A patient in her early thirties arrives at her primary care provider with vague, unexplained symptoms: joint pain that is not confined to one joint but spread throughout her body, fatigue out of proportion to her usual level of activity, and intermittent rashes that have come and gone. Any one of those complaints has a long list of possible causes, and even when considered together, they may still point to a broad range of potential diagnoses.

What happens to patients like this over the next several years of their diagnostic journey is well documented. In a survey of 233 patients with lupus and related systemic autoimmune rheumatic diseases, the mean time from first symptom to diagnosis was just under seven years, and 76% reported at least one misdiagnosis before their symptoms were correctly attributed.¹ The delay rarely comes from one test or one clinical encounter; it accumulates across the diagnostic journey.

Patients with systemic autoimmune connective tissue diseases often present with symptoms that overlap across multiple autoimmune and non-autoimmune conditions, which makes it difficult to determine which disease-specific laboratory tests should be ordered initially. The diagnostic process may involve multiple rounds of laboratory testing and consultations with different clinicians before a clearer clinical picture emerges.

Each of those rounds is a point where the laboratory can influence the diagnostic pathway. Through test selection, reflex algorithms, interpretive reporting and diagnostic stewardship, laboratories can help turn what might otherwise be a series of disconnected test orders into a more deliberate pathway toward diagnosis. The challenge is not simply to make more testing available, but to provide testing options that allow laboratories to build strategies appropriate for the patient populations and clinical settings they serve.

Why connective tissue disease resists a single diagnostic answer

Systemic autoimmune connective tissue disease covers conditions including systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, idiopathic inflammatory myopathies, and mixed connective tissue disease, and although these conditions differ in organ involvement, treatment, and prognosis, they are hard to distinguish when a patient first presents.Symptoms such as fatigue, joint pain, stiffness and rash overlap across multiple autoimmune and non-autoimmune diseases.² Misdiagnosis with another condition is therefore not surprising. Lupus, for example, may initially be confused with rheumatoid arthritis, fibromyalgia, thyroid disease and other disorders that share similarities in clinical presentation.

Traditionally, connective tissue disease testing has followed a stepwise approach, beginning with an antinuclear antibody (ANA) screening test and if positive moving to individual autoantibody tests to help narrow the differential diagnosis or potentially support the diagnosis of a specific disease. While no single laboratory result alone establishes the diagnosis of these diseases, appropriately selected, disease-relevant serologic testing is a critical component of the diagnostic evaluation. The laboratory therefore plays an important role not simply in generating results, but in helping ensure that the right tests are selected, sequenced, and interpreted alongside clinical findings to inform the final clinical judgement.

This distinction matters because there is no single testing strategy that is optimal for every clinical setting. The appropriate approach may depend on disease prevalence, patient demographics, referral patterns, clinician experience, testing volume, and the laboratory's existing workflow and instrumentation. The goal should be to give laboratories sufficient testing options to design pathways that meet the needs of the populations they serve.

Where the diagnostic path stalls

Access to rheumatology remains an important challenge. The American College of Rheumatology's workforce study estimated 6,000 adult rheumatology providers—including physicians, nurse practitioners and physician assistants—in 2015 and projected that demand could substantially exceed supply by 2030. For many patients, primary care therefore remains an important entry point into the diagnostic pathway.

When specialist access is limited, the diagnostic pathway that precedes referral becomes an important part of access to care itself. Primary care clinicians must evaluate patients across an extraordinarily broad range of diseases, while the early manifestations of systemic autoimmune conditions may be subtle, nonspecific or evolve over time. A well-designed laboratory pathway can provide more actionable information earlier in that process, helping clinicians determine which patients warrant additional autoimmune evaluation or specialist referral. In this way, the laboratory can help patients move more efficiently through a constrained healthcare system and support more appropriate use of limited specialist resources.

Symptoms also get attributed elsewhere along the way, and those attributions follow a pattern. Autoimmune conditions affect more women than men, so when women present symptoms such as fatigue, pain, or changes in well-being, they can often be attributed to stress, mood, or hormonal factors. In the survey mentioned above, 47% of reported misdiagnoses were categorized as mental health conditions or medically unexplained symptoms.¹ About nine in ten people with lupus are women, according to the Lupus Foundation of America, so this happens to the central patient population rather than at the margins.³

Stress, mood and hormonal change are legitimate possibilities and may sometimes contribute to a patient's symptoms. The problem comes when one of them is accepted as the whole answer resulting in premature diagnostic closure despite persistent, evolving, or multisystem features that warrant further evaluation.

Seronegativity compounds diagnostic ambiguity. In the same survey, respondents reporting persistently negative ANA experienced substantially longer diagnostic delays than those reporting positive ANA. Although the seronegative subgroup was small and the study relied on patient-reported results, the finding illustrates an important limitation of relying too heavily on a single negative serologic result: negative testing may lower the probability of a specific disease, but it does not always end the diagnostic evaluation.

Ordering patterns stall things too. In a review of ANA and ENA ordering across 58,627 patients, extractable nuclear antigen (ENA) testing was ordered without any ANA in 24.2% of cases and alongside the ANA in another 8.3%.⁴ Where the ANA came back negative, only a small proportion (2%) had positive ENA results, and an even smaller proportion (0.37%) were subsequently diagnosed with an autoimmune connective tissue disease. The authors estimated that avoiding simultaneous ordering alone would have saved about $2.3 million in costs associated with simultaneous or non-sequential ANA and ENA ordering across roughly 20,000 patients.

