ANA & Autoimmune Serology Pathway

Pre-test probability, ANA-directed serology and ACR/EULAR classification · v2.0
How to use this tool: Four stages, each unlocked by the one before it, in the order the workup is actually done: clinical phenotype and pre-test probability, then the ANA, then only those antibodies the ANA pattern and the phenotype make relevant, then the confirmatory and organ-staging tests. A serological result entered without a clinical context cannot be interpreted, so the pathway does not let you start there.

Stage 1. Clinical Context and Pre-test Probability

Shown for women of reproductive age. It changes the anti-Ro advice and the choice of immunosuppressant.
Tick only what is present and not better explained by something else. The ACR/EULAR criteria call this the attribution rule and it is an overarching principle, not a footnote. An item with a more likely explanation does not count.
This section governs the whole pathway. Every classification criteria set requires that an item is counted only when no more likely explanation exists. In Indian practice the commonest more likely explanation is an infection. Anything ticked here suppresses classification and redirects the output.
The suggestion is derived from the features ticked above and is deliberately conservative. Override it if your clinical judgement differs: this is the input the whole probability calculation rests on.

Antibody Atlas

What each antibody points to, what it is worth, and what it obliges you to do next. The action column is the part that matters: an antibody that does not change management is a laboratory result, not a clinical finding.

1. Nuclear Antibodies of Lupus and Overlap

AntibodyPoints toDiagnostic worthAction it obliges
Anti-dsDNASLE, lupus nephritis6 points in the 2019 criteria, but only on an assay with 90 per cent or better specificity. A screening ELISA does not qualify.Monitor serially. A rising titre with falling C3 and C4 precedes a nephritis flare.
Anti-SmSLE, essentially only SLEThe most specific antibody in the panel. Specificity 99.7 per cent, likelihood ratio around 65, but sensitivity only 17 per cent.Establishes the diagnosis. Do not repeat it: it does not track activity.
Anti-nucleosomeSLESimilar specificity to anti-Sm with more than twice the sensitivity, around 42 per cent. Under-used in Indian laboratories.Worth requesting when SLE is suspected and dsDNA and Sm are negative.
Anti-ribosomal PNeuropsychiatric SLE, lupus hepatitisSpecificity around 99.6 per cent, sensitivity around 32 per cent.In a patient with psychosis, supports a lupus attribution. It does not remove the obligation to exclude CNS infection first.
Anti-histoneDrug-induced lupus, but also idiopathic SLESensitive, not specific. Useless without the drug history.Take a full drug history including isoniazid, hydralazine, phenytoin, minocycline and anti-TNF agents.
Anti-U1 RNPMCTD at high titre, SLE at any titreHigh titre with no SLE-specific antibody suggests MCTD, but clinical features are still required.Baseline echocardiography. Pulmonary arterial hypertension is the leading cause of death in MCTD.
Anti-DFS70Argues against a rheumatic diseaseOnly when monospecific, that is with no other antibody detectable. Present in a few per cent of healthy people.In an otherwise well person with a dense fine speckled ANA, this is the result that lets you stop.

2. Ro, La and the Pregnancy Consequence

AntibodyPoints toDiagnostic worthAction it obliges
Anti-Ro60 (SSA)Sjögren's, SLE, subacute cutaneous lupus3 of the 4 points needed to classify Sjögren's. Cannot classify alone.In a woman planning or carrying a pregnancy, this is the finding that changes obstetric care.
Anti-Ro52 (TRIM21)Myositis, antisynthetase syndrome, interstitial lung disease, autoimmune hepatitisFrequently misreported as a Sjögren's marker. It is not one in isolation.Where the phenotype includes lung disease, treat as a signal to screen the lungs.
Anti-La (SSB)Sjögren's, when accompanying anti-RoAbsent from the 2016 criteria. An isolated anti-La carries little weight.Do not diagnose Sjögren's on an isolated anti-La.
Anti-Ro and pregnancy. Maternal anti-Ro antibodies cross the placenta and can cause neonatal lupus and congenital complete heart block. The risk of heart block in a first pregnancy is of the order of 1 to 2 per cent, rising substantially after a previously affected child. Serial foetal echocardiography through the second trimester is the standard response. This applies to any anti-Ro positive woman, whether or not she has been given a rheumatological diagnosis.

