According to research reviewed by Gram, the CKD-EPI Pakistan formula gave the most accurate kidney filtration estimates in healthy Pakistani adults, overestimating by about 9 mL/min compared with the gold-standard DTPA test. Other common formulas overestimated by about 20 to 24 mL/min.
Kidney doctors use blood tests and math formulas to estimate how well the kidneys filter waste, but these formulas were mostly built using data from other populations. A 2026 study from Multan Institute of Kidney Diseases in Pakistan compared three common formulas against a gold-standard test called DTPA in 223 healthy adults. All three formulas gave estimates that ran higher than the DTPA test, but the CKD-EPI Pakistan formula came closest, overestimating by about 9 mL/min on average. The older MDRD formula overestimated by about 24 mL/min. According to research reviewed by Gram, the findings suggest that formulas calibrated for a specific population may give more reliable results, though larger studies are needed before guidelines change.
Key Statistics
A 2026 cross-sectional study of 223 healthy Pakistani adults found that the CKD-EPI Pakistan formula overestimated kidney filtration by about 9 mL/min compared with the gold-standard DTPA test.
The same 2026 study reported that the older MDRD formula overestimated kidney filtration by about 24 mL/min and had the widest range of error, with a mean absolute error of 29.27.
A 2026 study from Multan, Pakistan found that the correlation between all three creatinine-based kidney formulas and the DTPA test was weak.
The Quick Take
- What they studied: The researchers wanted to know which of three common kidney filtration formulas gives the most accurate estimate for healthy adults in Pakistan, when compared with a precise laboratory test.
- Who participated: The study looked at 223 healthy adults who were screened as possible kidney donors at a kidney hospital in Multan, Pakistan, between January 2021 and June 2025. Their records were reviewed after the fact.
- Key finding: The CKD-EPI Pakistan formula gave an average estimate of 109 mL/min, compared with 100 mL/min from the gold-standard DTPA test. That is an overestimate of about 9 mL/min. The other two formulas overestimated by about 20 to 24 mL/min. Even the best formula showed only a weak match to the lab test for individual people.
- What it means for you: This study does not change what you should do about your kidney health. It suggests that doctors in Pakistan may get more reliable results from a formula designed for the local population. If you have questions about your kidney test results, talk with your doctor.
The Research Details
This was a cross-sectional study, which means researchers took a snapshot of information at one point in time instead of following people over many years. The team reviewed records from healthy adults who had already undergone routine screening for kidney donation. Each person had a kidney filtration rate measured with DTPA, a radioactive tracer that is injected into the body and tracked as it leaves through the kidneys. DTPA is considered the gold standard because it measures filtration directly rather than estimating it.
For the same people, the researchers also calculated filtration estimates using three math formulas based on a simple blood test called creatinine, which is a waste product made by muscles. Creatinine levels, along with age, sex, and sometimes other factors, go into these formulas. The researchers then compared each formula’s estimate to the DTPA result. They measured how closely the numbers tracked together, how far apart the estimates and lab results typically were, and how large the average error was.
Because the study used records that already existed, the researchers did not assign people to different treatments or follow their health over time. This type of design is useful for checking how accurate a measurement tool is, but it cannot show whether using one formula leads to better health outcomes for patients.
Kidney filtration rate is one of the most important numbers doctors use to judge kidney health, and it often guides decisions about medicine doses and whether a person needs specialist care. If the formula used to estimate that number is off, a doctor might think a person’s kidneys are healthier or weaker than they really are. Comparing each formula directly to a gold-standard lab test is the most direct way to find out which one is more accurate.
The study also matters because most of the formulas used worldwide were developed using data from people in Europe, North America, or other regions. Testing them in a local group helps show whether those tools fit people with different body sizes, muscle mass, diets, or genetics. Finding that a locally calibrated formula performs better is a useful signal for health systems in similar settings.
The study used a well-established gold-standard test as its reference point, which is a strength. It used several standard statistical methods to measure accuracy, including Bland-Altman analysis, which is widely used for comparing two measurement methods. Results were reported with both the average difference and the range of likely differences, which gives a fuller picture.
There are also important limits to keep in mind. The study used past records rather than a planned research design, and it was conducted at a single hospital. The group included only healthy adults screened for kidney donation, so the results may not apply to people with existing kidney disease, older adults, or people from other parts of Pakistan or other countries. The abstract does not clearly state the total sample size in the summary fields, though 223 adults are reported in the text. The study was published in a peer-reviewed medical journal, but as a single cross-sectional study it should be viewed as one piece of evidence rather than a final answer.
What the Results Show
All three formulas tended to overestimate kidney filtration compared with the DTPA test. The average DTPA result was about 100 mL/min per 1.73 square meters of body surface, a common way of adjusting for body size. The CKD-EPI Pakistan formula averaged about 109 mL/min, the CKD-EPI 2021 formula averaged about 120 mL/min, and the MDRD formula averaged about 124 mL/min.
The size of the typical overestimate was the clearest difference between the formulas. The CKD-EPI Pakistan formula had the smallest average bias, at about 9 mL/min higher than the lab test. The MDRD formula had the largest bias, at about 24 mL/min. The range of likely differences for an individual person, called the limits of agreement, was also narrowest for the CKD-EPI Pakistan formula, running from about 22 mL/min below to about 40 mL/min above the lab result. For MDRD, that range was much wider, from about 37 mL/min below to about 84 mL/min above.
