Immunology, Autoantibodies & Complement
Every immunology, autoantibodies & complement 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.
36 calculators in this section
- 2010 ACR/EULAR Rheumatoid Arthritis Classification Criteria CalculatorScore the four 2010 ACR/EULAR domains out of 10, with the synovitis entry condition enforced rather than assumed — and with what classification criteria are actually for.
- 2019 EULAR/ACR SLE Classification Criteria CalculatorScore the 2019 EULAR/ACR criteria with the ANA entry requirement, the one-criterion-per-domain rule and the attribution rule all enforced, not just described.
- ACR/EULAR Boolean and Index Remission InterpreterAll four ACR/EULAR remission definitions on one patient: the 2011 Boolean criteria, the 2022 revision that moved the patient global from 1 to 2, and the index-based SDAI definition — which classify different patients.
- ACR20, ACR50 and ACR70 Response CalculatorA conjunction, not a score: both joint counts must improve by the stated percentage AND three of the remaining five core-set measures. Improvement in the joints alone is not an ACR response.
- Age-Adjusted ESR Upper Limit CalculatorCalculate the age- and sex-adjusted upper limit of normal for the erythrocyte sedimentation rate using Miller's formula, instead of applying a fixed cut-off of 20 mm/h.
- Alpha-1 Antitrypsin Unit ConverterConvert alpha-1 antitrypsin between mg/dL, g/L, mg/L and µmol/L, with the protective threshold and why an acute-phase rise can hide a deficient patient.
- Alpha-1-Acid Glycoprotein Unit ConverterConvert alpha-1-acid glycoprotein (orosomucoid) between g/L and mg/dL — and use it for what it is actually good for: a correction factor, because it binds basic drugs and a raised level cuts the free fraction at an unchanged total concentration.
- ANA Titre ConverterConvert doubling dilutions past 1:40 into a reciprocal ANA titre, and see when a change actually means something.
- Anti-CCP Antibody Unit ConverterU/mL and kU/L are the same number — convert between them, and then treat the number as meaningless without its method, because anti-CCP units differ between second- and third-generation assays and between manufacturers.
- Antistreptolysin O (ASO) Unit ConverterIU/mL and U/mL are the same number and IU/L is a thousand times larger — so the value of this page is the interpretation, not the arithmetic.
- ASDAS Improvement and Worsening CalculatorThe two ASAS-endorsed change thresholds on one pair of ASDAS values: 1.1 for clinically important improvement, 2.0 for major improvement, and 0.9 in the other direction for clinically important worsening.
- ASDAS-CRP and ASDAS-ESR CalculatorBoth published ASDAS versions on the same four symptom scores, side by side, with the 2 mg/L CRP floor applied and the gap between them shown — the coefficients and the inflammatory term are different and the answers are not interchangeable.
- Beta-2 Microglobulin Unit ConverterConvert beta-2 microglobulin between mg/L, µg/mL and nmol/L, with the ISS myeloma thresholds and why renal function dominates the interpretation.
- CDAI Calculator for Rheumatoid ArthritisThe rheumatology Clinical Disease Activity Index: two joint counts and two global assessments, added with equal weight and no laboratory value at all. Not the Crohn's index of the same abbreviation.
- Coeliac Serology InterpreterInterpret anti-tTG IgA, total IgA and EMA together, and see why a gluten-free diet before testing invalidates the result.
- Complement C3 Unit ConverterConvert complement C3 between g/L, mg/dL and mg/L, and read it the way it should be read — as a pattern with C4, not as a number on its own.
- Complement C4 Unit ConverterConvert complement C4 between g/L, mg/dL and mg/L — and read it the opposite way round to most tests, because complement is consumed when it is activated, so it is a LOW C4 that is the abnormal finding.
- CRP Unit ConverterConvert C-reactive protein between mg/L, mg/dL and µg/mL, and see why the tenfold difference between the two mass units is the trap that matters.
