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Thyroid Function Interpretation Calculator

Work out thyroid function interpretation instantly with clear inputs, formula shown and shareable results.

About Thyroid Function Interpretation Calculator

Combines the TSH value with the position of free T4 in its reference range to name the standard thyroid function pattern.

Formula

Thyroid patterns

High TSH with low free T4 = primary hypothyroidism; high TSH with normal T4 = subclinical hypothyroidism; low TSH with high T4 = hyperthyroidism; low TSH with low T4 suggests central causes

Worked example

With the default values below, Thyroid Function Interpretation Calculator returns Biochemical pattern of Subclinical hypothyroidism. Change any input above and every figure here is recalculated in your browser.

Inputs used

TSHaccepts 0.001–100 mIU/L
6.2 mIU/L
Free T4 relative to the reference rangeone of Below range, Within range, Above range
Within range

Results

Biochemical pattern
Subclinical hypothyroidism
TSH band
Above the usual 0.4-4.0 mIU/L range
Next step
Repeat in 6 to 12 weeks with thyroid antibodies before treating

Step by step

  1. 1Values used
  2. 2Thyroid patterns
  3. 3Biochemical pattern= Subclinical hypothyroidism
  4. 4TSH band= Above the usual 0.4-4.0 mIU/L range
  5. 5Next step= Repeat in 6 to 12 weeks with thyroid antibodies before treating

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Why is the reference range for TSH debated?

The upper limit varies with age, iodine status and assay; many laboratories use 4.0 to 4.5 mIU/L.

Should T3 be measured?

Free T3 adds value mainly in suspected hyperthyroidism or when T4 and TSH are discordant.

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