Most reference ranges are the same for individuals as well as the population, but for T3, T4 and TSH, the healthy “set point,” the healthy range of variation, for any single individual covers a range that is approximately 50% narrower than the statistical reference range. Thyroid hormone references are very unlike most other blood test reference ranges. Individual set-pointsįrom the perspective of the biological organism, a state of thyroid hormone deficiency or excess is NOT relative to a population-wide statistically determined reference range, but is rather relative to that individual’s “set-point” for euthyroidism. Today, thyroid therapy is held hostage to the tyranny of statistical reference ranges and patients are suffering from doctors who are unaware of the controversies. Likewise, TSH values above the reference range are rare, seen in less than 5% of healthy humans, but in many cases, patients are declared “subclinically” hypothyroid (doctors are told to refrain from a diagnosis and withhold therapy) until their TSH exceeds 10 miU/L.
NORMAL THYROID LEVELS FREE
With any blood test reference range, is easy for a doctor to forget that “normal” is based on a statistical calculation of 95% of the norm, but the average could be anywhere within that range, and the average may differ based on sub-populations.Ī Free T3 near the bottom of reference range may be seen in less than 5% of healthy humans, but many a doctor will deem it “normal” for a patient to remain with borderline low T3 for decades, unaware that in a normal-thyroid patient, such lows would be temporary (only during illness).ĭuring health, the average Free T3 level is in the mid to upper half of reference, as seen in the levels of 3,875 healthy, untreated euthyroid controls in Gullo et al’s 2011 article on levothyroxine monotherapy.
In medical practice, the laboratory reference range is the measure used to define the hypothyroid state, and it aids clinical decision-making.
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