Common causes of low hemoglobin in older adults
For many years, a mild decline in hemoglobin was considered a normal consequence of aging. However, medical experts now recognize that this is a sign of an underlying health problem that requires proper diagnosis and treatment. The causes are often multifactorial and can be classified into several main categories.
Nutritional deficiencies
Nutrient deficiencies are a significant and often reversible cause of anemia in the elderly. The body needs several key vitamins and minerals to produce healthy red blood cells and hemoglobin. Deficiencies can arise from poor diet, malabsorption issues, or other medical conditions.
Iron deficiency anemia
Iron deficiency is one of the most common causes, often resulting from chronic, slow-leaking blood loss, particularly from the gastrointestinal (GI) tract. Conditions that can cause this include:
- Peptic ulcers
- Chronic gastritis
- Colorectal cancer
- The use of nonsteroidal anti-inflammatory drugs (NSAIDs)
Vitamin B12 and folate deficiencies
Deficiencies in vitamin B12 or folate can lead to megaloblastic anemia, where red blood cells are larger than normal but not fully functional. Older adults are particularly susceptible to B12 deficiency due to a decreased ability to absorb it from food, often caused by atrophic gastritis or pernicious anemia.
Anemia of chronic disease (ACD) or inflammation
Anemia of chronic disease (ACD), also known as anemia of inflammation, is the most common form of anemia in the elderly. It is not caused by a lack of iron in the body but rather by the body's inability to use the iron effectively due to chronic inflammation. This can be a complication of many long-term illnesses:
- Infections (e.g., chronic UTIs, osteomyelitis)
- Autoimmune diseases (e.g., rheumatoid arthritis, lupus)
- Inflammatory bowel diseases (e.g., Crohn's disease, ulcerative colitis)
- Cancers
- Heart failure
Chronic kidney disease (CKD)
The kidneys produce a hormone called erythropoietin (EPO), which signals the bone marrow to produce red blood cells. As kidney function declines with age and chronic conditions like diabetes and hypertension, EPO production can decrease, leading to anemia. This is a common and predictable complication of CKD.
Bone marrow disorders
The bone marrow is responsible for producing all blood cells. Disorders that affect the bone marrow can therefore impact hemoglobin levels. Myelodysplastic syndromes (MDS) are a group of blood cancers where the bone marrow produces abnormal, immature blood cells. They are more common in older adults and can present as an unexplained anemia.
Gastrointestinal bleeding
As mentioned under iron deficiency, GI bleeding is a major cause of blood loss and subsequent anemia. Sources of bleeding can be difficult to detect and may include ulcers, diverticulosis, or cancer. The blood loss can be slow and chronic, leading to anemia over time before any visible signs appear.
Medications
Many medications that older adults take for other chronic conditions can have side effects that affect red blood cell production or survival. These can include NSAIDs, certain antibiotics, and some cancer treatments like chemotherapy and radiation. It is important to review a senior's full medication list when investigating a low hemoglobin level.
Unexplained anemia of aging (UAA)
In about one-third of elderly patients with anemia, no clear cause can be identified despite extensive testing. This is termed unexplained anemia of aging (UAA). Research suggests UAA may be linked to subclinical inflammation, hormonal changes (such as lower testosterone in men), or subtle declines in bone marrow function.
Comparison of ACD vs. Iron Deficiency Anemia
| Feature | Anemia of Chronic Disease (ACD) | Iron Deficiency Anemia (IDA) |
|---|---|---|
| Underlying Cause | Chronic inflammation from infection, autoimmune disease, or cancer. | Chronic blood loss (often GI), inadequate intake, or malabsorption. |
| Iron Stores | Iron stores are typically normal or increased, but the body cannot access them efficiently due to inflammation. | Iron stores are depleted due to loss or insufficient intake. |
| Serum Ferritin | Normal or elevated (since ferritin is an acute-phase reactant). | Low (the most sensitive marker for true iron deficiency). |
| Red Blood Cell Size | Usually normocytic (normal size), though can sometimes be microcytic (small). | Microcytic (small). |
| Treatment | Addressing the underlying chronic condition. Iron supplementation is often ineffective. | Iron supplementation (oral or intravenous) and treating the source of blood loss. |
Symptoms and diagnosis
It's important to recognize that symptoms of anemia in the elderly can be subtle and often mistaken for normal signs of aging, such as fatigue or weakness. A thorough medical evaluation, including a complete blood count (CBC) and other targeted tests, is necessary for an accurate diagnosis.
Common signs and symptoms of low hemoglobin in older adults include:
- Persistent fatigue and lack of energy
- Unexplained weakness
- Shortness of breath, especially with exertion
- Dizziness or lightheadedness
- Pale skin, especially visible in the lining of the eyes (conjunctiva)
- Rapid or irregular heartbeat
- Cold hands and feet
The importance of accurate diagnosis
Identifying the correct cause of low hemoglobin is crucial for effective treatment. A misdiagnosis can lead to inappropriate and ineffective interventions, such as prescribing iron supplements for ACD, which will not address the root cause. A proper workup can prevent complications and improve quality of life.
Conclusion: A proactive approach to senior health
While a decline in hemoglobin is common with age, it is not an inevitable or harmless part of the aging process. By recognizing the diverse factors that can contribute to why would hemoglobin be low in the elderly, from nutritional issues to chronic conditions and medication side effects, caregivers and healthcare providers can ensure a proactive and accurate approach to diagnosis and treatment. Addressing the underlying cause can significantly improve a senior's energy levels, mobility, and overall well-being. Always consult with a qualified healthcare provider for a thorough evaluation and personalized care plan. For more information, the American Academy of Family Physicians offers valuable resources on this topic. Anemia in Older Adults - AAFP.
