Thyroid panel
Test Overview
The Thyroid Panel is a group of blood tests that evaluate thyroid function by measuring levels of thyroid hormones and thyroid-stimulating hormone (TSH). The thyroid gland plays a crucial role in metabolism, energy production, and overall endocrine balance. Abnormal thyroid hormone levels can indicate hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid).
Test Types
- TSH (Thyroid-Stimulating Hormone): Regulates thyroid hormone production.
- Free T4 (Thyroxine, unbound): Measures the active form of T4 in circulation.
- Total T4 (Thyroxine, bound and unbound): Measures total thyroxine in the blood.
- Free T3 (Triiodothyronine, unbound): Active form of T3, essential for metabolism.
- Total T3 (Triiodothyronine, bound and unbound): Measures total T3 in circulation.
- T3 Uptake: Evaluates how much T3 is available to cells.
- Reverse T3 (rT3): Occasionally tested to assess thyroid function under stress.
- Thyroid Antibodies (TPO, TG Antibodies): Helps diagnose autoimmune thyroid disorders like Hashimoto’s thyroiditis or Graves’ disease.
Thyroid Panel Test Results & Ranges
| Test Component: | Normal Range: | Abnormal (Possible Conditions): |
|---|---|---|
| TSH | 0.4–4.0 mIU/L | High: Hypothyroidism Low: Hyperthyroidism |
| Free T4 (FT4) | 0.8–1.8 ng/dL | High: Hyperthyroidism Low: Hypothyroidism |
| Total T4 (T4) | 5.0–12.0 µg/dL | High: Hyperthyroidism Low: Hypothyroidism |
| Free T3 (FT3) | 2.3–4.2 pg/mL | High: Hyperthyroidism Low: Hypothyroidism |
| Total T3 (T3) | 80–200 ng/dL | High: Hyperthyroidism Low: Hypothyroidism |
| T3 Uptake | 24–39% | High: Hyperthyroidism Low: Hypothyroidism |
| Reverse T3 (rT3) | 9.2–24.1 ng/dL | High: Chronic illness, stress |
| Thyroid Peroxidase Antibodies (TPOAb) | <35 IU/mL | High: Hashimoto’s or Graves’ disease |
| Thyroglobulin Antibodies (TgAb) | <20 IU/mL | High: Autoimmune thyroid disease |
Expected Turnaround Time
- Results Available: 1–3 business days
Specimen Requirements
- Sample Type: Blood sample (venipuncture)
- Container: Serum separator tube (SST)
Collection Instructions
- Fasting is not required, but some doctors may recommend fasting for consistent results.
- Avoid biotin supplements for at least 24–48 hours before testing, as they can interfere with results.
- Inform your healthcare provider about medications, especially thyroid hormones, steroids, and birth control pills, as they can impact hormone levels.
- Storage: Blood samples should be processed promptly and stored according to lab protocols, typically refrigerated or at room temperature until testing.
Test Details
Clinical Use: Diagnoses thyroid disorders: Helps detect hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). Monitors thyroid treatment: Ensures proper dosing of levothyroxine (Synthroid) or anti-thyroid medications. Detects autoimmune thyroid diseases: Identifies conditions like Hashimoto’s thyroiditis and Graves’ disease. Assesses metabolic and hormonal health: Thyroid hormones influence weight, energy levels, and heart function.
Limitations: TSH alone may not provide a full picture, so Free T4 and Free T3 levels are often included. Thyroid levels fluctuate due to stress, illness, and medication use. Pregnancy and menopause can impact thyroid function, requiring additional monitoring.
The Thyroid Panel is a crucial test for assessing thyroid function, diagnosing disorders, and managing treatment, ensuring optimal hormonal balance and overall well-being.