Practice Points

1. Iron sufficiency is usually measured with serum ferritin rather than iron saturation.
2. Over two years, 154,086 iron status tests were undertaken by family doctors in Eastern Health; 80% of
   these were in patients with normal hemoglobin.
3. Overtesting occurred in patients with normal hemoglobin and normal MCV/MCH: only 6% had low ferritin and 0.3%
   > 1000 μg/L.
4. Undertesting occurred in anemic patients with low MCV/MCH: less than a third of women under 40 who could benefit from oral iron had iron status testing, as did just over a third of adults over 60 who might need a work-up for Gastrointestinal cancer.
5. Asymptomatic non-anemic patients should not be tested for ferritin, and testing should be individualized in symptomatic non-anemic patients, as it is uncertain whether treatment of hypoferritinemia with oral iron will lead to clinical benefits.
6. Patients with anemia and low MCV should be tested for ferritin, because: (a) Older adults with iron deficiency anemia should be investigated for gastro-intestinal cancer. (b) Women of reproductive age require iron if iron deficient.

Data from Eastern Health on the use of iron testing (serum ferritin and iron saturation) and CBC were analyzed for 2014 to 2016.

• 80% of iron tests were undertaken in non-anemic patients.
• 97% of non-anemic patients had normal MCV/MCH.

• 46% of non-anemic patients had an iron test.

Potential Unnecessary Testing

The number of ferritin tests done in people with normal HGB, MCV, and MCH in the two years.

We do not have data on the indication for the tests. It is possible that some were symptomatic with fatigue or other symptoms. We also do not know if any were treated with iron or whether they showed a clinical response. The literature suggests a limited benefit to iron therapy in those without anemia or a low MCV.

• Iron testing should be selective in the presence of normal HGB and normal MCV/MCH.
• Ferritin tests are not indicated in asymptomatic patients with normal hemoglobin level and normal MCV, unless hemochromatosis is suspected/diagnosed.

Number of ferritin tests done in people with normal HGB, MCV, and MCH (2014-16)

Iron Testing in Anemic Patients by MCV/MCH Level

Number of iron tests ordered by family doctors, by anemia (2014-16)

Missed Opportunity for Testing

This figure shows the number of adults aged > 60 with anemia and a low MCV who DID NOT have an iron test within three months of a Family Doctor-ordered CBC.

This figure shows the number of women aged < 40 with anemia and a low MCV who DID NOT have an iron test within three months of a Family Doctor-ordered CBC. It is unknown whether these women were treated with iron supplements.

The analysis reveals both potential over- and under-use of iron testing.

OVER testing in those without anemia is substantial, low yield and costly. A ferritin test costs $10.

Although small in number, UNDER testing adults over the age of 60 with likely iron deficiency anemia risks not diagnosing bowel cancer. UNDER testing women aged less than 40 with likely iron deficiency anemia may be associated with a missed opportunity to treat symptoms and to prevent problems in pregnancy.

This report relates to testing in out-patients.