Thyroid Function

The thyroid gland produces hormones that influence metabolism, body temperature, heart rate, and energy levels. When thyroid function shifts, the effects can be subtle and develop gradually. Measuring TSH alongside the active thyroid hormones Free T3 and Free T4 can provide a clearer picture of thyroid activity than testing TSH alone.

This test may be relevant for:

• People experiencing unexplained fatigue, weight changes, or mood shifts
• Those with a family history of thyroid conditions
• Anyone who has previously had abnormal thyroid results and wants to follow up
• People who are curious about their thyroid function as part of a general health check

This panel includes three thyroid markers:

• TSH (Thyroid-Stimulating Hormone): produced by the pituitary gland, it signals the thyroid to produce hormones. It is often the first marker to shift when thyroid function changes.
• Free T4 (Thyroxine): the main hormone produced by the thyroid. It circulates in the blood and is converted to the more active T3 in tissues.
• Free T3 (Triiodothyronine): the more active thyroid hormone that directly influences metabolism and energy at the cellular level.

TSH is typically the most sensitive marker for thyroid changes. An elevated TSH with low Free T4 may suggest reduced thyroid function (hypothyroidism), while a suppressed TSH with elevated Free T4 or Free T3 could point toward an overactive thyroid (hyperthyroidism). Subclinical patterns, where TSH is slightly abnormal but T3 and T4 remain within range, can also be identified.

These markers together provide more context than TSH alone and can help guide a conversation with your healthcare provider.

This test uses a blood sample collected at a certified sample point (afnamepunt). With over 750 partner locations across the Netherlands, you can choose a convenient location. A trained phlebotomist performs the blood draw. Results are typically available within a few working days.

This test may be useful when:

• You experience symptoms that could be related to thyroid function, such as fatigue, sensitivity to cold or heat, or unexplained weight changes
• You have a known thyroid condition and want to monitor your levels
• A previous blood test showed a borderline TSH value
• You want to include thyroid markers in a broader health overview

Each marker is shown with your value and the reference range. TSH, Free T3, and Free T4 are best interpreted together, as the relationship between them provides context. For example, a TSH at the upper end of the range with a Free T4 at the lower end may tell a different story than either value alone.

Your report includes explanations for each marker. A healthcare provider can help determine whether your results suggest a need for further evaluation.

No specific preparation is needed for this test. Staying well hydrated before your appointment may make the blood draw more comfortable. If you are taking thyroid medication, follow your usual routine unless your healthcare provider advises otherwise.

Your results are typically available within a few working days. The report shows your values with reference ranges and clear explanations. If any marker falls outside the expected range, this is highlighted. We recommend discussing the results with a healthcare provider, especially if you are experiencing symptoms or have a history of thyroid concerns.