Thyroid
Every thyroid calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
24 calculators in this section
- ACR TI-RADS Score CalculatorScore a thyroid nodule on the five ACR TI-RADS ultrasound features, with echogenic foci added rather than chosen, and read the TR level against the nodule's size.
- Anti-Thyroglobulin Antibody Unit ConverterConvert thyroglobulin antibody between IU/mL, kIU/L and IU/L — the first two are the same number — and read it for what it mostly is: the companion test that decides whether a thyroglobulin result can be believed.
- Anti-TPO Antibody Unit ConverterIU/mL, kIU/L and U/mL are the same number for thyroid peroxidase antibodies — convert between them, and then note the thing that matters more than any conversion: results from different assays cannot be compared with each other at all.
- Burch-Wartofsky Score Calculator (Thyroid Storm)Score the degree of systemic decompensation in suspected thyroid storm — a clinical diagnosis that biochemistry alone cannot make.
- Free T3 to Reverse T3 Ratio CalculatorDivide free T3 by reverse T3 in matched molar units — and see why the same pair of results gives four different "ratios" depending on the units, and why no cut-off is published here.
- Free Thyroxine (FT4) Unit ConverterConvert free T4 between ng/dL, pmol/L and ng/L, and see why the interval belongs to the assay rather than to the patient.
- Free Thyroxine Index (FTI) CalculatorCorrect total T4 for binding-protein changes using T3 uptake — the historical workaround for a direct free T4 assay.
- Free Triiodothyronine (FT3) Unit ConverterConvert free T3 between pg/mL, pmol/L and ng/L, and see why the commonest low FT3 is non-thyroidal illness rather than hypothyroidism.
- FT3 to FT4 Ratio CalculatorEstimate peripheral T4-to-T3 conversion from free T3 and free T4 — a marker with no validated reference interval.
- Levothyroxine Dose Adjustment from TSH CalculatorAdjust an established levothyroxine dose against the current TSH using the label's 12.5 and 25 µg increments, with the target range for the clinical situation.
- Levothyroxine Dose CalculatorEstimate a starting levothyroxine dose from body weight and clinical situation, from cautious elderly starts to TSH suppression.
- Levothyroxine to Liothyronine Dose ConverterInterpret an existing levothyroxine dose in liothyronine-equivalent terms, using the published but contested potency ratios.
- Myxoedema Coma Diagnostic Score CalculatorScore the six domains of the Popoveniuc diagnostic system for myxoedema coma — thermoregulatory, neurological, gastrointestinal, cardiovascular, metabolic and the precipitating event.
- Radioactive Iodine Uptake (RAIU) InterpreterRAIU is already a percentage, so there is nothing to convert. What there is to do with it is the question the test was invented to answer: in a thyrotoxic patient, is the gland making too much hormone or leaking hormone it already made? High uptake and low uptake separate those two, and they are treated in opposite ways.
- Thyroglobulin Doubling Time CalculatorEstimate the thyroglobulin doubling time in differentiated thyroid cancer surveillance from two values and the interval between them — and see why a falling result is the good one.
- Thyroglobulin Unit Converterng/mL and µg/L are the same number — convert between them, and then read the result the way a thyroglobulin has to be read: as a tumour marker for thyroid cancer follow-up, always alongside the thyroglobulin antibody, and always on one laboratory's assay.
- Thyroid Function in Pregnancy Interpreter (TSH by Trimester)Read a TSH in pregnancy against a trimester-specific interval — your laboratory's, or the fallback the 2026 American Thyroid Association guideline gives when there is none — with the FT4, the trimester and whether it is a first result. It applies the 2026 treatment thresholds, which drop the antibody-based rules of the 2017 guideline, and it handles the levothyroxine target and the suppressed TSH of early pregnancy.
- Thyroid Function Test Interpreter (TSH, FT4, FT3)Enter where the TSH and free T4 fall against your laboratory's reference intervals — and free T3 if measured — with the context that changes the answer: levothyroxine, acute illness, pregnancy, biotin, amiodarone. It names the pattern, including the discordant ones that most pages get wrong: a raised TSH with a raised FT4, a low TSH with a low FT4, and the result that is really a missed dose or a supplement.
- Thyroid Nodule Volume CalculatorCalculate nodule or lobe volume from three ultrasound measurements using the ellipsoid formula, since growth is defined by volume, not diameter.
- Thyroxine-Binding Globulin (TBG) Unit ConverterConvert TBG between mg/L, µg/mL, mg/dL and µg/dL — mg/L and µg/mL are the same number — and see why the one thing this rarely ordered measurement is for is explaining a total T4 that does not match the patient.
- Total Thyroxine (Total T4) Unit ConverterConvert total T4 between µg/dL, µg/L and nmol/L — and read the result knowing that a total thyroxine follows the concentration of the proteins carrying it, which is why pregnancy and the oral contraceptive raise it in patients who are not thyrotoxic.
- Total Triiodothyronine (Total T3) Unit ConverterConvert total T3 between ng/dL, pg/mL, ng/mL and nmol/L — with the factor-of-ten trap between ng/dL and pg/mL, and why a low total T3 in an unwell patient is illness rather than thyroid disease.
- TRAb (TSH Receptor Antibody) Unit ConverterIU/L and U/L are the same number for TRAb, and mIU/L is a thousand times either. Relabelling the number is trivial; the hard part is that TRAb is a polyclonal, functionally mixed antibody population, so two assays reporting the same unit are not reporting the same quantity.
- TSH Unit ConvertermIU/L, µIU/mL and mU/L are the same number for TSH. That is the answer; the rest of this page is the interpretation, which is where TSH is actually difficult.