These delays don’t reflect a limitation of the diagnostic tests themselves. The delay comes from how testing is deployed in front-line settings, i.e., selected, sequenced and interpreted, and that is an area where the laboratory can have meaningful influence.

Designing a front-line CTD testing pathway

The question for laboratories is therefore not whether there is one universally correct way to screen for connective tissue disease. It is whether they have enough clinically appropriate testing options to build a pathway that fits their patient population.

For some laboratories and patient populations, ANA by indirect immunofluorescence (ANA-IIF) may remain the preferred front-line approach. ANA-IIF has an important and well-established role in autoimmune diagnostics and is highly sensitive for conditions such as SLE. However, ANA positivity is not specific for systemic autoimmune disease. In a U.S. population, ANA positivity was estimated at 16.1% in 2011–2012, compared with 11.0% approximately two decades earlier. In lower-prevalence populations, such background positivity can result in additional testing and referrals in patients who ultimately do not have a systemic autoimmune connective tissue disease.

Other laboratories may benefit from incorporating defined solid-phase screening approaches, either as an alternative front-line strategy in selected populations or in combination with ANA-IIF. The objective should not be indiscriminately to increase the number of antibodies tested or reported. Rather, screening should be clinically curated, balancing sensitivity and specificity while providing a clear pathway to appropriate follow-up testing.

This is where laboratory choice becomes particularly important. A laboratory serving a rheumatology-heavy population may have different testing needs from one supporting a health system in which most CTD evaluations originate in primary care. Likewise, a laboratory with established ANA-IIF expertise may construct a different pathway from one seeking a more automated front-line approach. Testing strategies should reflect these differences rather than forcing every laboratory and ultimately every clinician into the same algorithm.

The laboratory is uniquely positioned to make these decisions because it can see testing patterns across an entire health system: which tests clinicians order, where repeat testing occurs, where reflex pathways stop, and where results generate additional downstream testing. That perspective creates an opportunity to move from a transactional model of performing requested tests toward a diagnostic stewardship model focused on providing the right information at the right point in the patient's journey.

New testing options can expand the ways laboratories construct these pathways. A recently introduced assay provides one such option.⁵ The assay is designed for the qualitative detection of IgG antibodies against 13 clinically relevant CTD autoantibody specificities and is intended as an aid in the diagnosis of systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, polymyositis, dermatomyositis and mixed connective tissue disease when used in conjunction with other laboratory and clinical findings.

Rather than reporting 13 individual antibody results from the initial screen, the EliA CTD 13 Screen provides a screening result that can be incorporated into a laboratory-defined testing pathway, with appropriate follow-up testing used to identify individual antibody specificities when indicated. This allows laboratories to consider a broader set of clinically relevant autoantibodies at the screening stage while maintaining a structured approach to subsequent testing. On certain platforms, it can be added to an existing autoimmune and allergy test menu rather than requiring another instrument.⁶

This does not mean replacing ANA-IIF or every existing testing algorithm. The methods can serve different and potentially complementary roles. The appropriate approach depends on the population being tested, the clinical question and the laboratory's workflow. In some settings, solid-phase CTD screening may be used alongside ANA-IIF; in others, laboratories may determine that a defined solid-phase screen is useful earlier in the pathway. The important point is that laboratories have options and the ability to apply them deliberately.

Laboratory testing is only one component of diagnosis, but the laboratory has influence far beyond the analytical result itself. By selecting appropriate technologies, designing reflex pathways, supporting result interpretation and continually evaluating how testing performs in the populations they serve, laboratories can help clinicians receive more relevant information earlier in the diagnostic process.

For the patient in her early thirties, the goal is not simply more testing. It is a testing pathway designed to produce the right information at the right time—helping her reach the appropriate specialist with a clearer clinical and laboratory picture and fewer unnecessary steps along an already complex diagnostic journey.

REFERENCES

1. Sloan M, Harwood R, Sutton S, et al. Medically explained symptoms: a mixed methods study of diagnostic, symptom and support experiences of patients with lupus and related systemic autoimmune diseases. Rheumatol Adv Pract. 2020;4(1):rkaa006. doi:10.1093/rap/rkaa006.
2. Connective tissue disease: Types, symptoms & treatments. Cleveland Clinic. April 6, 2017. Accessed October 6, 2026. https://my.clevelandclinic.org/health/diseases/14803-connective-tissue-diseases.
3. Lupus facts and statistics. Lupus Foundation of America. Accessed October 7, 2026. https://www.lupus.org/resources/lupus-facts-and-statistics.
4. Ethington E, Melrose E, Stratman EJ. The relative timing, outcomes, and economic impact of anti-nuclear antibody (ANA) and extractable nuclear antigen (ENA) laboratory ordering. Clin Med Res. 2024;22(3):123-126. doi:10.3121/cmr.2024.1937.
5. Connective tissue disease laboratory testing. Thermo Fisher Scientific. Accessed October 7, 2026. https://www.thermofisher.com/phadia/us/en/our-solutions/elia-autoimmunity-solutions/connective-tissue-diseases.html.
6. Phadia Laboratory Systems. Thermo Fisher Scientific. Accessed October 7, 2026. https://www.thermofisher.com/phadia/us/en/our-solutions/phadia-laboratory-systems.html.