In January 2011, Melbourne Pathology is introducing a new thyroid function testing method that will provide significantly better precision for most immunoassays. This new test will also provide better correlation between fT4 and fT3, as well as better concordance between suppressed TSH and elevated fT4.
The new method generates TSH levels that are higher than the values associated with the current method, especially with very high fT4 and fT3 results. This means that doctors will need to attune themselves to a new set of reference intervals.