Haematology Lecture on Anaemias

Haematology Lecture Notes

• The lecture, titled "Anaemias," was presented on October 29, 2024.
• The lecturer was Mohammed Ismael Dawood, an Assistant Professor in the Department of Medicine at the University of Fallujah, College of Medicine.
• The lecture's stage was 5th.
• The lecture covered three basic learning objectives
  • Iron Deficiency anaemia
  • Anaemia of chronic disease
  • Megaloblastic Anaemia

Anaemias Overview

• Approximately 30% of the global population is anemic, with iron deficiency being the cause in half of those cases.
• The body's physiological response to anemia involves increasing 2,3-DPG levels to facilitate oxygen unloading in tissues.
• This heightened activity leads to a hyperdynamic circulation, recognizable by a rapid pulse and potential heart murmurs.

Iron Deficiency Anemia

• Iron deficiency anemia occurs when iron absorption cannot keep pace with iron loss.
• Common causes include:
  • Blood loss (GI tract bleeding, especially in men >40 and postmenopausal women due to colorectal or gastric malignancies, peptic ulcers, inflammatory bowel diseases, diverticulitis or angiodysplasia);
  • Worldwide, parasites like hookworms and schistosomiasis;
  • Menstrual bleeding (younger women);
  • Pregnancy;
  • Use of aspirin or NSAIDs exacerbating GI bleeding.
• Other factors include:
  • Malabsorption (gastric acid is required to dissolve iron from food for absorption; deficiency might arise from proton pump inhibitors or prior gastric surgery, and conditions like coeliac disease impacts the small intestine's ability to absorb iron);
  • Increased physiological demands (puberty and pregnancy).

Iron Deficiency Anemia: Clinical Features

• Glossitis (smooth, sore, red tongue)
• Koilonychia (spoon-shaped nails)
• Angular stomatitis (sores/cracks at mouth corners)
• Alopecia (hair loss)
• Pica (unusual food cravings, like clay or ice).

Iron Deficiency Anemia: Investigations

• Blood film shows microcytic hypochromic red cells (low MCV and MCH).
• Low plasma ferritin levels; however, elevated ferritin levels might occur due to liver disease or inflammation.
• Helpful investigations include:
  • Transferrin saturation (<16%)
  • Elevated soluble transferrin receptor.

Anaemia of Chronic Disease

• This type of anemia is often associated with chronic infections, inflammation, and cancer.
• A key regulatory protein, hepcidin, inhibits iron export from cells; despite high iron stores.
• Characteristic features include: diminished total iron binding capacity (TIBC), and low/normal soluble transferrin receptor.
• The anemia is usually normocytic and normochromic, but reduced MCV may occur in long-standing inflammation.

Investigations to Differentiate Anemia Types

• A comparison table (refer to page 14 of notes) highlights how different markers vary across iron deficiency anemia, and anaemia of chronic inflammation cases.

Megaloblastic Anemia

• This anemia results from vitamin B12 or folate deficiency, which are needed for DNA synthesis.
• The anemia presents with large, immature red blood cells (megaloblasts).
• Mature red blood cells often have an oval shape, and white blood cells exhibit hypersegmented nuclei.
• Severe cases can lead to pancytopenia.
• Bone marrow examination shows increased cellularity and megaloblastic changes.

Vitamin B12 Deficiency

• The average diet contains more than needed, mainly from meat, eggs, and milk.
• Gastric enzymes release vitamin B12, which then bonds with R protein.
• Intrinsic factor, a different protein, is then involved in releasing vitamin B12 from R protein as gastric emptying occurs.
• Absorption occurs in the terminal ileum and transport is facilitated by transcobalamin II (produced by the liver).
• Liver vitamin B12 stores typically last for 3 years; deficiency may take a while to manifest.
• Neurological manifestations include peripheral neuropathy, subacute combined degeneration of the spinal cord (posterior columns affecting proprioception and vibration sense; corticospinal tract damage causing upper motor neuron signs), dementia, and optic atrophy.

Causes of Vitamin B12 Deficiency

• Dietary deficiency (very rare).
• Gastric factors (gastric surgery, or conditions impairing gastric acid and intrinsic factor production/secretion)

Pernicious Anemia

• An autoimmune condition; Atrophy of the gastric mucosa, and loss of the parietal cells cause intrinsic factor deficiency and vitamin B12 malabsorption.
• Often associated with other autoimmune conditions (e.g., Hashimoto's thyroiditis, Graves' disease, vitiligo, and Addison's disease).
• Diagnosed with the Schilling test (formerly but less so, with the advent of autoantibody tests, radioactive tracers being less used).

Small Bowel Factors related to vitamin B12 deficiency

• Terminal ileal disease (e.g., Crohn's disease) or ileal resection impairs vitamin B12 absorption.
• Motility disorders causing bacterial overgrowth can compete for free vitamin B12 leading to deficiency.

Megaloblastic Anemia: Clinical Features

• General signs and symptoms (malaise, breathlessness, paraesthesias, etc.), or skin pigmentation, heart failure, or fever might be present.
• Specific signs include smooth tongue, angular cheilosis, or vitiligo.

Folate Deficiency

• Dietary sources include leafy green vegetables, fruits, liver, and kidneys.
• Deficiency can develop within weeks, as total body folate stores are small.
• Causes include poor dietary intake, malabsorption, increased demand (pregnancy, hemolysis), and drug interactions (like phenytoin, oral contraceptives, or methotrexate).

Management

• Iron Deficiency: Oral iron supplementation (ferrous sulfate 200 mg three times a day) for 3-6 months, alongside treatment of the underlying cause. Hemoglobin (Hb) should increase by 10 g/L every 7–10 days.
• B12 Deficiency: Treatment involves IM injections of hydroxycobalamin (1000 μg, 6 doses, 2-3 days apart), followed by lifelong maintenance doses (1000 µg every 3 months). Neurology improvement takes 6-12 months.
• Folate Deficiency: Oral folic acid (5 mg daily). Also used as prophylactic measure in pregnancy or chronic conditions with reduced red blood cell lifespan (e.g., autoimmune hemolytic anemia or hemoglobinopathies).

Megaloblastic Anemia Investigations

• A table (page 27/notes) displays related investigations—hemoglobin, mean cell volume, erythrocyte count, blood film (oval macrocytosis; poikilocytosis), reticulocyte count, bone marrow, serum ferritin, or plasma lactate dehydrogenase.

Key takeaway:

• Careful consideration of clinical presentation, associated conditions, and relevant investigations are key in differentiating types of anemia.

Explore the key concepts from the haematology lecture on anaemias including iron deficiency anaemia, anaemia of chronic disease, and megaloblastic anaemia. Understand the physiological responses and prevalence of anaemia globally. This quiz covers the important aspects of these medical conditions as presented by Professor Mohammed Ismael Dawood.