Anemia is a condition characterized by a decrease in the number of red blood cells or hemoglobin in the blood, leading to reduced oxygen-carrying capacity. This condition affects approximately 10% of adults in developed countries and up to 40% in developing regions. Anemia is important because it can significantly impact a person’s quality of life, causing fatigue, weakness, and other symptoms. It is often a sign of an underlying health issue that needs to be addressed.
Oxygen delivery in the body
The human body needs oxygen to produce energy and support cellular functions. Oxygen enters the body through the lungs when we breathe. It then binds to hemoglobin molecules in red blood cells, transporting it through the bloodstream to tissues and organs. Hemoglobin is a protein that contains iron and binds oxygen molecules, allowing red blood cells to carry oxygen efficiently. Iron is essential for hemoglobin synthesis; without sufficient iron, hemoglobin cannot function properly. Once delivered, oxygen is used in cellular respiration to generate energy. Changes in red blood cells, such as a decrease in their number or hemoglobin content, lead to decreased oxygen delivery, causing symptoms of anemia.
Symptoms and signs of anemia in an adult
Symptoms of anemia can vary depending on its severity and underlying cause but commonly include fatigue, weakness, shortness of breath, dizziness, pale or yellowish skin, and an irregular heartbeat. Other signs may include cold hands and feet, headache, and chest pain.
How is anemia diagnosed?
Anemia is diagnosed through a series of blood tests. The complete blood count (CBC) measures hemoglobin levels, hematocrit, and the number of red blood cells. Additional tests, such as a reticulocyte count, peripheral smear, and serum ferritin, help determine the cause of anemia. The results are reported as numerical values with reference ranges provided for interpretation. Low hemoglobin or hematocrit indicates anemia and the specific type of anemia can be identified based on red blood cell size and shape.
Here’s a guide to understanding the common tests and their results:
Complete blood count (CBC)
- Hemoglobin (Hb): Measures the amount of hemoglobin in the blood. Low levels indicate anemia. Normal ranges: 13.8-17.2 g/dL for men, 12.1-15.1 g/dL for women.
- Hematocrit (Hct): The proportion of blood volume occupied by red blood cells. Low levels indicate anemia. Normal ranges: 40.7-50.3% for men, 36.1-44.3% for women.
- Red blood cell (RBC) Count: The number of red blood cells in a volume of blood. Low counts indicate anemia. Normal ranges: 4.7-6.1 million cells/μL for men, 4.2-5.4 million cells/μL for women.
- Mean corpuscular volume (MCV): The average size of red blood cells. Low MCV indicates microcytic anemia (e.g., iron deficiency), and high MCV indicates macrocytic anemia (e.g., vitamin B12 or folate deficiency). Normal range: 80-100 fL.
- Mean corpuscular hemoglobin (MCH): The average amount of hemoglobin per red blood cell. Low MCH indicates hypochromic anemia. Normal range: 27-33 pg.
- Mean corpuscular hemoglobin concentration (MCHC): The average hemoglobin concentration in red blood cells. Low MCHC indicates hypochromic anemia. Normal range: 32-36 g/dL.
- Red cell distribution width (RDW): Measures the variation in red blood cell size. High RDW can indicate mixed anemia or evolving anemia. Normal range: 11.5-14.5%.
Reticulocyte count
- Measures the number of young red blood cells in the blood. A low reticulocyte count indicates inadequate red blood cell production, whereas a high count indicates increased red blood cell production in response to anemia. Normal range: 0.5-2.5%.
Peripheral blood smear
- Examines the shape, size, and appearance of red blood cells under a microscope. Abnormal shapes or sizes can indicate specific types of anemia (e.g., sickle cells in sickle cell anemia and large cells in megaloblastic anemia).
Serum ferritin
- Measures the stored iron in the body. Low ferritin levels indicate iron deficiency anemia. Normal range: 24-336 ng/mL for men, 11-307 ng/mL for women.
Serum iron and total iron binding capacity (TIBC)
- Serum Iron: Measures the amount of iron in the blood. Low levels indicate iron deficiency. Normal range: 60-170 mcg/dL.
- TIBC: Measures the blood’s capacity to bind iron with transferrin. High TIBC indicates iron deficiency. Normal range: 240-450 mcg/dL.
- Transferrin Saturation: The percentage of transferrin that is saturated with iron. Low levels indicate iron deficiency. Normal range: 20-50%.
