OneDayTests Thyroid Function Blood Test
Type
Blood Testing
Biomarkers
3
Duration
30 min
Results
48 hours
Comprehensive thyroid function blood test measuring T3, T4, and TSH levels.
This test measures three key thyroid hormones: free T3, free T4, and TSH. It provides a comprehensive assessment of thyroid function, helping to identify both underactive (hypothyroidism) and overactive (hyperthyroidism) conditions. Early detection is crucial for managing thyroid disorders and preventing long-term health complications. The test is beneficial for individuals experiencing symptoms like weight changes, fatigue, or mood disturbances, or those with a family history of thyroid issues.
Key Details
Who Is This For?
Anyone experiencing unexplained fatigue, weight changes, hair loss, cold sensitivity, or mood disturbances. People with a family history of thyroid disease or autoimmune conditions. Women planning pregnancy, as thyroid function is critical for fetal brain development. Anyone who has had a 'normal' TSH result but still suspects thyroid dysfunction.
What's Included
Preparation Required
No fasting required for a standalone thyroid panel. If you take thyroid medication (levothyroxine/Synthroid), take your dose after the blood draw, not before — taking it beforehand can temporarily spike T4 levels and skew results. Morning testing is recommended for the most consistent TSH readings, as TSH follows a circadian rhythm and peaks overnight.
Biomarkers Tested
3The unbound, active form of the main thyroid hormone T4. Free T4 directly reflects thyroid gland output and is used alongside TSH to diagnose and monitor thyroid disorders.
The active form of thyroid hormone responsible for regulating metabolism, energy, and body temperature. Free T3 is converted from T4 in tissues and is three to four times more potent than T4.
The primary screening test for thyroid function. TSH is produced by the pituitary gland to regulate thyroid hormone production. High TSH indicates an underactive thyroid (hypothyroidism), while low TSH suggests an overactive thyroid (hyperthyroidism).
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- Category
- Diagnostic
- Sample Type
- Blood draw
- Duration
- 30 min
- Results
- 48 hours
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