3. Sclerosis Antibodies and What Each Predicts

AntibodyPhenotypePrincipal organ riskAction it obliges
Anti-topoisomerase I (Scl-70)Diffuse cutaneous systemic sclerosisInterstitial lung diseaseBaseline HRCT thorax and pulmonary function tests, then serial monitoring.
AnticentromereLimited cutaneous disease, the CREST phenotypePulmonary arterial hypertension, lateAnnual echocardiography. Lung fibrosis is less likely.
Anti-RNA polymerase IIIRapidly progressive diffuse skin thickeningScleroderma renal crisis; also an association with malignancy around disease onsetDaily home blood pressure monitoring, and age-appropriate cancer screening.
Anti-PM-SclSclerosis and myositis overlapLung and muscleAssess both compartments.
Anti-fibrillarin (U3 RNP)Diffuse disease, often younger patientsPulmonary hypertension, cardiac and renalEchocardiography and cardiac assessment.
Anti-Th/ToLimited diseaseInterstitial lung disease and pulmonary hypertensionDo not be reassured by limited skin involvement. Screen the lungs.
Corticosteroids in systemic sclerosis. Doses above about 15 mg of prednisolone daily are associated with precipitating scleroderma renal crisis, and the risk is greatest in early diffuse disease and in anti-RNA polymerase III positive patients. Where steroids cannot be avoided, use the lowest effective dose and monitor blood pressure and renal function closely.

4. Myositis-specific Antibodies: One Antibody, One Syndrome

AntibodySyndromeWhat it predictsAction it obliges
Anti-Jo-1 and other antisynthetasesAntisynthetase syndrome: myositis, ILD, arthritis, mechanic's hands, Raynaud's, feverInterstitial lung disease dominates the prognosis, and can precede the muscle diseaseHRCT thorax and pulmonary function tests at diagnosis, whatever the CK.
Anti-MDA5Clinically amyopathic dermatomyositis with rapidly progressive ILD; cutaneous ulceration and palmar papulesRapidly progressive, frequently fatal interstitial lung disease. CK is often normal or near normal, which is the point that catches people outUrgent HRCT thorax. Early aggressive combined immunosuppression. Treat as a respiratory emergency, not a dermatological finding.
Anti-TIF1-gammaAdult dermatomyositis with prominent skin diseaseThe strongest malignancy association among the myositis antibodies in adults. In juvenile disease it carries no malignancy associationAge-appropriate and symptom-directed malignancy screening at diagnosis, and repeated over the following three years.
Anti-NXP2Dermatomyositis with calcinosisCalcinosis, severe muscle disease; malignancy association in adultsMalignancy screening in adults. Anticipate calcinosis in juvenile disease.
Anti-Mi-2Classic dermatomyositis with the full rashGood response to treatment, favourable prognosis, low malignancy riskReassure, and treat conventionally.
Anti-SAEDermatomyositis, skin often precedes muscleDysphagia is commonAssess swallowing.
Anti-SRPImmune-mediated necrotising myopathyVery high CK, severe weakness, poor response to corticosteroids alone; cardiac involvement describedEarly escalation beyond steroids: intravenous immunoglobulin or rituximab.
Anti-HMGCRImmune-mediated necrotising myopathy, statin-associatedWeakness that persists or progresses after the statin is stopped. Can also occur without any statin exposureStop the statin, but do not expect that to be enough. Immunosuppression, often with intravenous immunoglobulin, is usually required.
Anti-KuMyositis and sclerosis overlapVariable, often overlap featuresAssess for both.

