Anemia, defined by a reduced number of red blood cells or a low concentration of hemoglobin, affects a significant portion of the elderly population. The World Health Organization defines anemia as a hemoglobin level below 13 g/dL for men and below 12 g/dL for women. While prevalence increases with age, reaching up to 40% in hospitalized older patients, anemia is not a normal consequence of aging. Instead, it serves as a strong indicator of underlying health issues, often resulting from multiple contributing factors. A thorough investigation is necessary to identify the specific, treatable causes behind the low blood count.
Nutritional Deficiencies
Deficiencies in specific vitamins and minerals are common and easily managed causes of anemia in older adults. Iron deficiency anemia occurs when the body lacks sufficient iron to produce hemoglobin, which transports oxygen. This deficiency often stems from inadequate dietary intake or compromised absorption within the digestive tract.
Vitamin B12 and folate are required for healthy red blood cell formation, and a lack of either can lead to megaloblastic anemia. B12 deficiency is particularly prevalent in the elderly due to age-related changes like atrophic gastritis, which reduces stomach acid production. Lower acidity impairs B12 release from food proteins, preventing its binding to intrinsic factor necessary for absorption. Folate deficiency is less common than B12 deficiency because folate stores deplete faster and it is frequently included in fortified foods.
Anemia of Inflammation and Chronic Organ Dysfunction
The most frequent cause of anemia in the elderly is Anemia of Chronic Disease (ACD), also called Anemia of Inflammation, linked to underlying chronic illnesses. Conditions such as rheumatoid arthritis, heart failure, and cancer trigger persistent low-grade inflammation. Inflammatory signaling molecules, notably interleukin-6 (IL-6), stimulate the liver to produce high levels of the hormone hepcidin.
Hepcidin excess production sequesters iron in storage cells, such as macrophages, and prevents its absorption from the gut. This mechanism involves hepcidin binding to and promoting the destruction of ferroportin, the protein responsible for exporting iron into the bloodstream. Consequently, the iron needed for new red blood cell production becomes functionally unavailable, even if total iron stores are adequate. This functional iron deficiency impairs the bone marrow’s ability to respond to signals that stimulate red cell creation.
Anemia is also associated with Chronic Kidney Disease (CKD). Healthy kidneys produce erythropoietin (EPO), a hormone that stimulates red blood cell production in the bone marrow. As kidney function declines, EPO production is significantly reduced, leading to an insufficient signal for red blood cell synthesis. Furthermore, the chronic inflammation often present in CKD contributes to the iron sequestration mechanism seen in ACD, making the anemia multifactorial.
Primary Disorders of Blood Cell Production and Chronic Loss
Some anemia causes originate directly from bone marrow problems. Myelodysplastic Syndromes (MDS) are acquired disorders where the bone marrow fails to produce healthy, mature blood cells, including red blood cells. MDS is strongly age-related, often resulting in macrocytic anemia, where red blood cells are abnormally large. This disorder is a significant cause of unexplained anemia in older individuals and may be accompanied by low white blood cell or platelet counts.
Chronic blood loss from the gastrointestinal (GI) tract is a frequent source of absolute iron deficiency anemia in the elderly. This loss is often occult, meaning it is not visible and can persist unnoticed for long periods. Common causes include peptic ulcers, diverticulosis, angiodysplasia, and malignancies. The use of medications like nonsteroidal anti-inflammatory drugs (NSAIDs) and anticoagulants significantly increases the risk of GI bleeding.
Diagnostic Approaches and Medication Contributions
Specific laboratory testing is required to differentiate nutritional iron deficiency from the anemia of inflammation. Iron deficiency anemia is characterized by a low serum ferritin level, reflecting low total iron storage. Conversely, in Anemia of Chronic Disease, ferritin levels are often normal or elevated because ferritin rises in response to inflammation. Low transferrin saturation, which measures actively circulating iron, is a useful marker that is low in both conditions.
The concurrent use of multiple medications, known as polypharmacy, is an often-overlooked factor contributing to anemia. Certain drug classes can directly contribute through various mechanisms. For instance, chemotherapy and some antibiotics can suppress bone marrow function, inhibiting red blood cell production. NSAIDs and antiplatelet agents increase the risk of chronic GI blood loss, while proton pump inhibitors (PPIs) can interfere with the stomach acid needed for proper B12 and iron absorption.