Table of Contents · 11 sections
In a nutshell. Anemia in adults is defined as Hb < 130 g/L in men and < 120 g/L in women. Classification by MCV: microcytic (MCV < 80) — IDA, thalassemias, anemia of chronic disease; normocytic (80–100) — ACD, posthemorrhagic, CRF, aplastic; macrocytic (> 100) — B₁₂/folate deficiency, MDS, alcohol. The first diagnostic step includes CBC with reticulocytes, ferritin, B₁₂, and folates. Iron deficiency anemia is the most common type (80%).
1. Definition and classification
- Men: Hb < 130 g/L.
- Non-pregnant women: Hb < 120 g/L.
- Pregnant women: Hb < 110 g/L in the 1st and 3rd trimesters, < 105 in the 2nd.
- Children: age-specific norms.
By MCV
| Type | MCV (fL) | Examples |
|---|---|---|
| Microcytic | < 80 | Iron deficiency, thalassemias, anemia of chronic disease, sideroblastic, lead poisoning |
| Normocytic | 80–100 | Acute posthemorrhagic, ACD, hemolytic, aplastic, anemia in CKD |
| Macrocytic | > 100 | B₁₂/folate deficiency, MDS, hypothyroidism, hemolysis, alcohol, drugs (methotrexate) |
By mechanism
- Impaired erythropoiesis: deficiencies (Fe, B₁₂, folates), suppression (ACD, CRF, aplastic).
- Increased loss: blood loss, hemolysis.
2. Iron deficiency anemia (IDA)
Etiology
- Chronic blood loss: menorrhagia (№1 in women), GI bleeding (№1 in men and elderly women) — rule out colorectal cancer!
- Inadequate intake: vegetarianism.
- Malabsorption: celiac disease, H. pylori, gastric resection, bariatric surgery.
- Increased demand: pregnancy, adolescence.
Clinical Practice
- Anemic syndrome: weakness, shortness of breath, tachycardia, pallor.
- Sideropenic syndrome: brittle nails (koilonychia), hair loss, angular stomatitis, glossitis, pica (perverted taste) and smell.
Diagnostics
- Microcytic hypochromic anemia: ↓ MCV, MCH, MCHC.
- Ferritin < 30 mcg/L (< 100 in inflammation) — the main marker of iron deficiency.
- ↓ serum iron, ↑ TIBC, ↓ transferrin saturation < 20%.
- Source identification: EGD, colonoscopy in men and postmenopausal women; gynecological examination in women of reproductive age.
Treatment
- Oral preparations: 100–200 mg of elemental iron daily (sulfate, fumarate, gluconate).
- Alternative — every other day, 100 mg — increases absorption due to ↓ hepcidin (Moretti 2015).
- Take on an empty stomach with vitamin C; avoid tea, calcium, PPIs.
- Monitoring: reticulocytes ↑ on days 5–7; Hb ↑ by 10 g/L in 2 weeks.
- Continue for 3–6 months after normalization of Hb to replenish stores.
- IV preparations (carboxymaltose, derisomaltose) — for intolerance, malabsorption, CHF, CKD, post-bariatric surgery.
3. Vitamin B₁₂ deficiency anemia
Causes
- Pernicious anemia (autoimmune atrophic gastritis, Abs to parietal cells and intrinsic factor).
- Gastrectomy, atrophic gastritis in the elderly.
- Resection/involvement of the terminal ileum (Crohn's disease).
- Metformin, PPIs, H₂-blockers — chronic reduction in absorption.
- Vegetarianism/veganism without supplements.
- Parasites (Diphyllobothrium latum).
Clinical Practice
- Macrocytic anemia + pancytopenia in severe deficiency.
- Hunter's glossitis (crimson "lacquered" tongue).
- Neurological: funicular myelosis (paresthesias, ataxia, ↓ deep sensation, memory impairment).
Diagnostics
- MCV > 100, neutrophil hypersegmentation (> 5 segments).
- ↓ serum B₁₂; ↑ methylmalonic acid and homocysteine — early markers.
- Abs to intrinsic factor — for pernicious anemia.
- Rule out concomitant iron deficiency (can mask macrocytosis).
Treatment
- Cyanocobalamin 500–1000 mcg IM every other day for 2 weeks, then 1 time/week for 1 month, then 1 time/month for life (in pernicious anemia).
- For nutritional causes — oral B₁₂ 1000–2000 mcg/day may be sufficient.