5. ANCA and Anti-GBM

ResultPoints toCautionsAction it obliges
PR3-ANCAGranulomatosis with polyangiitisAlso positive in cocaine adulterated with levamisole, which produces a strikingly similar destructive nasal pictureAsk about cocaine use before accepting the diagnosis. Exclude tuberculosis before accepting a cavitating lung lesion as GPA.
MPO-ANCAMicroscopic polyangiitis, EGPA, drug-induced vasculitisThe least specific result in the panel. Also seen in inflammatory bowel disease, autoimmune hepatitis, primary sclerosing cholangitis, endocarditis and tuberculosis, and with propylthiouracil, hydralazine and minocyclineA positive MPO-ANCA without a vasculitic syndrome is not a diagnosis and is not an indication to treat.
Immunofluorescence pattern aloneNothing definiteThe 2017 international consensus moved to antigen-specific immunoassay for PR3 and MPO as the primary screen. A c-ANCA or p-ANCA report without antigen specificity is an incomplete resultRequest the antigen-specific assay before acting.
Anti-GBMAnti-glomerular basement membrane diseaseAround a third are also ANCA positive, usually MPO. Double-positive disease behaves like anti-GBM acutely and like ANCA vasculitis in its tendency to relapseA true emergency. Plasma exchange, corticosteroids and cyclophosphamide, without waiting for biopsy where the presentation is fulminant. Test for ANCA in every anti-GBM patient.

6. Antiphospholipid Antibodies

AssayNoteAction it obliges
Lupus anticoagulantThe strongest single predictor of thrombosis of the three. Cannot be interpreted reliably on warfarin, a direct oral anticoagulant, or during acute thrombosisTime the test. If the patient is anticoagulated, say so on the request form and interpret with the laboratory.
Anticardiolipin IgG or IgMOnly medium or high titre counts: above 40 GPL or MPL units, or above the 99th centileA low-titre transient positive after infection is common and should not be classified.
Anti-beta-2 glycoprotein IAbove the 99th centilePart of the triple-positive assessment.
Triple positivityAll three positive carries the highest thrombotic riskWarfarin, not a direct oral anticoagulant. The TRAPS trial found rivaroxaban inferior to warfarin in triple-positive patients, with excess arterial events.
The 12-week rule. Antiphospholipid antibodies must be persistently positive on two or more occasions at least 12 weeks apart before the syndrome can be classified. Transient positivity after infection is frequent. Committing a patient to lifelong anticoagulation on a single positive result is the commonest serious error in this area.

7. What a Negative Panel Does Not Exclude

A module organised around antibodies can imply, by its silence, that a negative panel is reassuring. It is not. The following are substantially or entirely seronegative, and several are more common in Indian practice than the diseases above.

DiseaseHow it is diagnosed instead
Takayasu arteritisImaging of the aorta and its branches: CT or MR angiography. Young Indian women with limb claudication, absent pulses, a blood pressure difference between arms, or unexplained hypertension. No serological marker.
Behçet's diseaseClinical: recurrent oral and genital ulceration, uveitis, pathergy. HLA-B51 supports but does not diagnose.
Axial spondyloarthritisInflammatory back pain, sacroiliac imaging, HLA-B27. ANA and RF are irrelevant.
Adult-onset Still's diseaseQuotidian fever, evanescent rash, arthritis, very high ferritin with a low glycosylated fraction. Diagnosis of exclusion. ANA and RF negative by definition in the classification criteria.
SarcoidosisHistology showing non-caseating granulomas, after tuberculosis has been excluded. In India that exclusion is the whole difficulty.
IgG4-related diseaseHistology with storiform fibrosis and IgG4-positive plasma cells. Serum IgG4 is neither sensitive nor specific enough to stand alone.
Polymyalgia rheumatica and giant cell arteritisClinical, with acute phase response, temporal artery imaging or biopsy.
ANA-negative SLEA small but real group. The 2019 criteria cannot classify them, and the authors say so explicitly. Classification criteria are not diagnostic criteria.

Evidence and the Indian Context

1. Why Pre-test Probability is the Whole Argument

What it is. The probability that the patient has the disease before the test result is known, estimated from the clinical presentation.

Why it matters. In the United States NHANES survey, antinuclear antibodies were present in 13.8 per cent of the population aged 12 and over. Take a hypothetical clinic where 1,000 people are tested and 20 of them have lupus. If the ANA has a sensitivity of 98 per cent and a specificity of 90 per cent, about 20 of the 20 with lupus test positive and about 98 of the 980 without it also test positive. Of 118 positive results, 20 are true. A positive ANA in that setting is wrong about five times out of six. Nothing about the assay changed; only the prior did.

