To understand a patient’s functional thyroid status, traditional “bell curve” ranges can be too broad to be clinically useful:

A common traditional laboratory range for TSH on serum testing is 0.45 – 4.5. A more clinically useful functional range might be:

A common traditional laboratory range for Free T4 on serum testing is 0.82 – 1.77. A more clinically useful functional range might be:

A common traditional laboratory range for Free T3 on serum testing is 2.0 – 4.4. A more clinically useful functional range might be:

A patient has a TSH of 6, a Free T4 of 0.7 (rr 0.82 – 1.77) and a Free T3 of 2.2 (2.0 – 4.4). She is clearly:

A patient has a TSH of 2.9, a Free T4 of 0.95 (rr 0.82 – 1.77) and a Free T3 of 2.7 (2.0 – 4.4). She likely is functionally:

A patient has a TSH of 2.9, a Free T4 of 0.95 (rr 0.82 – 1.77) and a Free T3 of 1.75 (2.0 – 4.4). She likely is functionally:

This same patient as in the previous question, with a TSH of 2.9, a Free T4 of 0.95 (rr 0.82 – 1.77) and a Free T3 of 1.75 (2.0 – 4.4):

A patient has a TSH of 0.005, a Free T4 of 1.85 (rr 0.82 – 1.77) and a Free T3 of 4.5 (2.0 – 4.4). She is functionally:

This same patient as in previous question with a TSH of 0.005, a Free T4 of 1.85 (rr 0.82 – 1.77) and a Free T3 of 4.5 (2.0 – 4.4) :