A low ferritin confirms deficiency; a normal one rules nothing out
Against bone marrow iron, a ferritin under 30 micrograms per litre caught 79% of the people who were deficient and wrongly flagged 2% of those who were not.
What the study found
A low ferritin settles it; a normal one settles nothing
Against bone marrow iron, a ferritin under 30 micrograms per litre caught 79% of the people who were deficient and wrongly flagged 2% of those who were not. It rules deficiency in confidently, and out poorly. On screening people without symptoms, the review found essentially no evidence.
The caveat · Studies set cut-offs from 12 to 200
The 30 microgram figure rests on 9 studies and 512 people, all graded low or very low certainty. The studies underneath it proposed thresholds anywhere from 12 to 200 micrograms per litre. And ferritin was far worse at spotting iron overload than deficiency.