Sjogren's disease and blood tests

What the research found.

• One study screened 64045 people with no history of connective tissue disease. Anti-SSA was positive in 1.7 percent, at 0.9 percent of men and 2.7 percent of women. Of 381 positive people followed for a median of 4.6 years, 146 developed a connective tissue disease and 235 did not.

  Jia and colleagues, Clinical and Experimental Immunology, 2024

• In the screening study above, 68 of the 381 people developed primary Sjogren's disease, which works out at 17.8 percent. Ten of them developed rheumatoid arthritis, at 2.6 percent. Five developed lupus, at 1.3 percent, so most of those who fell ill developed Sjogren's rather than anything else.

  Jia and colleagues, Clinical and Experimental Immunology, 2024

• One study tested 825 healthy blood donors, and at least one antinuclear antibody test was positive in 130 of them. That's 15.8 percent, and of those 130 only 37 accepted a clinical assessment. Two women were diagnosed with Sjogren's disease, and over five years only two of the whole 825 got a rheumatic diagnosis.

  Andraos and colleagues, Frontiers in Medicine, 2024

• One triage study followed 263 people referred to rheumatology for a positive antinuclear antibody. Only 24 percent of them had an antibody-associated rheumatic disease, and Sjogren's accounted for 9.1 percent of the group, or 24 people. Another 26.2 percent had no evidence of any disease at all.

  Fitch-Rogalsky and colleagues, PLOS ONE, 2014

• One study looked at the nailfold vessels of 759 people with Raynaud's. A scleroderma pattern was present in 33 percent of those with primary Sjogren's syndrome. It was present in 88 percent of those with systemic sclerosis and 13 percent of those with rheumatoid arthritis.

  Van Roon and colleagues, The Journal of Rheumatology, 2019

What the number means.

What a positive antibody means when you feel well

Most pages about blood tests describe what happens after somebody is already ill. This one starts earlier, with a study that followed people who tested positive and had no disease at all. It screened 64045 people attending routine health checks, and not one of them had any history of connective tissue disease at the time.

It measured anti-SSA, which is the antibody most associated with Sjogren's disease. Anti-SSA was positive in 1.7 percent of them, at 0.9 percent of the men and 2.7 percent of the women. So roughly one person in sixty had it and felt perfectly well.

Then the study did the useful part, which is the reason this page exists. It followed 381 of those positive people for a median of 4.6 years and recorded what had happened to each of them. That's a design hardly anybody runs, because it means waiting years for an answer.

What happened to those 381 people

Of the 381 people they followed, 146 went on to develop a connective tissue disease, which works out at 38.3 percent. The other 235 of them developed nothing at all. That's 61.7 percent, and it's the majority of the group by a clear margin, which is the half of the result people tend to forget.

The breakdown is worth having, because those diseases weren't spread evenly across the group. Primary Sjogren's disease accounted for 68 of them, which is 17.8 percent of the whole 381. Rheumatoid arthritis accounted for 10 of them, at 2.6 percent, and lupus for another 5, at 1.3 percent.

So two things are true at once here, and both of them need saying together. A positive antibody in a well person is a real signal, because nearly four in ten of them went on to develop something. It also isn't a diagnosis, because six in ten of them developed nothing over the whole follow-up.

One limit is under all of that, and it's the median follow-up of only 4.6 years. Somebody in their thirties is asking about the next fifty years. A study under five years cannot answer a question on that scale, and no study anywhere on this page can. That's worth saying once and saying it plainly.

The two ways to get this wrong

The first mistake is to read 38.3 percent and conclude that a diagnosis is coming for you. It isn't coming for most people in that study, because nearly two thirds of them stayed well through the whole follow-up. That's worth holding onto in the days just after a result arrives.

The second mistake is to read 61.7 percent and dismiss the result altogether. That doesn't work either, because a 38.3 percent rate over less than five years is a substantial risk by any standard. Both errors come from taking one of the two numbers and leaving the other one behind.

The honest position is in the middle, and it's a good deal less satisfying than either end of it. The result is worth taking seriously and it's worth telling your team about. It isn't worth treating as a verdict, because a verdict is a great deal more than these numbers can support.

The broader antibody test is very common

Anti-SSA is one specific antibody, and the antinuclear antibody test is a great deal broader than it. It turns up positive far more often than most people realize. That difference is the whole of what this section is about, and it changes what a result is worth. Two people can be told they have a positive antibody and be in entirely different situations.

One study tested 825 healthy blood donors, and at least one antinuclear antibody test came back positive in 130 of them. That's 15.8 percent, or roughly one healthy person in six. Of those 130, only 37 accepted a clinical assessment, and two women were diagnosed with Sjogren's disease.