- DAPSA and cDAPSA Calculator for Psoriatic ArthritisSixty-eight tender joints, sixty-six swollen, two patient scales and CRP in mg/dL, with the clinical version computed beside it — and the two have different cut-offs, one point apart at the upper two boundaries.
- DAS28-CRP CalculatorCalculate DAS28-CRP for rheumatoid arthritis disease activity, and see the joints and biases it does not capture.
- DAS28-ESR CalculatorCalculate DAS28-ESR with its four component contributions shown separately, and see exactly how far it diverges from DAS28-CRP in the same patient.
- Eosinophil Cationic Protein Unit ConverterConvert ECP between µg/L, ng/mL and pg/mL — the first two are the same number. The reason this page exists is the sentence under the ladder: eosinophils keep releasing ECP into the tube after the blood is drawn, so a serum ECP without a stated clotting time and temperature cannot be compared with anyone's reference interval, including the one printed beside it.
- EULAR DAS28 Response Criteria InterpreterThe response criteria that need two facts, not one: how much the DAS28 fell AND where it has landed. The same fall of 1.5 is a good response from 4.5 and only a moderate one from 6.5.
- Immunoglobulin A (IgA) Unit ConverterConvert IgA between g/L, mg/dL and mg/L — and check it before you trust a coeliac screen, because IgA deficiency makes tissue transglutaminase IgA uninterpretable.
- Immunoglobulin G (IgG) Unit ConverterConvert IgG between g/L, mg/dL and mg/L, and see why a raised total cannot tell a polyclonal rise from a paraprotein.
- Immunoglobulin M (IgM) Unit ConverterConvert IgM between g/L and mg/dL — and read it knowing the one thing IgM tells you that IgG cannot: a raised specific IgM points to recent infection, while a raised specific IgG points to past exposure or immunity.
- ISS Myeloma Staging CalculatorStage newly diagnosed multiple myeloma from beta-2 microglobulin and albumin, and see how R-ISS builds on it.
- Kappa Free Light Chain Unit Convertermg/L, mg/dL and µg/mL for free kappa light chains — and the point the units conceal, which is that a Freelite result and an N Latex result are different numbers for the same serum and cannot be compared.
- Lambda Free Light Chain Unit Convertermg/L, mg/dL and µg/mL for free lambda light chains — and the point the units conceal, which is that a Freelite result and an N Latex result are different numbers for the same serum and cannot be compared.
- Paraprotein and MGUS Risk Interpreter — Mayo Risk, IMWG LimitsEnter the paraprotein (M-protein) band, its type and the free light chain ratio, with marrow, urine and end-organ findings if you have them. It gives the Mayo MGUS risk group with the published 20-year progression risks, and checks the result against the IMWG 2014 boundaries between MGUS, smouldering myeloma and myeloma — including the SLiM-CRAB myeloma-defining events, IgM paraproteins and light-chain MGUS, to which the Mayo model does not apply.
- Rheumatoid Factor Unit ConverterIU/mL and kIU/L are the same number — convert between them, then read the result honestly: rheumatoid factor is neither necessary nor sufficient for a diagnosis of rheumatoid arthritis, and results are not comparable between assays.
- Serum Free Light Chain Ratio CalculatorCalculate the kappa:lambda free light chain ratio, and see why the normal range shifts in renal impairment.
- Simplified Disease Activity Index (SDAI) CalculatorThe CDAI plus CRP in mg/dL — and mg/dL is where implementations go wrong. Both totals are shown, so the fifth term is visible, and the SDAI is also the ACR/EULAR index-based definition of remission.
- SLEDAI-2K CalculatorScore all 24 SLEDAI-2K descriptors over the preceding 10 days, with organ-system subtotals that show where the 105 available points actually sit.
- Specific IgE Class InterpreterTurn an allergen-specific IgE concentration in kUA/L into its RAST class — and read it as what it is, a concentration band rather than a severity grade.
- Total IgE Unit ConverterConvert total IgE between kU/L, IU/mL and ng/mL, and see why the number is a poor standalone allergy test.