Iron Ferritin

Iron in Serum
Ferritin in Serum

Clinical Information

Iron (Fe) is an essential trace mineral. Unlike other nutrients, iron requirement cannot be solely met by the diet1 because of its low bioavailability. Iron from the diet have two forms, the heme and non-heme iron2.

Iron is needed for oxygen transport, muscle activity, mitochondrial function, and DNA synthesis3. It is an essential component of hemoglobin and myoglobin – oxygen carriers and transporters in the body. Furthermore, iron facilitates the transfer of electrons in the respiratory chain; hence, plays a role in ATP synthesis4.

Signs and Symptoms of Deficiency or Toxicity

Iron deficiency is prevalent both in developed and developing countries. Iron depletion occurs in several stages. During the early stage, iron stores are depleted but functional iron supply is not compromised. As the deficiency progresses, functional iron stores also begin to be depleted. Finally, iron-deficiency anemia (IDA) ensues when iron is no longer able to support normal red blood cell formation due to the lack of iron5. Iron deficiency results from poor diet, malabsorptive disorders, and blood loss disorders2.

Symptoms of iron deficiency are usually associated with anemia5. These includes fatigue, rapid hart rate palpitations, and rapid breathing on exertion5.

Iron overload from the diet does not normally happen due to its low bioavailability. However, short-term intake of 20 mg/kg iron from supplements or medications could lead to gastric upset, constipation, nausea, abdominal pain, vomiting, and faintness. In addition, an intake of 25 mg elemental iron can reduce zinc absorption2.

Supplementation Guide

Below are the recommendations of the World Health Organization regarding daily iron supplementation as a public health intervention8, 9.

(a) In settings where the prevalence of anemia in infants and young children is 40% or higher;
Infants and young children (6-23 months): 10-12.5mg elemental iron thru drops/syrups on a daily basis, three consecutive months in a year

(b) In settings where the prevalence of anemia in infants and young children is 40% or higher;
Preschool-age children (24-59 months): 30 mg elemental iron thru drops/syrups/tablets on a daily basis, three consecutive months in a year

(c) Where the prevalence of anemia in infants and young children is 40% or higher;
School-age children (5-12 y.o.): 3-60 mg elemental iron thru tablets or capsules daily, three consecutive months in a year.

(d) Where the prevalence of anemia in menstruating adult women and adolescent girls is 40% or higher;
Menstruating adult women and adolescent girls (non-pregnant females in the reproductive age group): 30-60 mg elemental iron thru tablets, daily, 3 consecutive months in a year.

Following are WHO recommendations for pregnant women1

(e) Where the prevalence of anemia in menstruating adult women and adolescent girls is 40% or higher;
Menstruating adult women and adolescent girls (non-pregnant females in the reproductive age group): 30-60 mg elemental iron thru tablets, daily, 3 consecutive months in a year.

(f) When the prevalence of anemia in pregnancy is < 40%: 60 mg iron + 400 mcg folic acid daily for 6 months in pregnancy

(g) When the prevalence of anemia in pregnancy is 40% or more: 60 mg iron + 400 mcg folic acid daily for 6 months during pregnancy, and continuing to 3 months postpartum

Below are the upper limits for iron intake1.

  • For infants, 0-11 months:50 mg
  • For children
    • 1-13 y.o.: 40 mg
    • 14-18 y.o.: 45 mg
  • For adults, 19 years and older: 45 mg
  • For pregnant/lactating: 45 mg

Iron can be affected by medications such as antacids10. Levedopa and levothyoxine reduce the absorption of the drug while proton inhibitors reduce iron absorption2.

Food Sources

Iron can be found in foods of both animal and plant origin. However, the more absorbable form (heme iron), is rich in red meats. Non-heme iron is found in green leafy vegetables. To improve the absorption of iron from non-heme sources, food must be taken with vitamin C rich foods. Following are sources dietary sources of iron: beef, fortified cereals, beans, oysters, molasses, lentils, firm tofu, kidney beans, cashews, spinach, potatoes (with skin), shrimp, light tuna, eggs, tomatoes, raisins, and prunes12.

(1) Philippine Dietary Reference Intakes. 2015. Department of Science Technology-Food and Nutrition Research Institute.
(2) Office of Dietary Supplements-National Institutes of Health. (n.d.). Iron. Fact Sheet for Health Professional. Retrieved from https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
(3) Drakesmith H. Next-generation biomarkers for iron status. Nestle Nutrition Institute Workshop Series 2016; 84: 59-69. doi: 10.1159/000436955.
(4) Huskisson E, Maggini S, Ruf M. The role of vitamins and mineral in energy metabolism and well-being. The Journal of International Medical Research 2007; 35: 277-289
(5) Higdon J, Drake VJ, Delage B. (April 2016). Linus Pauling Institute. Micronutrient Information Sheet. Iron. Retrieved from http://lpi.oregonstate.edu/mic/minerals/iron
(6) de Souza S, Shet A, Kapavarapo PK, Shet AS. Evaluating biomarkers of iron deficiency in anemia of inflammation. Blood 2013; 122 (21):948. Retrieved from http://www.bloodjournal.org/content/122/21/948.
(7) Wang W, Knovich MA, Coffman LG, Torti FM, Torti SV. Serum Ferritin: Past, Present and Future. Biochimica et biophysica acta. 2010;1800(8):760-769. doi:10.1016/j.bbagen.2010.03.011.
(8) Daily iron supplementation in infants and children. Geneva: World Health Organization; 2016.
(9) Guideline: Daily iron supplementation in adult women and adolescent girls. Geneva: World Health Organization; 2016.
(1) International Nutritional Anemia Consulttative Group (INACG), World Health Organization (WHO), United Nations Childrens Fund (UNICEF). (1998). Guidelines for Iron Supplementation to Prevent Iron Deficiciency Anemia. In R.J. Stoltzfus and M.L. Dreyfuss (Eds.). Guidelines for the use of iron supplements to prevent and treat iron deficiency anemia. Washington DC: ILSI Press.
(11) Diab L, Krebs NF. Vitamin Excess and Deficiency. Pediatrics in Review 2018; 39(4): 161-179.
(12) Linus Pauling Institute. Oregon State University. (n.d.). Micronutrients for Health. Retrieved from http://lpi.oregonstate.edu/sites/lpi.oregonstate.edu/files/pdf/mic/micronutrients_for_health.pdf