Bedside pearl. The question to ask before ordering an ANA is not "could this be lupus" but "what would I do differently if it came back positive, and what would I do differently if it came back negative". If the answer to both is "nothing", the test is not indicated. Ordering an ANA to reassure a patient with fatigue reliably achieves the opposite.

Indian context. ANA is increasingly ordered from primary care and by direct-to-consumer laboratory packages, often as part of a bundled panel the patient bought without a clinical question attached. A great deal of rheumatology outpatient time in Indian teaching hospitals is now spent unpicking an incidental low-titre ANA in a well person. This module's stage 1 exists to make that prior explicit before the number is looked at.

2. The Great Indian Mimics

Before an autoimmune diagnosis is accepted in India, the endemic mimics must be actively excluded, not merely considered. Empirical corticosteroids given to a patient with disseminated tuberculosis are not a neutral act.
The mimicHow it presentsWhich antibodies it can turn positiveWhat separates them
TuberculosisChronic fever, weight loss, cavitating lung lesions resembling GPA, serositis, Poncet's reactive polyarthritisRF, low-titre ANA, occasionally ANCATissue diagnosis, CBNAAT, culture. A cavitating lesion in India is tuberculosis until proven otherwise.
LeprosyPolyarthritis, neuropathy, skin lesions. Type 2 lepra reaction with erythema nodosum leprosum closely mimics systemic vasculitisANA, RF, sometimes ANCA, and false-positive antiphospholipid antibodiesSlit skin smear, nerve thickening, the distribution of the skin lesions.
Dengue and chikungunyaSevere symmetric polyarthritis, rash, thrombocytopenia. Chikungunya arthritis can persist for months and is regularly mistaken for early rheumatoid arthritisRF, low-titre ANA, transient antiphospholipid antibodiesThe epidemic context, the acute febrile prodrome, and serology for the virus.
Kikuchi-Fujimoto diseaseYoung woman, fever, tender cervical lymphadenopathy, cytopenias. Reproduces an SLE flare closely, and can coexist with SLELow-titre ANALymph node biopsy. There is no serological shortcut.
HIVCytopenias, arthralgia, sicca, vasculitic rash, diffuse infiltrative lymphocytosis syndrome resembling Sjögren'sANA, RF, antiphospholipid antibodiesHIV testing before immunosuppression, without exception.
Hepatitis CCryoglobulinaemic vasculitis, arthralgia, siccaRF strongly positive, ANA, antiphospholipid antibodiesHepatitis C serology and viral load. It is also a formal exclusion in the Sjögren's criteria.
Infective endocarditisFever, glomerulonephritis, splinter haemorrhages, low complement, cytopenias. Reproduces lupus nephritis and ANCA vasculitis togetherANCA, RF, ANA, low C3 and C4Blood cultures before antibiotics, and echocardiography. This is the classic error: a patient given pulse steroids for a presumed pulmonary-renal syndrome who had endocarditis.
IgG4-related diseaseTumefactive masses, pancreatitis, sialadenitis, retroperitoneal fibrosis. Mimics Sjögren's and vasculitisModestly raised serum IgG4; ANA can be positiveHistology showing storiform fibrosis and an IgG4-positive plasma cell infiltrate.

3. Static and Dynamic Markers

Why it matters. Repeating a static marker costs money, delays nothing and answers no question. In a system where the patient is often paying out of pocket, a repeated ENA panel is a real harm.

Static: establish the diagnosis, do not repeat
  • ANA by immunofluorescence, and its pattern
  • Anti-Sm, anti-Ro, anti-La
  • Anti-U1 RNP, anti-Scl-70, anticentromere
  • Myositis-specific antibodies
  • Anti-CCP
Titres do not track disease activity. Once positive, the information has been obtained.
Dynamic: monitor serially
  • Anti-dsDNA titre
  • Complement C3 and C4
  • Urine protein-creatinine ratio and sediment
  • ANCA titre, in selected patients
  • Creatine kinase, in myositis
A rising anti-dsDNA with falling C3 and C4 precedes a lupus nephritis flare and is the pairing worth watching.

