🦋 Thyroid Function Test Interpretation
Interpret common TSH/FT4/FT3 combinations — primary, subclinical, central and sick-euthyroid disease, with pregnancy caveats. Browser-side reference.
Thyroid Function Test Interpretation
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When to use
Read thyroid function by combination, starting with TSH then FT4. Avoid testing in critical illness.
How it works
TSH ↑ FT4 ↓ primary hypothyroid; TSH ↑ FT4 normal subclinical; TSH ↓ FT4/FT3 ↑ hyperthyroid; TSH ↓ FT4 ↓ central/sick-euthyroid.
Key points
- Read TSH first, then the FT4 combination.
- Follow central disease by FT4, not TSH.
- Sick-euthyroid (low-T3) is easily misread in critical illness.
- Use trimester-specific reference ranges in pregnancy.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.