Vitamin B12 and folate levels
- Vitamin B12: Low levels indicate vitamin B12 deficiency anemia. Normal range: 200-900 pg/mL.
- Folate: Low levels indicate folate deficiency anemia. Normal range: 2.7-17.0 ng/mL.
Erythropoietin level
- Measures the hormone that stimulates red blood cell production. Low levels in the context of anemia may indicate chronic kidney disease. Normal range: 2.6-18.5 mU/mL.
Lactate dehydrogenase (LDH) and haptoglobin
- LDH: Elevated levels can indicate hemolysis (red blood cell destruction). Normal range: 140-280 U/L.
- Haptoglobin: Low levels can indicate hemolysis. Normal range: 30-200 mg/dL.
Bilirubin
- Measures the byproduct of red blood cell breakdown. Elevated levels can indicate hemolysis. Normal range: 0.1-1.2 mg/dL.
Direct antiglobulin test (Coombs test)
- Detects antibodies against red blood cells. A positive test indicates autoimmune hemolytic anemia.
What is the most common cause of anemia in adults?
Iron deficiency
Iron deficiency anemia is the most common cause of anemia in adults. It occurs when the body lacks sufficient iron to produce hemoglobin. This condition can result from inadequate dietary intake, chronic blood loss (e.g., from gastrointestinal bleeding), or increased iron requirements (e.g., during pregnancy). Iron deficiency anemia often presents with fatigue, pallor, and a craving for non-nutritive substances like ice or clay (pica). Diagnosis involves measuring serum ferritin and transferrin saturation. Treatment includes iron supplementation and addressing the underlying cause of iron deficiency.
Other common medical conditions associated with anemia in adults
Chronic kidney disease
In chronic kidney disease, reduced erythropoietin production reduces red blood cell production. Erythropoietin is a hormone the kidneys produce that stimulates the bone marrow to produce red blood cells. Symptoms include fatigue, swelling, and changes in urination. Diagnosis involves blood tests showing elevated creatinine and decreased glomerular filtration rate (GFR). Treatment includes erythropoiesis-stimulating agents and managing kidney disease.
Vitamin B12 deficiency
In vitamin B12 deficiency, impaired DNA synthesis affects red blood cell production, causing megaloblastic anemia. Vitamin B12 is essential for the formation of red blood cells and the maintenance of the nervous system. Symptoms include numbness, cognitive changes, and glossitis. Diagnosis involves low serum B12 levels and high mean corpuscular volume (MCV). Treatment includes B12 supplementation.
Folate deficiency
Similar to B12 deficiency, folate deficiency leads to megaloblastic anemia. Folate is necessary for DNA synthesis and red blood cell formation. Symptoms are similar to those of B12 deficiency but without neurological symptoms. Diagnosis involves low serum folate levels and high MCV. Treatment includes folate supplementation.
Gastrointestinal bleeding
Chronic blood loss in the gastrointestinal tract from ulcers or cancers leads to iron deficiency anemia. Symptoms include fatigue and melena. Diagnosis involves endoscopy and stool tests for occult blood. Treatment includes addressing the source of bleeding and iron supplementation.
Anemia of chronic disease
In anemia of chronic disease, high levels of inflammatory cytokines in the blood affect iron metabolism and red blood cell production. Chronic diseases associated with this type of anemia include rheumatoid arthritis, chronic infections, and cancer. Symptoms include those of the underlying chronic disease. Diagnosis involves normal or increased ferritin with low iron and transferrin saturation. Treatment focuses on managing the chronic condition.
Thalassemia
Thalassemia is a genetic disorder leading to abnormal hemoglobin production. Symptoms include fatigue, jaundice, and skeletal deformities. Diagnosis involves hemoglobin electrophoresis showing abnormal hemoglobin variants. Treatment includes regular blood transfusions and chelation therapy.
Sickle cell disease
Sickle cell disease is an inherited condition causing abnormal hemoglobin that leads to red blood cell sickling. Symptoms include pain crises, anemia, and organ damage. Diagnosis involves hemoglobin electrophoresis showing sickle hemoglobin. Treatment includes pain management, hydroxyurea, and blood transfusions.
Hypothyroidism
Reduced thyroid hormone levels lead to decreased red blood cell production. Symptoms include fatigue, weight gain, and cold intolerance. Diagnosis involves elevated thyroid-stimulating hormone (TSH) and low thyroid hormone levels. Treatment includes thyroid hormone replacement.