4. The ANA Pattern is Half the Test

What it is. The staining pattern on HEp-2 cells, now standardised internationally as ICAP anti-cell (AC) codes.

Why it matters. The pattern predicts which antibodies will be found and, occasionally, tells you to stop looking. A titre reported without a pattern has discarded half of what the test produced.

PatternICAP codeExpectAssociations
HomogeneousAC-1dsDNA, nucleosome, histoneSLE, drug-induced lupus, juvenile idiopathic arthritis
Dense fine speckledAC-2DFS70, and nothing elseArgues against a rheumatic disease when monospecific
CentromereAC-3CENP-A, CENP-BLimited cutaneous systemic sclerosis, primary biliary cholangitis
Fine or coarse speckledAC-4, AC-5Ro, La, Sm, U1 RNPSLE, Sjögren's, MCTD
Nuclear dotsAC-6, AC-7Sp100, PMLPrimary biliary cholangitis
NucleolarAC-8 to AC-10Scl-70, PM-Scl, fibrillarin, Th/To, RNA pol ISystemic sclerosis and overlap
Nuclear envelopeAC-11, AC-12gp210, laminsPrimary biliary cholangitis, autoimmune hepatitis
CytoplasmicAC-15 to AC-21Jo-1, ribosomal P, AMA-M2, SRPMyositis, neuropsychiatric SLE, primary biliary cholangitis

Bedside pearl. A cytoplasmic pattern is frequently reported by laboratories as "ANA negative", because strictly it is not nuclear. In a patient with myositis or unexplained interstitial lung disease that reported negative may be concealing an anti-Jo-1. Read the comment on the report, not only the conclusion.

5. Classification Criteria are Not Diagnostic Criteria

What it is. Classification criteria exist to assemble homogeneous groups for research. They are deliberately weighted towards specificity so that trial cohorts are clean.

Why it matters. The authors of the 2019 SLE criteria state directly that the criteria "should never be used to exclude patients who do not fully meet these criteria from receiving appropriate therapies". A patient scoring 8 who is clinically obvious still has lupus and still needs treating. This module reports the score and says whether the threshold is met; it does not tell you whether to treat.

Bedside pearl. The commonest misuse is the reverse of the one people expect. It is not that criteria are used too loosely; it is that a patient who genuinely has the disease is denied treatment because a score came to 8 rather than 10.

6. Likelihood Ratios and Why This Module Refuses to Multiply Them

What it is. A likelihood ratio converts a pre-test probability into a post-test probability. Post-test odds equal pre-test odds multiplied by the likelihood ratio.

Why it matters. Sequential multiplication of likelihood ratios is only valid when the tests are conditionally independent given the disease state. Autoantibodies are strongly correlated: a patient with anti-Sm is far more likely than chance to also have anti-dsDNA and a high-titre ANA. Multiplying them treats correlated evidence as though it were independent, and the resulting probability can be badly overstated.

What this module does instead. It applies the single strongest likelihood ratio present, names it, and states its source and its limitations on screen. The one composite figure it does use, the likelihood ratio attached to the number of positive autoantibodies, was measured as a composite in the source study and is therefore legitimate to use as a single step.

Provenance of the numbers. The likelihood ratios come from Lin and colleagues, a retrospective study of 1,297 patients tested at a single Chinese tertiary hospital, of whom 148 had SLE. The comparison group is other patients who had the panel sent, not healthy people, so these figures describe a rheumatology referral population. They should not be applied to unselected screening, and no equivalent Indian dataset was available to me. Where the module shows a probability it repeats this caveat.

7. What This Module Does Not Cover

Stated so that the boundary is explicit rather than implied.

