Serum Creatinine Reference Interval and Discordance with Manufacturer-Supplied Limits in Apparently Healthy Mauritanian Adult Male Blood Donors: A Cross-Sectional Study
This cross-sectional study of 272 apparently healthy Mauritanian adult male blood donors reveals that the locally derived serum creatinine reference interval (6.50–15.10 mg/L) is significantly wider than manufacturer-supplied limits, resulting in over 22% of men being misclassified as having abnormal kidney function and highlighting the critical need for local verification of reference ranges.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
To understand how the human body filters waste, doctors often look at a substance called creatinine. This chemical is a natural byproduct of muscle activity, constantly produced and then cleaned out of the blood by the kidneys. Because the kidneys are the primary workers removing it, the amount of creatinine left in the blood serves as a reliable gauge of how well those organs are functioning. If the levels are too high, it can signal that the kidneys are struggling. However, what counts as a "normal" amount is not the same for everyone. It depends on a person's muscle mass, age, and sex, as well as the specific machine used to measure the chemical in a laboratory. For years, many clinics have relied on standard ranges provided by the manufacturers of these testing machines, assuming these limits apply to everyone everywhere. But in a country like Mauritania, where local data has been scarce, doctors have had to guess whether those standard numbers truly fit the people walking through their doors.
A team of researchers in Nouakchott set out to find the answer by looking at the blood of healthy adult men who had just donated blood. They focused on a group of 272 men who were deemed healthy enough to give blood, meaning they did not have known chronic diseases or obesity. Using a specific type of testing machine common in the region, they measured the creatinine levels in their blood samples. The goal was simple: to see if the standard limits used by the machine's manufacturer matched the reality of these Mauritanian men. The researchers found that the standard limits did not tell the whole story. While the manufacturer suggested that a normal range for men fell between 7.0 and 12.0 milligrams per liter, the actual measurements from the local donors told a different tale.
The study revealed that the healthy Mauritanian men had a much wider range of normal creatinine levels than the machine suggested. The researchers calculated that for this specific group, a normal range extends from 6.50 to 15.10 milligrams per liter. This difference is significant because it means that nearly one in five of the healthy men in the study would have been flagged as having abnormal kidney function if doctors had strictly followed the manufacturer's upper limit. Specifically, 52 men had levels higher than the standard cutoff, yet they were healthy blood donors with no known kidney issues. The study also looked at whether factors like age or body weight explained these differences. While heavier men were more likely to have levels that fell outside the manufacturer's narrow range, age did not seem to play a major role in this specific group of young adults.
The findings suggest that relying blindly on the numbers printed on a machine's manual can lead to confusion. In this case, using the standard limits would have incorrectly labeled many healthy men as having potential kidney problems. The researchers emphasize that their new range is specific to the type of testing method used and the population studied. It is not a universal rule for all kidney disease diagnosis, but rather a crucial correction for how healthy people in this region should be measured. Before this new range can be adopted widely, it needs to be confirmed by other studies involving more diverse groups, including women and older adults. For now, the work serves as a vital reminder that medical standards must be checked against the local reality to ensure that healthy people are not mistaken for the sick.
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