- Neurological symptoms — early treatment (up to 6 months from onset) offers a chance of full recovery.
4. Folic acid deficiency anemia
- Causes: dietary deficiency, alcoholism, pregnancy, hemolysis, drugs (methotrexate, phenytoin, trimethoprim).
- Clinical presentation: macrocytic anemia without neurological symptoms (unlike B₁₂ deficiency).
- Diagnostics: ↓ serum and RBC folate, ↑ homocysteine, normal methylmalonic acid.
- Treatment: folic acid 1–5 mg/day for 1–4 months. B₁₂ deficiency must be ruled out (otherwise it will worsen neurology!).
5. Anemia of chronic disease (ACD)
- Occurs in infections, IBD, oncology, CHF, autoimmune diseases, CKD.
- Normocytic/microcytic, hypoproliferative.
- Hepcidin ↑ → blockade of Fe absorption and release from stores.
- Diagnostics: ferritin normal or ↑, transferrin saturation ↓, CRP ↑.
- Treatment of the underlying disease; in CKD — erythropoiesis-stimulating agents (ESAs) + iron supplements.
6. Hemolytic anemias
| Type | Examples | Key |
|---|---|---|
| Hereditary membranopathies | Spherocytosis | Coombs test (–), eosin-5-maleimide |
| Hemoglobinopathies | Sickle cell disease, thalassemias | Hb electrophoresis |
| Enzymopathies | G6PD deficiency | Hemolysis after fava beans, sulfonamides |
| Autoimmune | Warm AIHA (IgG), cold agglutinin disease (IgM) | Coombs test (+) |
| Microangiopathic | TTP, HUS, HELLP, DIC | Schizocytes, thrombocytopenia |
| Mechanical | Prosthetic valves | Schizocytes |
General features: ↑ indirect bilirubin, ↓ haptoglobin, ↑ LDH, reticulocytosis, hemoglobinuria.
7. Aplastic anemia
- Pancytopenia with hypocellular bone marrow.
- Causes: viruses (hepatitis, parvovirus), drugs (chloramphenicol, carbamazepine), radiation, idiopathic.
- Treatment: immunosuppression (ATG + cyclosporine) or allogeneic HSCT in young patients.
8. Anemia in CKD
- Decreased erythropoietin production in the kidneys.
- Therapy: iron supplements (IV preferred) + ESAs (epoetin alfa/beta, darbepoetin).
- HIF inhibitors (roxadustat) — a new class of oral drugs.
- Target Hb 100–115 g/L (avoid > 120 due to ↑ CVD events).
9. Diagnostic algorithm
- CBC with RBC indices and reticulocytes.
- Use MCV to guide the diagnostic workup.
- Iron panel (ferritin, TIBC, transferrin saturation).
- B₁₂, folates in case of macrocytosis.
- LDH, haptoglobin, indirect bilirubin — if hemolysis is suspected; Coombs test.
- If etiology is unclear — sternal puncture and trephine biopsy.
10. Specifics in pregnant women
- Physiological hemodilution (ΔHb ~20 g/L).
- Prevention: folic acid 400–800 mcg/day from the pre-conception period up to 12 weeks; iron 30–60 mg of elemental iron starting from the 2nd trimester in case of risk factors.
- Treatment of IDA: oral iron, IV — starting from the 2nd trimester in case of intolerance/severe deficiency.
11. FAQ
Why prescribe iron every other day?
Daily administration increases hepcidin → decreases absorption of the next dose. The "every other day" regimen increases cumulative absorption and reduces gastrointestinal side effects.
Can IV iron be administered immediately?
Yes, in CHF, CKD, IBD, intolerance, after bariatric surgery, in pregnant women in the 3rd trimester when oral therapy cannot correct the deficit quickly enough.
Why is it important to search for the source of IDA in men?
In men and postmenopausal women, IDA is frequently a marker of colorectal cancer. EGD + colonoscopy are mandatory.
What are the risks of treating with folates without checking B₁₂?
Correction of hematological symptoms while neurological damage from B₁₂ deficiency continues to progress. Always check B₁₂ before folate therapy.
When to suspect thalassemia?
Microcytic anemia with normal/elevated ferritin, family history (Mediterranean region, Caucasus). Diagnosis — Hb electrophoresis.
See also: Blood: formed elements · Hemostasis · Anticoagulants · IBD · Hematology catalog