Thyroid Basic Screen (TSH + fT4)

IFCOR's Thyroid Basic Screen is a targeted two-marker test — TSH and free T4 — that confirms whether the thyroid gland is functioning within normal limits. TSH (thyroid-stimulating hormone) is the pituitary's signal to the thyroid; abnormal TSH is the earliest indicator of hypothyroidism or hyperthyroidism in over 95% of cases. Free T4 is the main thyroid hormone produced in response to TSH, and measuring both together distinguishes primary thyroid disease from secondary pituitary problems. At 450 Kč, this is the most affordable entry point for anyone with unexplained weight change, fatigue, hair loss, temperature sensitivity, or mood changes who wants to check thyroid function before a GP consultation.

The thyroid gland regulates basal metabolic rate, body temperature, heart rate, protein synthesis, and the metabolism of fats and carbohydrates — functions that, when impaired, produce wide-ranging and often non-specific symptoms. Hypothyroidism (underactive thyroid) may present as fatigue, weight gain, cold intolerance, constipation, dry skin, hair thinning, depression, and slowed reflexes. Hyperthyroidism (overactive) presents as weight loss despite normal appetite, heat intolerance, palpitations, anxiety, sweating, and diarrhoea. In both cases, TSH is the most sensitive first-line test because the pituitary responds to even subtle changes in circulating thyroid hormone levels. TSH rises when thyroid output falls (hypothyroidism) and falls when output is excessive (hyperthyroidism), providing a logarithmic amplification of small changes in free hormone levels. Free T4 (thyroxine unbound to carrier proteins) is the active pool of the main thyroid hormone and is measured alongside TSH to distinguish primary thyroid disease (abnormal TSH + abnormal fT4) from secondary or tertiary disease (abnormal TSH + normal fT4, suggesting a pituitary or hypothalamic problem). This two-marker screen is the standard first investigation recommended by Czech endocrinology guidelines and by European Thyroid Association guidance for symptomatic screening. Fasting is preferred but not strictly required for TSH/fT4 testing. Results are delivered by secure email the next business day from IFCOR's ISO 15189-accredited laboratory. If TSH or fT4 is abnormal, the Thyroid Comprehensive panel (TSH + fT4 + fT3 + antibodies) may be the appropriate next step, and the laboratory result can be taken directly to a physician.