10/03/2026
We've always been a little nerdy when it comes to lab references ranges and here is a great example why. For a long time, many people were told their ferritin was “normal” because it fell within the reference range. The evidence is asking us to look at that differently.
And the Ontario data are hard to ignore. In a study of more than 784,000 females aged 15 to 54 who had outpatient testing, 38.3% had iron deficiency without anemia. More than half of those with iron deficiency anemia had a normal MCV.
But this is about more than changing a number on a lab report.
Those living in the lowest income neighbourhoods had the highest odds of anemia and were also the least likely to have their ferritin tested. Better thresholds matter, but so does asking who is being tested, who is being missed and why.
New Canadian and international guidance continues to move this conversation forward, including recognizing that different clinical situations may require different thresholds and ways of interpreting ferritin.
For us, that is the important part. Use the best evidence we have, keep asking better questions, and consider the whole context around the person in front of us.
If you want to dig a little deeper, the CMAJ Podcast episode “Fixing the Flag: A New Standard for Diagnosing Iron Deficiency” is a great listen, along with the Raise the Bar initiative and the work of Wen, Sholzberg and colleagues.
For Educational information only.
