The normal concentration of the free fraction of T4 lies between 9 and 24 pmol/l (0.7 and (1.9 ng/100ml), whereas the total T4 concentration lies between 50 and 140 nmol/l (4ΓÇô11 ┬╡g/l00ml). The normal concentration of free T3 lies between 5 and 10pmol/l (0.33 and 0.65ng/l00ml), and that of total T3 between 1 and 3nmol/l (65 and 195ng/l00ml). The level of free hormones governs the metabolic state and thyroid status of a patient.
