Thyroxine (T4) Test

The Thyroxine (T4) Test at Pamel Laboratories measures the level of T4 hormone, one of the main hormones produced by the thyroid gland. T4 plays a vital role in regulating metabolism, body temperature, growth, and energy use. This test is a key component in evaluating thyroid health, especially when used alongside TSH and T3 tests.

T4 exists in two forms: Total T4, which includes both bound and free hormone, and Free T4, which measures only the active, unbound form circulating in the bloodstream.

What the Test Measures:

• The level of Thyroxine (T4) in the blood

• Helps assess thyroid function and hormonal balance

Purpose of the Test:

• Diagnose or monitor:

  • Hypothyroidism (underactive thyroid)

  • Hyperthyroidism (overactive thyroid)

• Evaluate symptoms such as:

  • Fatigue or weight changes

  • Hair thinning or dry skin

  • Menstrual irregularities

  • Mood changes

• Monitor:

  • Thyroid hormone therapy

  • Post-surgical thyroid function

Sample Type: Blood sample (serum)
Fasting Required: No
Turnaround Time: 24–48 hours

Interpretation Guide:

• High T4: May indicate hyperthyroidism, thyroiditis, or overmedication

• Low T4: May suggest hypothyroidism, pituitary gland issues, or illness-related suppression

Interpretation is most accurate when combined with TSH and T3 levels