Thyroid Function Test (TFT)

A complete thyroid assessment measuring TSH, free T3, and free T4 — the three markers needed to properly evaluate thyroid function. Standard GP screening typically only includes TSH, which can miss subclinical thyroid dysfunction where TSH is borderline but the active hormones (T3/T4) are already abnormal. Thyroid disorders affect approximately 1 in 20 Australians and are 5-8 times more common in women.

The thyroid gland produces hormones that regulate metabolism, energy, body temperature, heart rate, mood, and cognitive function. Dysfunction — either overactive (hyperthyroidism) or underactive (hypothyroidism) — produces symptoms that overlap with dozens of other conditions, making it one of the most commonly missed diagnoses. TSH (thyroid-stimulating hormone) from the pituitary gland is the standard screening marker — elevated TSH suggests hypothyroidism, suppressed TSH suggests hyperthyroidism. However, TSH alone misses subclinical cases where the pituitary is compensating for early thyroid failure by producing more TSH, but free T3 and T4 are already declining. Free T4 (thyroxine) is the primary thyroid hormone produced in large quantities, while free T3 (triiodothyronine) is the active form that enters cells and drives metabolic effects. Poor T4-to-T3 conversion — which occurs with stress, inflammation, calorie restriction, and certain nutrient deficiencies — can cause hypothyroid symptoms even with normal TSH and T4. This panel is essential for anyone with fatigue, unexplained weight changes, cold sensitivity, hair loss, constipation, anxiety, or family history of thyroid disease. No fasting required, though morning collection is recommended for consistent TSH readings.