Can Celiac Blood Tests Show Whether You're Completely Gluten-Free?

Lots of people get tested after they've gone gluten-free

celiac disease blood test
Andrew Brookes / Getty Images

Your doctor probably used celiac blood tests as part of your overall celiac disease testing. Many doctors (and some in the celiac disease community, as well) also believe it's possible to use those same blood tests to monitor how well you're following the gluten-free diet,

Unfortunately, this only works well in cases where you're actually getting a huge amount of gluten in your diet on a regular basis. Otherwise, the tests may falsely say that you're fine (e.g., you're not ingesting much gluten), when in fact you are consuming gluten, potentially at levels that could damage your body.

Here are the facts on this commonly-misunderstood test, and the best ways to use it once you've been diagnosed.

What Celiac Blood Tests Reveal

Blood tests can identify people who regularly cheat on the gluten-free diet, or people who don't understand the many places gluten can hide, and who therefore inadvertently wind up consuming lots of gluten on a regular basis.

But blood tests are unlikely to show when you're still getting small amounts of gluten. Several medical studies indicate that people who have occasional gluten-free diet lapses—even lapses that lead to uncomfortable symptoms—will still likely have negative blood tests despite those lapses.

For example, in one study designed to determine a "safe" threshold for trace gluten exposure, 26 people with confirmed celiac disease received either 10mg or 50mg of gluten each day for 90 days. Some of the people had symptoms, but none had positive celiac blood tests following this gluten challenge, leading the researchers to conclude that the blood tests aren't sensitive enough to detect these trace levels of gluten cross-contamination.

Another study used much higher doses of daily gluten: up to 5 grams (or about one-quarter of a slice of gluten-based bread). In that study, which included 21 people with celiac disease who consumed the gluten for about three months, two-thirds of the subjects had gluten-induced intestinal damage, but only nine had positive celiac blood tests following their gluten challenges.

Nonetheless, 15 of the 21 people in the study reported mild to moderate gastrointestinal symptoms during the study.

Finally, a third study included eight people with celiac disease who consumed up to 10 grams of gluten per day (or half a slice of gluten-based bread) for three weeks. None showed any change in their blood test results, even though six of the eight had diarrhea by day 15 of the study.

Blood Tests Won't Show If You've Healed

Other studies show that negative blood test results don't necessarily mean your intestinal villi have recovered, either.

For example, in one study conducted in Northern Ireland, researchers used the celiac blood test EMA-IgA—considered the most specific test to identify the villous atrophy that characterizes celiac disease—to monitor patients.

Of 53 people who initially had a positive EMA-IgA test, 87% had negative EMA-IgA results after one year following the gluten-free diet. However, 32 of those people still had some villous atrophy after their first year on the diet.

A Word from Verywell

You might be wondering why you should undergo repeat celiac disease blood tests once you've been diagnosed and are following the gluten-free diet.

Here's one reason: repeat blood tests can indicate when a person is virtually ignoring the gluten-free diet, which can help physicians identify people who may need a little extra help (or encouragement). In the study from Northern Ireland, four of the five people who still had positive EMA-IgA test results one year after diagnosis had what the researchers termed "poor dietary compliance."

In addition, repeat blood tests can help monitor your progress on the diet in the first year or so following diagnosis; the blood test numbers should be trending steadily lower, even if they don't reach the negative range right away. Your doctor may want to test you to confirm that steady decline is occurring.

But if you've been following a strict diet for years, repeat blood tests most likely won't give you any additional information on how you're doing. If you're concerned (or if you continue to have symptoms), you might want to ask your doctor for a referral to a dietician who's skilled in trouble-shooting the gluten-free diet.

Was this page helpful?
Article Sources