Iron Deficiency Difficult to Prove if B12 Deficiency is Also Present

Don’t Conclude Your Patient Has Normal Iron Status Until You are 100 % Confident His or Her B12 Levels are Normal

A study from 2015 reminds us that we can’t get overly confident that the patient in front of us has a truly normal iron status until we can prove the ferritin levels are normal AND the vitamin B12 levels are normal too!

The 2015 Solmaz Study

Solmaz and colleagues studied 75 patients with vitamin B12 deficiency. Complete blood counts and serum levels of iron, unsaturated iron binding capacity (UIBC), ferritin, vitamin B12, and thyroid stimulant hormone were determined at the time of diagnosis and then again after completing treating with vitamin B12 therapy.

Before vitamin B12 therapy, the authors found increased serum iron levels (126.4 ± 63.4 µg/dL), decreased serum UIBC levels (143.7 ± 70.8 µg/dL), increased serum ferritin levels (192.5 ± 116.4 ng/mL), and increased transferrin saturation values (47.2 ± 23.5 %). After treatment with vitamin B12 therapy, serum iron levels (59.1 ± 30 µg/dL), serum ferritin levels (44.9 ± 38.9 ng/mL) and transferrin saturation values (17.5 ± 9.6 %) decreased, and serum UIBC levels (295.9 ± 80.6 µg/dL) increased. These differences were all statistically significant (p < 0.0001).

Seven patients (9.3 %) were felt to have true iron deficiency before vitamin B12 therapy was started but yet 37 (49.3 %) had iron deficiency after cobalamin therapy.

Conclusion

I really like this study!

The data in this study suggest that iron deficiency is common in patients with vitamin B12 deficiency, and that B12 deficiency can mask an underlying iron deficiency. All patients with vitamin B12 deficiency  should be screened for iron deficiency, particularly after vitamin B12 treatment is done and levels of B12 come up to a normal level. In addition, all patients with even the most remote concerns for iron deficiency (low hemoglobin, etc) should be sceened for B12 deficiency as well. We can’t really be confident that a patient doesn’t truly have iron deficiency until B12 levels are proven to be normal or brought up to normal.

Reference

Solmaz et al. Cobalamin Deficiency Can Mask Depleted Body Iron Reserves. Indian J Hematol Blood Transfus. 2015 Jun; 31(2): 255–258.

Carmel et al. Iron deficiency occurs frequently in patients with pernicious anemia. JAMA. 1987 Feb 27;257(8):1081-3.