Hemolytic anemia
In hemolytic anemia, increased red blood cell destruction due to various causes such as autoimmune disorders, infections, and certain medications. Symptoms include jaundice, dark urine, and splenomegaly. Diagnosis involves low haptoglobin, high lactate dehydrogenase (LDH), and high bilirubin. Treatment depends on the underlying cause.
Bone marrow disorders
A variety of bone marrow disorders, including leukemia and myelodysplastic syndrome, affect red blood cell production. Symptoms include fatigue, infections, and bleeding. Diagnosis involves a bone marrow biopsy showing abnormal cells. Treatment varies based on the specific disorder.
Less common but serious medical conditions associated with anemia in adults
Aplastic anemia
In aplastic anemia, bone marrow failure leads to pancytopenia, a condition where all blood cell types (red cells, white cells, and platelets) are decreased. Symptoms include fatigue, infections, and bleeding. Conditions causing aplastic anemia include autoimmune diseases, certain medications, and viral infections. Diagnosis involves bone marrow biopsy showing hypocellularity. Treatment includes immunosuppressive therapy or bone marrow transplant.
Myelofibrosis
Myelofibrosis means scaring or fibrosis of the bone marrow. The loss of normal bone marrow tissue disrupts blood cell production. Symptoms include fatigue, splenomegaly, and night sweats. Diagnosis involves bone marrow biopsy showing fibrosis. Treatment includes medication to manage symptoms and stem cell transplant.
Paroxysmal nocturnal hemoglobinuria
Paroxysmal nocturnal hemoglobinuria is a genetic disorder causing red blood cell destruction. Symptoms include dark urine, abdominal pain, and thrombosis. Conditions associated with this cause include bone marrow failure syndromes and autoimmune disorders. Diagnosis involves flow cytometry showing deficient GPI-anchored proteins. Treatment includes eculizumab and supportive care.
Hemolytic uremic syndrome
In hemolytic uremic syndrome, microvascular disease leads to red blood cell destruction and kidney failure. Symptoms include bloody diarrhea, fatigue, and decreased urine output. Conditions associated with this cause include infections like E. coli and genetic predispositions. Diagnosis involves blood tests showing hemolysis and renal impairment. Treatment includes supportive care and sometimes plasmapheresis.
Pure red cell aplasia
Pure red cell aplasia means selective bone marrow failure affecting only red blood cells. Symptoms include fatigue and pallor. Conditions causing this anemia include thymoma, viral infections, and autoimmune diseases. Diagnosis involves bone marrow biopsy showing erythroid hypoplasia. Treatment includes immunosuppressive therapy or treatment of underlying conditions.
Vitamin B6 deficiency
Vitamin B6 deficiency affects hemoglobin synthesis because it is a cofactor in hemoglobin production. Symptoms include irritability, depression, and glossitis. Low serum vitamin B6 levels confirm the diagnosis. Treatment includes B6 supplementation.
Copper deficiency
Copper deficiency affects iron metabolism and red blood cell production. Symptoms include fatigue, neuropathy, and leukopenia. Diagnosis involves low serum copper levels. Treatment includes copper supplementation.
Lead poisoning
Lead poisoning interferes with hemoglobin synthesis. Symptoms include abdominal pain, cognitive impairment, and anemia. Diagnosis involves elevated blood lead levels. Treatment includes chelation therapy.
Autoimmune hemolytic anemia
In autoimmune hemolytic anemia, the immune system attacks red blood cells. Conditions associated with this cause include lupus, lymphomas, and certain infections. Symptoms include fatigue, jaundice, and dark urine. Diagnosis involves a positive direct antiglobulin test (Coombs test). Treatment includes corticosteroids and immunosuppressive therapy.
Thrombotic thrombocytopenic purpura
In thrombotic thrombocytopenic purpura, microvascular disease leads to red blood cell destruction and platelet aggregation. Conditions associated with this cause include autoimmune disorders, pregnancy, and certain medications. Symptoms include fatigue, petechiae, and neurologic symptoms. Diagnosis involves blood tests showing hemolysis and thrombocytopenia. Treatment includes plasmapheresis and immunosuppressive therapy.
