Is it still worth checking iron levels with a normal hemoglobin result?

Iron Testing is Necessary Even with Normal Hemoglobin

Yes, it is worth checking iron levels even with a normal hemoglobin of 15.7 g/dL, as normal hemoglobin does not exclude iron deficiency. Hemoglobin is a late indicator of iron deficiency, and you can have depleted iron stores with a normal hemoglobin value 1.

Why Iron Testing is Important with Normal Hemoglobin

Iron deficiency occurs in stages:

1. Depleted iron stores (low ferritin, normal hemoglobin)
2. Iron-deficient erythropoiesis (abnormal iron studies, normal hemoglobin)
3. Iron deficiency anemia (low hemoglobin, microcytosis, hypochromia)

Hemoglobin concentration and hematocrit are considered "late indicators" of iron deficiency 1. This means you can have significant iron depletion while still maintaining a normal hemoglobin level.

Key points to consider:

• Biochemical tests like serum ferritin, transferrin saturation, and serum iron can detect earlier changes in iron status before hemoglobin drops 1.
• Serum ferritin is the single most useful marker of iron deficiency 1.
• The BSG guidelines recommend that iron deficiency should be confirmed by iron studies prior to further investigation 1.

Benefits of Detecting Iron Deficiency Before Anemia Develops

Early detection of iron deficiency (before anemia develops) offers several advantages:

• Prevention of progression to iron deficiency anemia
• Improved physical performance - Research shows that even iron depletion without anemia can negatively impact physical performance 2, 3
• Reduced fatigue and improved quality of life - Iron deficiency without anemia can cause symptoms similar to iron deficiency anemia 4

In a study of female collegiate rowers, those with iron depletion without anemia (serum ferritin <20 μg/L but normal hemoglobin) performed significantly worse in a 2-km race compared to those with normal iron status, with times approximately 21 seconds slower 2.

Recommended Iron Tests

If you decide to check iron status, the following tests are recommended:

• Serum ferritin - The most specific test for iron deficiency; levels <30 μg/L generally indicate low iron stores 1
• Transferrin saturation - Helpful if false-normal ferritin is suspected (e.g., in inflammatory conditions) 1
• Serum iron - Part of a complete iron panel

Common Pitfalls to Avoid

1. Relying solely on hemoglobin/hematocrit - These are late indicators of iron deficiency 1, 5
2. Misinterpreting normal red blood cell indices - MCV and MCH may be normal despite iron depletion 5
3. Not considering ferritin as an acute phase reactant - Inflammation can falsely elevate ferritin levels, masking iron deficiency 1

Conclusion

While your hemoglobin level of 15.7 g/dL is normal, this does not exclude iron deficiency. Checking iron studies, particularly serum ferritin, is worthwhile to detect potential iron depletion before it progresses to anemia, especially if you have risk factors for iron deficiency or symptoms that could be related to iron deficiency.