Anemia Overview and Pathophysiology

Study Notes

Anemia is a deficiency in the number of red blood cells (RBCs), hemoglobin, and/or the volume of packed RBCs (hematocrit).
It's a sign of an underlying disorder, not a specific disease.
It's the most common hematologic condition.

A decrease in RBCs can be traced to three conditions:
- Impaired production of RBCs (e.g., aplastic anemia, nutritional deficiencies).
- Increased destruction of RBCs (e.g., hemolytic anemia, sickle cell anemia).
- Massive or chronic blood loss.
Some anemias are related to genetic problems.

Dietary deficiencies: Iron, folic acid, and vitamin B12 are crucial for healthy RBC production. A deficiency in any of these nutrients can cause anemia. Pernicious anemia is linked to a lack of intrinsic factor in stomach secretions, hindering vitamin B12 absorption.
Hemolysis: Hemolysis is the destruction of RBCs, leading to hemolytic anemia. This can be a congenital disorder or result from exposure to toxins.
Other causes: Thalassemia is a hereditary anemia common in certain regions (Southeast Asia, Africa, Italy, Mediterranean islands). People with thalassemia don't produce hemoglobin normally. Chronic disease can also lead to anemia.

Hemoglobin (Hgb) levels indicate anemia severity.
- Mild anemia (Hgb 10-12 g/dL): Often asymptomatic.
- Moderate anemia (Hgb 6-10 g/dL): General anemia symptoms may appear.
- Severe anemia (Hgb <6 g/dL): More severe symptoms.
Symptoms can include: Slight tachycardia, fatigue, dyspnea/shortness of breath, chest pain, and muscle pain.
Other systems affected include: pale skin and eyes, yellowing of eyes, cold extremities, low blood pressure, palpitations, rapid heart rate, angina, heart attack, enlarged spleen fatigue, dizziness, fainting.

Complete blood cell count (CBC) to measure RBCs and white blood cells (WBCs).
Hemoglobin and hematocrit levels are checked (low levels indicate anemia).
Serum iron, ferritin, and total iron-binding capacity measurements diagnose iron deficiency anemia.
Serum folate is measured if folic acid deficiency is suspected.
Bone marrow biopsy and analysis may be conducted.

Hypo-proliferative anemia: Defective RBC production. -Causes include: marrow damage, lack of RBC formation factors, or decreased erythropoietin production (e.g., from renal dysfunction, cancer, or inflammation). Nutritional deficiencies (iron, vitamin B12, folate) are specific cases of this.
Bleeding anemia: Resulting from RBC loss. -Causes include: gastrointestinal bleeding, heavy menstruation (menorrhagia), nosebleeds (epistaxis), and trauma.
Hemolytic anemia: Resulting from RBC destruction.
- Causes include: hypersplenism, drug-induced anemia, autoimmune anemia, sickle cell anemia, thalassemia.

Definition: Insufficient dietary iron for hemoglobin synthesis.
Most common type: in all ages and worldwide.
Common causes:
- Bleeding (ulcers, gastritis, inflammatory bowel disease, or gastrointestinal tumors; heavy menstruation; pregnancy without adequate iron supplementation)
- Chronic alcoholism
- Inadequate iron intake (vegetarian diets)
- Iron malabsorption (after gastrectomy, or with celiac disease)
Clinical Manifestations:
- Initially, asymptomatic
- Symptoms develop with chronic disease or severe deficiency (smooth, sore tongue, brittle nails, mouth ulcers)

Laboratory investigations (CBC, hemoglobin, hematocrit, ferritin levels) are essential to diagnose iron deficiency anemia.
Endoscopy or colonoscopy to find gastrointestinal bleeding sources.
Bone marrow biopsy may be done.

Medical management: Oral iron supplements (ferrous sulfate or ferrous gluconate).
If absorption or tolerance is poor, intravenous or intramuscular iron dextrin may be needed.

Education: Prevention is vital, particularly for menstruating and pregnant women.
Nutritional counseling: Inadequately nourished patients need advice about iron-rich foods (organ meats, beans, leafy greens, raisins, molasses).
Vitamin C: Enhances iron absorption when consumed with iron-rich foods.
Constipation: Dietary fiber reduces constipation risks when managing iron supplements.

Take iron on an empty stomach (1 hour before or 2 hours after food), especially dairy products.
To reduce gastrointestinal distress, start with a single dose, then gradually increase the dose over days.
To avoid staining teeth, use a straw to consume liquid iron preparations.