A study in Israel found that increasing iron intake among infants with anemia increased serum 25(OH)D levels, likely through improving intestinal absorption:

In 13 of 17 infants (aged 10.5 +/- 4.3; mean +/- SD mo) with iron-deficiency anemia, the serum 24,25-dihydroxyvitamin D concentration was below the normal range and in 9 of these 13 the serum 25-hydroxyvitamin D concentration was below the normal range despite the fact that these infants received 10 micrograms vitamin D/d from the age of 1 mo. The infants were treated with intramuscular iron dextran (Imferon). The iron-dextran treatment increased the hemoglobin and serum iron concentrations as well as 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D concentrations. It is known that iron deficiency impairs fat and vitamin A intestinal absorption. Therefore, it is suggested that absorption of vitamin D may also be impaired. This may contribute to the development of vitamin D deficiency. Iron supplementation may have improved the absorption of vitamin D in the small intestine and hence increased the vitamin D concentration in the plasma1.

Anemia can be treated with erythropoiesis-stimulating agents (ESAs) or erythropoietin (EPO)2. In a study of patients with chronic kidney disease (CKD) in Hungary, both hemoglobin and the ESA dose/hemoglobin index were directly correlated with serum 25(OH)D levels3.

Another study reported a 30% reduction in efficiency of Epoetin alfa in hemoglobin sensitivity as PTH levels increased from 0 to 1000 pg/ml4. Thus, serum 25(OH)D levels should be measured and increased to adequate levels for those with CKD. 1,25(OH)2D can also be used2, but only under close supervision by a medical doctor.

A study in Los Angeles found that increasing serum 25(OH)D levels reduced the requirement for erythropoiesis stimulating agent for chronic kidney disease patients with anemia:

BACKGROUND: Investigate whether changes in vitamin D levels affected erythropoiesis stimulating agent (ESA) requirements in chronic kidney disease (CKD) patients with anemia.
METHODS: A retrospective cohort study of nondialysis-dependent patients with CKD of all stages. Patients were anemic and on ESA with at least 2 documented 25-hydroxylated vitamin D (D25) levels drawn 4 months apart. Patients were grouped based on the change in their D25 levels. The primary end point evaluated was absolute change in the ESA doses needed to maintain target hemoglobin levels between 11 and 12 g/dl.
RESULTS: A total of 153 patients met the inclusion criteria for analysis. With the exception of the normal-to-low D25 group, patients showed a trend toward lower ESA doses with time. The low-to-normal vitamin D group showed a significant reduction in dose of 24% (1,415 units, p = 0.025). The normal-to-low group, however, showed a 22% increase in dose of 1,270 units (NS). Levels of Ca, PTH, and iron indexes were similar across all groups.
CONCLUSION: Our retrospective cohort study demonstrates an ESA sparing effect in patients with vitamin D deficiency after repletion to normal levels. Conversely, there was a trend toward increased ESA requirements in patients who became vitamin D deficient from a previously normal state5.

Since the liver plays a central role in vitamin D metabolism, those with liver disease are at increased risk of low serum 25(OH)D levels. A study in Australia found that those with liver disease and serum 25(OH)D levels less than 10 ng/ml had an increased risk of anemia6. Those with liver disease should also be tested for 25(OH)D deficiency.

Page last edited: 08 May 2011


  1. Heldenberg, D. Tenenbaum, G. Weisman, Y. Effect of iron on serum 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D concentrations. Am J Clin Nutr. 1992 Sep; 56 (3): 533-6.
  2. Brancaccio, D. Cozzolino, M. Gallieni, M. Hyperparathyroidism and anemia in uremic subjects: a combined therapeutic approach. J Am Soc Nephrol. 2004 Jan; 15 Suppl 1S21-4.
  3. Kiss, Z. Ambrus, C. Almasi, C. Berta, K. Deak, G. Horonyi, P. Kiss, I. Lakatos, P. Marton, A. Molnar, M. Z. Nemeth, Z. Szabo, A. Mucsi, I. Serum 25(OH)-Cholecalciferol Concentration Is Associated with Hemoglobin Level and Erythropoietin Resistance in Patients on Maintenance Hemodialysis. Nephron Clin Pract. 2010 Nov 12; 117 (4): c373-c378.
  4. Gaweda, A. E. Goldsmith, L. J. Brier, M. E. Aronoff, G. R. Iron, inflammation, dialysis adequacy, nutritional status, and hyperparathyroidism modify erythropoietic response. Clin J Am Soc Nephrol. 2010 Apr; 5 (4): 576-81.
  5. Lac, P. T. Choi, K. Liu, I. A. Meguerditchian, S. Rasgon, S. A. Sim, J. J. The effects of changing vitamin D levels on anemia in chronic kidney disease patients: a retrospective cohort review. Clin Nephrol. 2010 Jul; 74 (1): 25-32.
  6. McGillivray, G. Skull, S. A. Davie, G. Kofoed, S. E. Frydenberg, A. Rice, J. Cooke, R. Carapetis, J. R. High prevalence of asymptomatic vitamin D and iron deficiency in East African immigrant children and adolescents living in a temperate climate. Arch Dis Child. 2007 Dec; 92 (12): 1088-93.