The T3 Uptake test assesses the amount of available thyroid hormone binding sites on proteins in your blood. This test can help your healthcare provider diagnose thyroid-related conditions.

T3 Uptake is a diagnostic test that indirectly measures thyroid hormone binding capacity, despite its misleading name.

Key Characteristics: • Does not directly measure T3 hormone uptake by cells • Evaluates extent of thyroid-binding protein saturation • Provides insights into thyroid hormone availability

Normal Range: • Adults: 25-35% • Varies slightly by age and sex • Specific ranges differ between laboratories

Clinical Significance: • Helps diagnose thyroid disorders • Indicates potential: • Hyperthyroidism • Hypothyroidism • Thyroid hormone binding protein abnormalities

Interpretation Guidelines: •

Low T3 Uptake may indicate: • Higher thyroid-binding globulin (TBG) levels • Pregnancy • Liver diseases • Increased estrogen

High T3 Uptake may suggest: • Lower TBG levels • Calorie deficit diets • Diabetes • Certain medications

The test provides valuable context when combined with other thyroid function assessments.