Accuracy at the level of individual people was measured using average error numbers. The CKD-EPI Pakistan formula had a mean absolute error of about 14 and a root mean square error of about 18. The MDRD formula had errors of about 29 and 39. Lower numbers mean closer matches. Although these error numbers favored the CKD-EPI Pakistan formula, the researchers also found that the correlation between every formula and the DTPA test was weak. This means that even the best formula does not reliably track the lab result from one person to the next.
The researchers concluded that the CKD-EPI Pakistan formula showed the best overall agreement with the gold-standard test among the three options. This result points to the value of calibrating kidney formulas to the population they will be used on. The wider error ranges of the older MDRD formula also suggest that it may be less dependable for estimating filtration in this group.
Because the study focused on healthy adults, the findings mainly speak to how well the formulas perform when kidney function is expected to be normal. The researchers did not report whether the formulas gave different results for men and women, older and younger people, or people with different body types in a way that would change clinical decisions. These are areas that future work could explore.
Many earlier studies have found that creatinine-based formulas can be imprecise, especially when used outside the populations where they were developed. Several international studies have reported that newer formulas, including CKD-EPI 2021, perform better than older ones such as MDRD, while still showing room for error. This study fits that pattern by finding that MDRD overestimated the most.
The finding that a formula developed for Pakistani populations performed better than the more widely used international versions adds support to the idea that local calibration can improve accuracy. At the same time, the study authors note that international validation is needed before global guidelines are changed. Other groups have reported similar tendencies to overestimate in healthy people, so this result is consistent with a broader body of work rather than a single surprising discovery.
The study looked back at existing records, so the researchers could not control how the tests were done or ensure that every participant was measured under the same conditions. It was conducted at one hospital in one city, which limits how well the results represent the wider population of Pakistan. The group consisted of healthy adults who had been screened as possible kidney donors, so they may differ from people who are seeing a doctor for kidney concerns.
The correlation between the formulas and the gold-standard test was weak, and the range of likely differences for any one person was wide. This means the formulas are better at showing averages across a group than at giving a precise answer for a single person. The DTPA test is also not used routinely in most clinics because it is costly and requires specialized equipment, so the reference point itself is not widely available. Finally, the study measured accuracy but did not test whether using one formula leads to better patient outcomes, such as earlier detection of kidney disease or better medication decisions.
The Bottom Line
Research shows that the CKD-EPI Pakistan formula gave estimates closer to the gold-standard test than the other two formulas in this group of healthy Pakistani adults. Based on this single cross-sectional study, the evidence supports further testing of locally calibrated formulas, which is a moderate level of confidence. Evidence is not yet strong enough to change routine clinical guidelines, and the study authors themselves call for international validation. Anyone with concerns about their kidney function should follow the advice of a qualified doctor rather than relying on a formula alone.
Doctors, laboratory staff, and health policy teams in Pakistan and similar settings may find this study useful when deciding which filtration formula to use. Researchers studying kidney health in South Asian populations may also find it helpful. People who are healthy and simply curious about kidney health may find it interesting, but this study is not a reason to change medical care. People with known kidney disease, diabetes, high blood pressure, or who are on kidney-affecting medications should discuss their results with their own doctor, since this study did not include those groups.
This study is a single snapshot and does not show changes over time, so it does not offer a timeline for health benefits. Any change in how kidney formulas are used in clinics would likely take several years, as it requires additional studies in different populations, review by professional societies, and updates to clinical guidelines. For individuals, the more practical timeline is about how often to check kidney function, which your doctor will set based on your health history.
Frequently Asked Questions
Which kidney filtration formula is most accurate for Pakistani adults?
Research reviewed by Gram found that the CKD-EPI Pakistan formula gave the closest estimates among three tested options in 223 healthy adults. It overestimated filtration by about 9 mL/min compared with the gold-standard DTPA test, while the MDRD formula overestimated by about 24 mL/min.
What is DTPA and why is it considered the gold standard for kidney testing?
DTPA is a radioactive tracer injected into the body that is measured as it leaves through the kidneys. It is considered the gold standard because it measures kidney filtration directly rather than estimating it from blood levels, but it is costly and not routinely used in most clinics.
Can a kidney filtration formula tell me exactly how well my kidneys work?
No single formula can give an exact answer for one person. This study found weak correlation between creatinine-based formulas and the reference test, meaning estimates are more useful for averages across groups. Your doctor can interpret your results alongside your health history and other tests.
Should I change my kidney medicine or diet based on this study?
This study does not support changing medicine or diet on its own. It compared formulas in healthy adults and did not test patient outcomes. Anyone with kidney concerns should discuss results and any changes with a qualified doctor before making decisions.
Want to Apply This Research?
- If your doctor has ordered a creatinine blood test and reported an estimated filtration rate, log the date, the reported number, the formula name if your lab lists it, and your doctor’s comments. Recording the same test at the same lab over time gives you a consistent trend to discuss at appointments.
- Use the app to set a reminder before your next scheduled kidney blood test, and write down any questions about the formula or result to bring to your appointment. Encourage regular hydration, a balanced diet lower in excess salt, and regular physical activity, as these support overall kidney health, but do not change medicines or diet for kidney reasons without medical advice.
- Over the long term, track your estimated filtration results, blood pressure, and blood sugar readings in one place so patterns are easy to see. Review the trend with your doctor at each scheduled visit, and treat small single-test differences with caution, since formulas vary in accuracy and day-to-day lab results can fluctuate.
This article summarizes a single cross-sectional study of 223 healthy adults at one hospital in Pakistan and is for general information only. It is not medical advice and does not replace consultation with a qualified healthcare professional. Kidney filtration estimates should be interpreted by a doctor who knows your full health history, and you should not change any medicine, diet, or treatment based on this research without professional guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.