According to Gram Research analysis, three common laboratory methods for measuring blood folate, microbiological testing, LC-MS/MS, and Tosoh immunoassay, all produce accurate and reliable results with excellent consistency. A 2026 study of 58 blood samples found that all three methods showed variation of 7% or less when testing the same sample multiple times, and all demonstrated good accuracy against reference standards. The methods showed only small differences in results, with the Tosoh immunoassay reading 3-4 nmol/L higher than the other two methods, differences that don’t affect clinical decision-making.
Folate, also known as vitamin B9, is a crucial nutrient your body needs to make new cells and repair DNA. Doctors measure folate levels in your blood to check if you’re getting enough of this important vitamin. This research compared three different laboratory methods that doctors use to measure folate in blood samples. Scientists tested 58 blood samples using three different technologies and found that all three methods work well and give reliable results, though they sometimes show slightly different numbers. Understanding how these tests compare helps doctors choose the best method for checking your folate status.
Key Statistics
A 2026 research article analyzing 58 blood samples found that three laboratory methods for measuring folate (microbiological method, LC-MS/MS, and Tosoh immunoassay) all showed within-run imprecision of 7% or less, indicating excellent consistency and reliability.
According to research reviewed by Gram, the Tosoh CL1200 immunoassay showed a constant positive bias of 3-4 nmol/L compared to microbiological and LC-MS/MS methods when measuring 58 serum samples, though this small difference does not affect clinical accuracy.
A 2026 comparison of folate measurement methods found that both the microbiological method and LC-MS/MS showed accurate results when validated against NIST Standard Reference Material and VITAL External Quality Assessment targets.
The Quick Take
- What they studied: Whether three different laboratory methods for measuring folate in blood give similar and accurate results
- Who participated: 58 blood serum samples collected from people in the UK National Diet and Nutrition Survey
- Key finding: All three testing methods (microbiological method, LC-MS/MS, and Tosoh immunoassay) produced accurate and reliable results with very small differences between them
- What it means for you: If your doctor tests your folate level, the results should be trustworthy regardless of which testing method your lab uses, though results may vary slightly depending on the technology
The Research Details
Researchers took 58 blood samples and tested each one using three different laboratory methods to measure folate concentration. The three methods were: a microbiological method (which uses living organisms to detect folate), LC-MS/MS (a sophisticated chemical analysis technique), and a commercial immunoassay called Tosoh CL1200 (which uses antibodies to detect folate). They tested each sample multiple times to check how consistent each method was, and they compared the results against known standard samples to check accuracy.
The researchers also tested how well each method performed when measuring samples at different folate concentrations, some samples had low folate levels and others had higher levels. This helped them understand if one method might be better at detecting folate at certain levels.
Different laboratories around the world use different methods to measure folate, and doctors need to know if these methods give comparable results. If one method consistently gives higher or lower numbers than another, doctors might misdiagnose folate deficiency or miss it entirely. This study helps ensure that no matter which lab tests your blood, you’ll get reliable information about your folate status.
This study has several strengths: all three methods showed very good precision (consistency), with variation of 7% or less when the same sample was tested multiple times. Two of the methods were validated against official reference standards from NIST (the National Institute of Standards and Technology). The study used real blood samples from a national nutrition survey, making the results applicable to actual clinical practice. The main limitation is the relatively small sample size of 58 samples, which means the findings should be confirmed with larger studies.
What the Results Show
All three laboratory methods showed excellent consistency when testing the same sample multiple times, the variation was 7% or less, which is considered very good in laboratory testing. When compared to official reference standards, both the microbiological method and the LC-MS/MS method showed accurate results. The Tosoh immunoassay also showed good accuracy when compared to external quality assessment targets.
When the researchers compared the three methods directly using the 58 blood samples, they found that the LC-MS/MS and Tosoh methods gave results that were slightly higher than the microbiological method. The Tosoh method also showed an additional consistent difference of 3-4 nmol/L (a unit of measurement) compared to the other two methods. Despite these small differences, the researchers concluded that all three methods have acceptable accuracy and agreement for clinical use.
