Anemia Investigation and Clinical Application

Anemia Investigation and Clinical Application

• Anemia is a condition of reduced red blood cell count, leading to oxygen delivery deficiency.
• Bone marrow (BM) examination and flow cytometry (FC) aid in anemia diagnosis.
• BM examination indications include cytopenia, leukemia, lymphoma, or suspected infections.
• BM aspiration involves collecting bone marrow cells using a needle, while biopsy uses a core needle for deeper tissue analysis.
• Sites for BM aspiration include the posterior superior iliac spine and sternum (in children).
• BM examination is vital for classifying anemia types, evaluating cell morphology, and analyzing myeloid-erythroid ratios.
• Flow cytometry helps in analyzing cell characteristics like size and granularity, nuclear complexity, surface antigens, and cytoplasmic antigens.

Bone Marrow Examination

• BM examination is crucial for identifying cell types and their characteristics, determining cell composition, evaluating the cellularity (ratio of cells and stroma), and identifying potential infiltrates or mutations.
• Core biopsy of bone marrow is important for analyzing fibrosis and the degree of cellularity.

Bone Marrow Biopsy

• It's essential for identifying tissue histology, cellularity degrees (hypocellular or hypercellular), and features like fibrosis, infiltration, or infection.
• A dry tap, or absence of aspirate, is caused by cortical thickness, fibrosis in the bone marrow, or infiltration in the marrow, making biopsy more useful in these cases.

Indications of BM Examination

• Diagnosis of cytopenias (pancytopenia, aplastic anemia, megaloblastic anemia, myelodysplastic syndrome, and BM metastasis) are typical cases for BM exam.
• Diagnosis of leukemia, lymphoma and staging are also indications.
• Unexplained splenomegaly, infections(PUO, TB, kala-azar), storage diseases (Gaucher disease).
• Assessment of iron stores/sideroblastic anemia and monitoring disease response/MRD.

Contraindications of BM Examination

• Hemophilia, severe disseminated intravascular coagulopathy (DIC) may cause hemorrhage
• Thrombocytopenia, is not a contraindication—correct values may allow for procedure.

Adverse Effects

• No significant adverse effects

"Dry Tap" in BM Examination

• "Dry tap" occurs when no aspirate is collected, which can be caused by technical issues (needle issues), fibrosis, hairy cell leukemia, BM metastases, and leukemias (with blast cells).

When is Biopsy Most Useful?

• More useful than aspiration in aplastic anemia/MDS/myelofibrosis/metastatic carcinoma, lymphoma staging, suspected granulomas, or "dry taps."

Flow Cytometry

• Utilizes a laser light source to assess the physical characteristics of cells and determine antigenic features.
• Classifies cells based on scattered light intensity, aiding in the diagnosis of leukemia, lymphoma, immunodeficiency disorders, treatment monitoring, and prognosis.

Types of Anemia Based on MCV

• Microcytic anemia (MCV < 76 fl) : Iron deficiency anemia, thalassemia trait, anemia of chronic disease (ACD), congenital sideroblastic anemia, lead poisoning.
• Macrocytic anemia (MCV > 100 fl) : B12 or folate deficiency, MDS (myelodysplastic syndrome), hemolytic anemia, liver disease, alcohol use, hypothyroidism.
• Normocytic anemia (MCV 76-100 fl): Secondary anemia, renal failure, rheumatoid arthritis, acute blood loss.

Anemia Classification Based on Reticulocyte Count

• Reticulocytosis (increased reticulocytes) indicates increased bone marrow activity, usually due to hemolysis, acute bleeding, or following hematinics.
• Reticulocytopenia (decreased reticulocytes) indicates low bone marrow activity, as seen in cases like aplastic anemia or following chemotherapy.

Iron Metabolism & Distribution

• Iron exists in the body as ferrous (active) or ferric (inactive) forms.
• Iron is absorbed from the diet and controlled by intestinal absorption, which is influenced by dietary content (e.g., heme vs. non-heme iron; phytate, tannins, alkalinity) and factors like inflammation, IDA, blood loss, pregnancy, hypoxia.
• Iron is stored in the body, mostly in haemoglobin and ferritin.
• Free iron is toxic; hence, it's tightly controlled to avoid toxicity.
• Hepcidin is a key regulator in iron absorption and storage, affecting iron transfer from duodenal cells and macrophages.

Iron Transport

• Transferrin transports iron in the blood, with its capacity (TIBC) inversely correlating with iron stores.
• Transferrin saturation (TS) measures the percentage of transferrin bound to iron, normally around 33%.
• Serum transferrin receptor protein (TfR) aids in understanding erythropoiesis and differentiating iron deficiency anemia from other causes.

Student Questions & Answers

• Some questions about the characteristics of anemia and its etiologies, mechanisms and diagnosis using BM and FC.

Summary & Conclusion

• Concise overview of bone marrow examination, flow cytometry, anemia types, iron metabolism and its influence on anemia classification