Type
Blood Testing
Biomarkers
8
Duration
10 min
A comprehensive thyroid function panel measuring TSH alongside free T3 (fT3) and free T4 (fT4). While TSH indicates whether the pituitary perceives thyroid output as adequate, the free hormone levels reveal the actual circulating concentrations of active thyroid hormones. This three-marker combination distinguishes between primary and secondary thyroid disorders and quantifies the severity of any dysfunction detected.
The full thyroid panel provides the complete picture that a TSH-only test cannot. TSH tells you the pituitary's opinion of thyroid function, but free T3 and free T4 reveal the reality at the tissue level. Discordant results between TSH and the free hormones point to specific conditions: a high TSH with low fT4 confirms primary hypothyroidism, while a normal TSH with low fT3 may indicate a conversion problem where the body fails to activate the prohormone T4 into the metabolically active T3. Free T3 is particularly relevant for patients experiencing persistent symptoms despite seemingly normal TSH levels. T3 drives the majority of thyroid hormone effects at the cellular level — regulating metabolic rate, body temperature, heart rate, and cognitive function. Some individuals convert T4 to T3 inefficiently due to selenium deficiency, chronic stress, or genetic variation in deiodinase enzymes, a situation that TSH alone cannot detect. At SYNLAB München Zentrum, all three markers are measured from a single blood draw using automated immunoassay platforms. No fasting is strictly required, although morning collection provides the most consistent baseline values. Results are typically available within one to two working days. This panel is the standard follow-up when TSH screening yields abnormal results, and it serves as the preferred monitoring panel for patients on thyroid hormone replacement therapy.
Key Details
- Biomarkers
- 3
- Results
- 1-2 working days
- Fasting
- Not required
Who Is This For?
Abnormal TSH follow-up, thyroid medication monitoring, persistent fatigue despite normal TSH, comprehensive thyroid assessment
What's Included
Panel Categories
Biomarkers Tested
8The 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 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.
Free triiodothyronine; high levels indicate hyperthyroidism, low levels hypothyroidism.
Free thyroxine; high levels indicate hyperthyroidism, low levels hypothyroidism.
A group of proteins in blood including antibodies (immunoglobulins), transport proteins, and enzymes. Elevated globulin can indicate chronic infection, inflammation, or blood cancers. Calculated by subtracting albumin from total protein.
An inactive form of T3 produced when the body converts T4. Elevated reverse T3 can occur during illness, stress, or caloric restriction and may indicate impaired thyroid hormone activation despite normal TSH levels.
Antibodies against thyroid peroxidase, an enzyme essential for thyroid hormone production. Positive TPO antibodies indicate autoimmune thyroid disease, most commonly Hashimoto's thyroiditis, even before symptoms or TSH changes appear.
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).