The study revealed that the Tosoh immunoassay had difficulty analyzing one type of sample (a plasma-based standard reference material), suggesting this method may not be suitable for all sample types. However, when tested with the types of samples typically used in clinical practice (serum samples), the Tosoh method performed well. The small differences between methods appear to be related to how each technology detects different forms of folate in the blood, which is an expected characteristic of these different testing approaches.
This research adds to existing knowledge about folate measurement methods by directly comparing three commonly used laboratory techniques in the same study. Previous research has validated individual methods, but this side-by-side comparison helps laboratories understand how results might differ if they switch from one method to another. The findings support that modern laboratory methods for folate measurement are sufficiently comparable for clinical decision-making.
The study used only 58 blood samples, which is a relatively small number for this type of comparison. A larger sample size would provide more confidence in the findings. The samples came from one UK nutrition survey, so the results may not apply to all populations worldwide. The study focused on comparing the methods themselves rather than looking at how folate deficiency affects health outcomes. Additionally, the study didn’t examine how factors like age, diet, or medical conditions might affect the comparability of these methods.
The Bottom Line
If your doctor orders a folate blood test, you can be confident the results are reliable regardless of which of these three methods your laboratory uses. The small differences between methods are not clinically significant for most purposes. If you’re being monitored for folate deficiency over time, try to have your tests done at the same laboratory using the same method for consistency, as this will make it easier to track changes in your folate levels.
This research matters most to laboratory professionals, doctors, and researchers who measure folate levels. It’s relevant for anyone being tested for folate deficiency, pregnant women (who need adequate folate to prevent birth defects), people with certain medical conditions affecting nutrient absorption, and those taking medications that interfere with folate. The findings are less critical for people with adequate folate intake and no risk factors for deficiency.
If you’re being tested for folate deficiency, you’ll get results within days to a week, depending on your laboratory. If you’re being treated for low folate, it typically takes 2-4 weeks of supplementation to see improvements in blood folate levels, though symptoms may improve at different rates.
Frequently Asked Questions
What is folate and why do doctors test for it?
Folate (vitamin B9) is essential for making new cells and repairing DNA. Doctors test folate levels to detect deficiency, which can cause anemia and birth defects. Low folate is common in certain medical conditions and with some medications.
Do different lab tests for folate give the same results?
A 2026 study of 58 blood samples found three common folate testing methods produce very similar results with only small differences (3-4 nmol/L). All three methods are accurate and reliable for clinical use, so your results should be trustworthy regardless of which method your lab uses.
How accurate are blood folate tests?
Research shows all three major folate testing methods have excellent accuracy when compared to reference standards. Each method shows consistency of 7% or less when testing the same sample multiple times, meeting high laboratory standards for reliability.
Should I worry if my folate test results differ between labs?
Small differences between labs are normal and expected due to different testing methods. A 2026 study found variations of 3-4 nmol/L between methods, which is clinically insignificant. For monitoring folate over time, use the same lab when possible for consistency.
Which folate test method is best?
A 2026 comparison found all three methods (microbiological, LC-MS/MS, and Tosoh immunoassay) are equally reliable for clinical purposes. The choice depends on laboratory equipment and efficiency rather than accuracy. Your doctor’s lab will use whichever method they have available.
Want to Apply This Research?
- Log your folate test results (in nmol/L or ng/mL) along with the date and laboratory name. Track this quarterly or as recommended by your doctor to monitor trends over time.
- Set reminders to consistently consume folate-rich foods like leafy greens, legumes, and fortified grains. If supplementing, log your daily folate supplement intake to correlate with test results.
- Create a chart showing your folate levels over time. Note any changes in symptoms (fatigue, weakness) alongside test results. If switching laboratories, record which method was used so you can account for expected small variations in results.
This article summarizes laboratory research comparing folate testing methods and is not medical advice. Folate test results should be interpreted by your healthcare provider in the context of your symptoms, medical history, and other test results. If you have concerns about your folate levels or are experiencing symptoms of deficiency (fatigue, weakness, shortness of breath), consult your doctor for proper evaluation and treatment. This research does not replace professional medical diagnosis or treatment recommendations.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.
