A diagnosis of<unk>  requires further investigation into its cause. It can be caused by increased<unk>  demand, increased<unk>  loss, or decreased<unk>  intake. Increased<unk>  demand often occurs during periods of growth, such as in children and pregnant women. For example, during stages of rapid growth, babies and adolescents may outpace their dietary intake of<unk>  which can result in<unk>  in the absence of disease or a grossly abnormal diet.<unk>  loss is typically from blood loss. One example of blood loss is by chronic gastrointestinal blood loss, which could be linked to a possible cancer. In women of childbearing age, heavy menstrual periods can be a source of blood loss causing<unk> . People who do not consume much<unk>  in their diet, such as vegans or vegetarians, are also at increased risk of developing<unk> . Parasitic disease The leading cause of<unk>  worldwide is a parasitic disease known as a helminthiasis caused by infestation with parasitic worms (helminths); specifically, hookworms. The hookworms most commonly responsible for causing<unk>  include Ancylostoma duodenale, Ancylostoma ceylanicum, and Necator americanus. The World Health Organization estimates that approximately two billion people are infected with soil-transmitted helminths worldwide. Parasitic worms cause both inflammation and chronic blood loss by binding to a human's small-intestinal mucosa, and through their means of feeding and degradation, they can ultimately cause<unk> . Blood loss Red blood cells contain<unk> , so blood loss also leads to a loss of<unk> . There are several causes of blood loss including menstrual bleeding, gastrointestinal bleeding, stomach ulcers, and bleeding disorders. The bleeding may occur quickly or slowly. Slow, chronic blood loss within the body — such as from a peptic ulcer, angiodysplasia, inflammatory bowel disease, a colon polyp or gastrointestinal cancer (e.g., colon cancer)— can cause<unk> . Menstrual bleeding Menstrual bleeding is a common cause of<unk>  in women of child-bearing age. Women with menorrhagia (heavy menstrual periods) are at risk of<unk>  because they are at higher-than-normal risk of losing a larger amount blood during menstruation than is replaced in their diet. Most women lose about 40 mL of blood per cycle.<unk>  is lost with the blood. Some birth control methods, such as pills and IUDs, may decrease the amount of blood, therefore<unk>  lost during a menstrual cycle. Intermittent<unk>  supplementation may be as effective a treatment in these cases as daily supplements and reduce some of the adverse effects of long term daily supplements. Gastrointestinal bleeding The most common cause of<unk>  in men and post-menopausal women is gastrointestinal bleeding. There are many sources of gastrointestinal tract bleeding including the stomach, esophagus, small intestine, and the large intestine (colon). Gastrointestinal bleeding can result from regular use of some groups of medication, such as non-steroidal anti-inflammatory drugs (e.g. aspirin), as well as antiplatelets such as clopidogrel and anticoagulants such as warfarin; however, these are required in some patients, especially those with states causing a tendency to form blood clots. Colon cancer is another potential cause gastrointestinal bleeding, thus<unk> . Typically colon cancer occurs in older individuals In addition, some bleeding disorders can cause gastrointestinal bleeding. Two examples of bleeding disorders are von Willebrand disease and polycythemia vera. Diet In many countries, wheat flour is fortified with<unk> . The body normally gets the<unk>  it requires from foods. If a person consumes too little<unk> , or<unk>  that is poorly absorbed (non-heme<unk> , they can become<unk>  deficient over time. Examples of<unk> -rich foods include meat, eggs, leafy green vegetables and<unk> -fortified foods. For proper growth and development, infants and children need<unk>  from their diet. For children, a high intake of cow's milk is associated with an increased risk of<unk> . Other risk factors for<unk>  include low meat intake and low intake of<unk> -fortified products. The National Academy of Medicine updated Estimated Average Requirements and Recommended Dietary Allowances in 2001. The current EAR for<unk>  for women ages 14–18 is 7.9 mg/day, 8.1 for ages 19–50 and 5.0 thereafter (post menopause). For men the EAR is 6.0 mg/day for ages 19 and up. The Recommended Dietary Allowance is 15.0 mg/day for women ages 15–18, 18.0 for 19–50 and 8.0 thereafter. For men, 8.0 mg/day for ages 19 and up. (Recommended Dietary Allowances are higher than Estimated Average Requirements so as to identify amounts that will cover people with higher than average requirements.) The Recommended Dietary Allowance for pregnancy is 27 mg/day, and for lactation, 9 mg/day. For