[alan wales - dennis sparkes (OP)]

FT3:  triiodide level in pmol/L
FT4:  Thyroxine level in pmol/L
FTH:  FT3 + FT4 level in pmol/L

Equation:  100(FT3 / (FT4 + FT3)) = Percentage of FTH deionised   

Worked example of the equation:

Test Results:  FT3 = 3.5     FT4 = 18.2

100(3.5 / (18.2+3.5))

100(3.5 / (21.7))

100(0.161)

16.1%


Using the optimal T3/T4 ratio calculator in standard international units, we can show the accuracy of our equation. The optimal calculator gives a T3:T4 ratio of 1.61 with the same test results as used above. This is equal to the 16.1% result obtained using our equation.