Over five years of follow-up, only two of the whole 825 donors received a rheumatic diagnosis from a rheumatologist. That sentence is the strongest argument against screening healthy people with this test. A result that turns up in one person in six and leads to a diagnosis in one in four hundred isn't a useful screen.

One caveat belongs alongside that, because only 37 of the 130 positive donors accepted an assessment. So the two Sjogren's diagnoses come from a self-selected quarter of the positives rather than from all 130 of them. That cuts both ways, and the study reports it plainly rather than burying it.

What the test does when you have symptoms

That same test means something quite different when it's ordered because of symptoms. One study looked at that very situation, following 263 people who had been referred to rheumatology for a positive antinuclear antibody. The referral itself changes what the result is worth, and it changes it a great deal.

Of those 263 people, 24 percent had an antibody-associated rheumatic disease. Sjogren's accounted for 9.1 percent of them, which is 24 people, and lupus accounted for another 9.1 percent. Systemic sclerosis accounted for 2.3 percent, which is a much smaller share. Those three together are the antibody-associated group, and they come to less than a quarter.

The rest is the part worth knowing about, and it's larger than the part above. Another 38.8 percent had a different rheumatic diagnosis, and 26.2 percent had no evidence of any disease at all. So more than a quarter of the people sent on to a specialist turned out to have nothing wrong at all.

Even among people referred on to a specialist, three quarters turned out to have something else or nothing. The test is a starting point there rather than an answer. It narrows the question and it doesn't close it, which is a real contribution and a limited one. Reading it as an answer is what sends people looking for a diagnosis that isn't there.

The nailfold scan

One study looked at the nailfold vessels of 759 consecutive people who had Raynaud's phenomenon. It sorted every result into one of three groups, and those were normal, nonspecific, and showing what's called a scleroderma pattern. That last group is the one people ask about, and it's the one worth being careful with.

That scleroderma pattern was present in 33 percent of the people who had primary Sjogren's syndrome. It wasn't unique to them by any distance at all. It was also present in 88 percent with systemic sclerosis, 71 percent with mixed connective tissue disease, 17 percent with lupus, and 13 percent with rheumatoid arthritis.

So this finding turns up right across the family of connective tissue diseases rather than pointing at one. The study's useful figure was what a normal result rules out. That figure rested on the systemic sclerosis patients rather than on the Sjogren's ones, which is worth knowing. A scan like this narrows things rather than settling them.

What this page can't tell you

Two important tests are missing from this page, and the reason for both is identical. This site holds no source on either one. So no figure appears for either, and neither will until a reference arrives.

The first is measurement of what your eyes and mouth produce, which gets done routinely in practice. Tear production and saliva flow are both part of how this diagnosis gets made, and nothing in our set describes how either performs. That is the biggest hole anywhere on this page.

The second is the lip biopsy, along with the focus score that comes out of it. That's the other half of the standard work-up for this disease, and this site holds nothing on it either. A page that described either without a source would be writing from memory rather than from a paper, and that's the one thing this site won't do.

Both absences are recorded for the physician review rather than hidden. A visible hole is more use to you than a confident sentence with nothing behind it, which is the principle this site runs on. So what's missing is named and the review notes hold the request for references.

What to do with a result you already have

If you've been told an antibody came back positive, the useful questions are short ones. Ask which antibody it was, because anti-SSA and a broad antinuclear antibody are different tests with different meanings, and people confuse the two constantly. That single question narrows a great deal of the worry that comes with a result like this.

Then ask why the test was ordered in the first place. A result found during a screen appears in one situation, and an identical result in somebody with dry eyes and dry mouth appears in quite another. The two questions between them tell you most of what a result is worth.

Then tell your team about symptoms as and when they appear. Don't save them for the next routine appointment, because the wait between visits is where a diagnosis gets delayed. New dryness, new joint pain, and a new rash are the things that screening study was watching for.

Nothing on this page tells you what your own result means for you specifically. It tells you what happened to large groups of people who had the same result, which is a different question altogether. Your team answers the first one, alongside everything else they know about you.

Common misconceptions.

Cautions specific to this condition.

• Take a positive antibody found on screening to your team, not to the internet. In one study, 38.3 percent of positive people developed something over about five years and 61.7 percent didn't.
• Ask why a test was ordered before asking what the result means. A positive antinuclear antibody in a person with symptoms is one thing. The same result in a blood donor is another.
• Don't read a five-year follow-up as a lifetime answer. That's the longest window any study here reports.
• Mention new dryness, new joint pain, or a new rash if you've had a positive antibody. Those are the reasons the follow-up in that study existed.
• This page gives no titer, no threshold, and no reference range. Laboratories differ and what your number means is your team's call.
• No test on this page measures how much tear or saliva you produce. That's a real hole and it's recorded in the review notes.

Questions patients ask.