children ages 1–3 years it is 7 mg/day, 10 for ages 4–8 and 8 for ages 9–13. The European Food Safety Authority refers to the collective set of information as Dietary Reference Values, with Population Reference Intakes instead of Recommended Dietary Allowances, and Average Requirements instead of Estimated Average Requirements. For women the Population Reference Intake is 13 mg/day ages 15–17 years, 16 mg/day for women ages 18 and up who are premenopausal and 11 mg/day postmenopausal. For pregnancy and lactation, 16 mg/day. For men the Population Reference Intake is 11 mg/day ages 15 and older. For children ages 1 to 14 the Population Reference Intake increases from 7 to 11 mg/day. The Population Reference Intakes are higher than the US Recommended Dietary Allowances, with the exception of pregnancy.<unk>  malabsorption<unk>  from food is absorbed into the bloodstream in the small intestine, primarily in the duodenum.<unk>  malabsorption is a less common cause of<unk> , but many gastrointestinal disorders can reduce the body's ability to absorb<unk> . There are different mechanisms that may be present. In celiac disease, abnormal changes in the structure of the duodenum can decrease<unk>  absorption. Abnormalities or surgical removal of the stomach can also lead to malabsorption by altering the acidic environment needed for<unk>  to be converted into its absorbable form. If there is insufficient production of hydrochloric acid in the stomach, hypochlorhydria/achlorhydria can occur (often due to chronic H. pylori infections or long-term proton-pump inhibitor therapy), inhibiting the conversion of ferric<unk>  to the absorbable ferrous<unk> . Bariatric surgery is associated with an increased risk of<unk>  due to malabsorption of<unk> . During a Roux-en-Y anastamosis, which is commonly performed for weight management and diabetes control, the stomach is made into a small pouch and this is connected directly to the small intestines further downstream (bypassing the duodenum as a site of digestion). About 17-45% of people develop<unk><unk>  after a Roux-en-Y gastric bypass. Pregnant women Without<unk>  supplementation,<unk>  occurs in many pregnant women because their<unk>  stores need to serve their own increased blood volume, as well as be a source of hemoglobin for the growing baby and for placental development. Other less common causes are intravascular hemolysis and hemoglobinuria.<unk><unk>  in pregnancy appears to cause long-term and irreversible cognitive problems in the baby.<unk><unk>  affects maternal well-being by increasing risks for infections and complications during pregnancy. Some of these complications include pre-eclampsia, bleeding problems, and perinatal infections. Pregnancies where<unk><unk>  is present can lead to improper development of fetal tissues. Oral<unk>  supplementation during the early stages of pregnancy, specifically the first trimester, is suggested to decrease the adverse effects of<unk>  throughout pregnancy and to decrease the negative impact that<unk><unk>  has on fetal growth.<unk>  supplements may lead to a risk for gestational diabetes, pregnant women with adequate hemoglobin levels are recommended not to take<unk>  supplements.<unk><unk>  can lead to premature labor and to problems with neural functioning, including delays in language and motor development in the infant. Some studies show that women pregnant during their teenage years can be at greater risk of<unk>  due to an already increased need for<unk>  and other nutrients during adolescent growth spurts. Children Babies are at increased risk of developing<unk>  due to their rapid growth. Their need for<unk>  is greater than they are getting in their diet. Babies are born with<unk>  stores; however, these<unk>  stores typically run out by 4–6 months of age. In addition, infants who are given cow's milk too early can develop anemia due to gastrointestinal blood loss. Children who are at risk for<unk>  include: * Preterm infants * Low birth weight infants * Infants fed with cow's milk under 12 months of age * Breastfed infants who have not received<unk>  supplementation after age 6 months, or those receiving non-iron-fortified formulas * Children between the ages of 1 to 5 years old who receive more than 24 ounces (700 mL) of cow milk per day * Children with low socioeconomic status * Children with special health care needs * Children of Hispanic ethnicity * Children who are overweight Blood donation Frequent blood donors are also at risk for developing<unk> . When whole blood is donated, approximately 200 mg of<unk>  is also lost from the body. The blood bank screens people for anemia before drawing
Iron-deficiency anemia
Lead poisoning
Iatrogenic anemia
Megaloblastic anemia
Hemoglobinemia
Nutritional anemia
Sideroblastic anemia
Myelophthisic anemia