  • Organ-specific autoimmunity is out of scope. Autoimmune hepatitis, primary biliary cholangitis, coeliac disease, autoimmune thyroid disease, type 1 diabetes and LADA, myasthenia gravis, AQP4 and MOG antibody disease, autoimmune encephalitis, pemphigus and pemphigoid, and autoimmune gastritis are not evaluated here.
  • The EULAR/ACR 2017 myositis probability is not computed. Those criteria convert a weighted score into a probability through a published regression model whose coefficients could not be verified to the standard this project requires. The module interprets the myositis-specific antibodies instead, and says so on every run.
  • The ACR/EULAR 2023 antiphospholipid criteria are not applied. The module applies the Sydney 2006 criteria, which are verified. The 2023 criteria exist and are more restrictive.
  • Paediatric practice is not covered. The weights and thresholds here are the adult ones.
  • Disease activity indices are not calculated. SLEDAI, BVAS, mRSS and the ESSDAI are separate instruments.
Abbreviations: AC code (ICAP Anti-Cell code) · ACPA (Anti-Citrullinated Protein Antibody) · ACR (American College of Rheumatology) · AMA-M2 (Anti-Mitochondrial Antibody, M2 Subtype) · ANA (Antinuclear Antibody) · ANCA (Antineutrophil Cytoplasmic Antibody) · APS (Antiphospholipid Syndrome) · AQP4 (Aquaporin-4) · ATT (Anti-Tubercular Therapy) · BVAS (Birmingham Vasculitis Activity Score) · C3 (Complement Component 3) · C4 (Complement Component 4) · c-ANCA (Cytoplasmic Antineutrophil Cytoplasmic Antibody) · CBNAAT (Cartridge-Based Nucleic Acid Amplification Test) · CCP (Cyclic Citrullinated Peptide) · CD4 (Cluster of Differentiation 4) · CENP-A / CENP-B (Centromere Protein A / Centromere Protein B) · CK (Creatine Kinase) · CLIA (Chemiluminescence Immunoassay) · CNS (Central Nervous System) · CRP (C-Reactive Protein) · CSF (Cerebrospinal Fluid) · CT (Computed Tomography) · DFS70 (Dense Fine Speckled 70 kDa) · DMARD (Disease-Modifying Antirheumatic Drug) · dsDNA (Double-stranded DNA) · EGPA (Eosinophilic Granulomatosis with Polyangiitis) · ELISA (Enzyme-Linked Immunosorbent Assay) · ENA (Extractable Nuclear Antigen) · ENT (Ear, Nose and Throat) · ESR (Erythrocyte Sedimentation Rate) · ESSDAI (EULAR Sjögren's Syndrome Disease Activity Index) · EULAR (European Alliance of Associations for Rheumatology) · GBM (Glomerular Basement Membrane) · gp210 (Glycoprotein 210 kDa) · GPA (Granulomatosis with Polyangiitis) · HEp-2 (Human Epithelial Type 2 Cell Line) · HIV (Human Immunodeficiency Virus) · HLA (Human Leucocyte Antigen) · HMGCR (3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase) · HRCT (High Resolution Computed Tomography) · ICAP (International Consensus on ANA Patterns) · IFA (Immunofluorescence Assay) · IgG (Immunoglobulin G) · IgG4 (Immunoglobulin G4) · IgM (Immunoglobulin M) · IIM (Idiopathic Inflammatory Myopathy) · ILD (Interstitial Lung Disease) · ISN/RPS (International Society of Nephrology / Renal Pathology Society) · ISTH (International Society on Thrombosis and Haemostasis) · Jo-1 (Histidyl-tRNA Synthetase) · LADA (Latent Autoimmune Diabetes in Adults) · LDH (Lactate Dehydrogenase) · LR (Likelihood Ratio) · MCP (Metacarpophalangeal) · MCTD (Mixed Connective Tissue Disease) · MDA5 (Melanoma Differentiation-Associated Gene 5) · MOG (Myelin Oligodendrocyte Glycoprotein) · MPA (Microscopic Polyangiitis) · MPO (Myeloperoxidase) · MR (Magnetic Resonance) · MRI (Magnetic Resonance Imaging) · mRSS (Modified Rodnan Skin Score) · MSA (Myositis-Specific Antibody) · NHANES (National Health and Nutrition Examination Survey) · NXP2 (Nuclear Matrix Protein 