Clues to aid in the differential diagnosis
1. Fatigue and pallor suggest anemia of chronic disease or iron deficiency anemia.
2. Jaundice and dark urine indicate hemolytic anemia or sickle cell disease.
3. Neurological symptoms suggest vitamin B12 deficiency or lead poisoning.
4. Splenomegaly points to thalassemia, myelofibrosis, or hemolytic anemia.
5. Gastrointestinal symptoms indicate iron deficiency anemia from chronic bleeding or lead poisoning.
6. Glossitis and cheilitis suggest vitamin B12, folate, or iron deficiency.
7. Bone pain or fractures may indicate sickle cell anemia, myeloma, or bone marrow disorders.
8. Petechiae and bruising suggest aplastic anemia or thrombotic thrombocytopenic purpura.
9. Abdominal pain and dark urine in paroxysmal nocturnal hemoglobinuria.
10. Night sweats and weight loss in myelofibrosis or leukemia.
Advice for patients
Treatment and management of anemia depend on the underlying cause. General advice includes ensuring a balanced diet rich in iron, vitamin B12, and folate. Iron supplements may be recommended for iron deficiency anemia. Addressing chronic diseases, such as kidney disease or inflammatory conditions, is also important. Regular monitoring and follow-up with a healthcare provider are essential to manage symptoms and prevent complications. In cases of severe anemia, blood transfusions or bone marrow transplant may be necessary.
Iron supplementation tips
Iron supplementation is a common treatment for iron deficiency anemia. Here are some tips to ensure effective and safe iron supplementation:
Choose the right type of iron supplement
- Ferrous sulfate, ferrous gluconate, and ferrous fumarate are common forms of iron supplements. Ferrous sulfate is often recommended due to its high bioavailability.
- Consult with your healthcare provider to determine the best type and dosage for your specific needs.
Take iron supplements on an empty stomach
- Iron is best absorbed when taken on an empty stomach, about an hour before meals or two hours after meals.
- However, if stomach upset occurs, taking it with a small amount of food may help, but avoid dairy products, coffee, and tea which can inhibit absorption.
Enhance absorption with vitamin C
- Vitamin C can enhance iron absorption. Take your iron supplement with a glass of orange juice or a vitamin C supplement.
Avoid foods and drinks that inhibit iron absorption
- Calcium, coffee, tea, and certain whole grains can inhibit iron absorption. Avoid consuming these around the time you take your iron supplement.
Be aware of potential side effects
- Common side effects of iron supplements include constipation, diarrhea, nausea, and stomach cramps. If these occur, talk to your healthcare provider. They may recommend a different form of iron or a lower dose.
Monitor your progress
- Regular blood tests are important to monitor your hemoglobin and iron levels. This will help ensure that the supplementation is effective and allow adjustments to be made if necessary.
Follow the prescribed duration
- Iron supplementation should be continued for the duration recommended by your healthcare provider, even if you start feeling better. This ensures that your iron stores are adequately replenished.
Store iron supplements safely
- Keep iron supplements out of reach of children. Accidental overdose of iron supplements can be very dangerous for children.
Maintain a balanced diet
- Along with supplementation, consume iron-rich foods such as lean meats, beans, lentils, fortified cereals, and leafy green vegetables. This helps in maintaining adequate iron levels in the long term.
Talk to your doctor
- Inform your doctor about any other medications or supplements you are taking, as some can interfere with iron absorption or effectiveness. Regular communication ensures optimal treatment and management.
Summary
Anemia in adults is a common condition with various causes ranging from nutritional deficiencies to chronic diseases and genetic disorders. Understanding the underlying cause is essential for effective treatment and management. Symptoms can significantly impact quality of life, but with appropriate diagnosis and intervention, many forms of anemia can be effectively managed.
Selected references
- Stauder, R., Thein, S. L., & Campo, E. (2018). Anemia at older age: etiologies, clinical implications, and management. Blood, 131(5), 505-514. doi:10.1182/blood-2017-07-746919.
- Killip, S., Bennett, J. M., & Chambers, M. D. (2007). Iron deficiency anemia. American Family Physician, 75(5), 671-678.
- Cappellini, M. D., Comin-Colet, J., de Francisco, A., Dignass, A., Doehner, W., Lam, C. S. P., … & Walker, H. (2017). Iron deficiency across chronic inflammatory conditions: International expert opinion on definition, diagnosis, and management. American Journal of Hematology, 92(10), 1068-1078. doi:10.1002/ajh.24820.