Thyroid Function Test

A thyroid screening measuring TSH (thyroid stimulating hormone) with reflex testing of free T4 if TSH is found to be abnormal. This stepwise approach is the standard clinical protocol for efficient thyroid evaluation.

The thyroid gland is a small but enormously influential organ that sets the metabolic pace for virtually every cell in the body. Thyroid dysfunction — whether overactive (hyperthyroidism) or underactive (hypothyroidism) — can produce a wide range of symptoms including fatigue, weight changes, temperature sensitivity, mood disturbance, hair thinning, and altered heart rate. Because these symptoms are non-specific and overlap with many other conditions, thyroid function testing is one of the most commonly requested blood tests. OneDayClinic uses a clinically efficient stepwise protocol: TSH (thyroid stimulating hormone) is measured first as the most sensitive screening marker. TSH is produced by the pituitary gland and rises when thyroid output is insufficient, or falls when the thyroid is overproducing hormones. If TSH is within the normal range, thyroid function is considered adequate and no further testing is needed. If TSH is abnormal — either elevated or suppressed — free T4 (thyroxine) is automatically measured from the same blood sample to characterise the pattern. This reflex testing approach avoids the unnecessary cost of measuring free T4 when TSH is normal, while ensuring that abnormal results are immediately investigated further. The test is suitable for individuals experiencing unexplained fatigue, weight gain or loss, temperature sensitivity, or mood changes, and for those with a family history of thyroid disease who want to establish a baseline.