2) · OSS (Ocular Staining Score) · PAH (Pulmonary Arterial Hypertension) · p-ANCA (Perinuclear Antineutrophil Cytoplasmic Antibody) · PIP (Proximal Interphalangeal) · PL-12 (Alanyl-tRNA Synthetase) · PL-7 (Threonyl-tRNA Synthetase) · PML (Promyelocytic Leukaemia Protein) · PM-Scl (Polymyositis-Scleroderma) · PR3 (Proteinase 3) · RA (Rheumatoid Arthritis) · RF (Rheumatoid Factor) · RNA (Ribonucleic Acid) · RNP (Ribonucleoprotein) · SAE (Small Ubiquitin-like Modifier Activating Enzyme) · Scl-70 (Scleroderma 70 kDa Antigen, Topoisomerase I) · SLE (Systemic Lupus Erythematosus) · SLEDAI (Systemic Lupus Erythematosus Disease Activity Index) · Sp100 (Speckled 100 kDa Protein) · SRP (Signal Recognition Particle) · SSA (Sjögren's Syndrome-Related Antigen A) · SSB (Sjögren's Syndrome-Related Antigen B) · SSc (Systemic Sclerosis) · TIF1-gamma (Transcriptional Intermediary Factor 1 Gamma) · TNF (Tumour Necrosis Factor) · TRIM21 (Tripartite Motif-containing Protein 21) · UACR (Urine Albumin-to-Creatinine Ratio) · UPCR (Urine Protein-to-Creatinine Ratio)
Algorithm References & Evidence Base
  1. Aringer M, Costenbader K, Daikh D, et al. 2019 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Systemic Lupus Erythematosus. Arthritis Rheumatol. 2019;71(9):1400-1412.
  2. van den Hoogen F, Khanna D, Fransen J, et al. 2013 classification criteria for systemic sclerosis: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Ann Rheum Dis. 2013;72(11):1747-1755.
  3. Shiboski CH, Shiboski SC, Seror R, et al. 2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary Sjogren's syndrome. Ann Rheum Dis. 2017;76(1):9-16.
  4. Robson JC, Grayson PC, Ponte C, et al. 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for granulomatosis with polyangiitis. Ann Rheum Dis. 2022;81(3):315-320.
  5. Suppiah R, Robson JC, Grayson PC, et al. 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for microscopic polyangiitis. Ann Rheum Dis. 2022;81(3):321-326.
  6. Grayson PC, Ponte C, Suppiah R, et al. 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for eosinophilic granulomatosis with polyangiitis. Ann Rheum Dis. 2022;81(3):309-314.
  7. Aletaha D, Neogi T, Silman AJ, et al. 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010;62(9):2569-2581.
  8. Miyakis S, Lockshin MD, Atsumi T, et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost. 2006;4(2):295-306.
  9. Satoh M, Chan EKL, Ho LA, et al. Prevalence and sociodemographic correlates of antinuclear antibodies in the United States. Arthritis Rheum. 2012;64(7):2319-2327.
  10. Lin S, Zhang Y, Chen L, et al. High titers of antinuclear antibody and the presence of multiple autoantibodies are highly suggestive of systemic lupus erythematosus. Sci Rep. 2022;12(1):1687.
  11. Lundberg IE, Tjarnlund A, Bottai M, et al. 2017 European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis. 2017;76(12):1955-1964.
  12. Misra DP, Sharma A, Dharmanand BG, Chandrashekara S. The Epidemiology of Rheumatic Diseases in India. Indian J Rheumatol. 2024;19(Suppl 1).
  13. Indian Rheumatology Association guidelines for the management of ANCA associated vasculitis. Indian J Rheumatol. 2024.
How to Cite This Tool

AMA Style:
Umakanth S. ANA & Autoimmune Serology Pathway. MEDiscuss. Published 2026. Accessed .

Vancouver Style:
Umakanth S. ANA & Autoimmune Serology Pathway [Internet]. MEDiscuss.org; 2026 [cited ]. Available from:

Category Advanced DiagnosticsPathway
Specialties Immunology, Internal Medicine, Rheumatology, Nephrology
Status Essential
Revision date not recorded for this module. Please verify dosing and thresholds against current guidance before use.