagnosis. Not affected by binding protein levels.

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Free T3

Normal: 2.3-4.2 pg/mL

Unbound triiodothyronine, the most metabolically active thyroid hormone. Useful in hyperthyroidism diagnosis (T3 toxicosis).

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Total T4

Normal: 4.5-12.0 μg/dL

Total thyroxine (bound + unbound). Affected by thyroid-binding globulin levels. Free T4 preferred for diagnosis.

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Total T3

Normal: 80-200 ng/dL

Total triiodothyronine (bound + unbound). Less commonly ordered. Useful for T3 toxicosis or amiodarone-induced dysfunction.

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