Makindo Medical Notes

Related Subjects: |Sideroblastic Anaemia |Splenectomy |Paroxysmal Nocturnal Haemoglobinuria |Pernicious anaemia |Normocytic anaemiaa |Pyruvate Kinase deficiency |Blood Products - Platelets |Von Willebrand Disease

About Normocytic Anaemia

• Defined by a reduction in haemoglobin (Hb) levels for the patient's age and sex.
• Characterized by a normal red blood cell (RBC) size, indicated by a normal Mean Corpuscular Volume (MCV) range of 80-100 fL.
• Often presents without significant changes in RBC size or shape, but can indicate an underlying condition requiring further investigation.
• May present with symptoms of anaemia, including fatigue, pallor, shortness of breath, and, in more severe cases, tachycardia and chest pain.

Common Causes of Normocytic Anaemia

• Acute Bleeding: Can result from gastrointestinal tract bleeding (e.g., ulcers, diverticulosis), urinary tract bleeding, nosebleeds (epistaxis), uterine bleeding, retroperitoneal hemorrhage, or significant injuries (e.g., fractured pelvis or thigh). Patients may present with hypotension, tachycardia, and signs of shock. Haemoglobin levels may initially remain normal in acute cases but fall as fluid resuscitation dilutes the blood.
• Anaemia of Chronic Disease (ACD): Often associated with chronic inflammatory conditions (e.g., rheumatoid arthritis, inflammatory bowel disease), chronic infections (e.g., tuberculosis), and malignancies. In ACD, iron is sequestered in macrophages, reducing availability for erythropoiesis despite normal or elevated iron stores.
• Pregnancy: Physiological anaemia due to an increase in plasma volume relative to RBC mass, typically without underlying pathology. Important to monitor iron and folate levels, as deficiencies can complicate anaemia in pregnancy.
• Haemolysis: Involves the premature destruction of RBCs, which can be due to immune-mediated causes (e.g., autoimmune haemolytic anaemia), mechanical damage (e.g., from prosthetic heart valves), infections (e.g., malaria), or hereditary disorders (e.g., hereditary spherocytosis, sickle cell disease).
• Renal Disease: Chronic kidney disease (CKD) leads to decreased erythropoietin production, a hormone crucial for RBC production. Anaemia in CKD patients is often managed with erythropoiesis-stimulating agents.
• Malignancy: Anaemia may arise directly from bone marrow infiltration by cancer cells (e.g., leukaemia, lymphoma) or as a side effect of chemotherapy and radiation. Paraneoplastic syndromes associated with solid tumors may also cause anaemia.
• Bone Marrow Failure: Includes conditions such as aplastic anaemia (due to bone marrow suppression or autoimmune destruction of hematopoietic cells) and myelodysplastic syndromes (MDS), where ineffective haematopoiesis results in anaemia and potentially pancytopenia.

Investigations for Normocytic Anaemia

• Full Blood Count (FBC): Evaluates Hb, MCV, white cell count (WCC), and platelets to determine anaemia type and assess for pancytopenia or other cell line abnormalities.
• Urea and Electrolytes (U&E) and Liver Function Tests (LFTs): Useful for evaluating kidney and liver function, as dysfunction in either organ can contribute to anaemia.
• Iron Studies: Includes serum iron, ferritin, and Total Iron-Binding Capacity (TIBC) to assess iron stores and differentiate between iron-deficiency anaemia and anaemia of chronic disease.
• Vitamin Levels: Assess B12 and folate levels to rule out deficiencies that cause macrocytic anaemia, which can sometimes present with a normocytic MCV in early stages.
• Thyroid Function Tests (TFTs): Hypothyroidism can contribute to anaemia, so thyroid function should be evaluated if suspected.
• Reticulocyte Count: Elevated reticulocyte count may indicate haemolysis or recent blood loss, while a low count may suggest bone marrow suppression.
• Lactate Dehydrogenase (LDH): Elevated in haemolysis due to RBC destruction, along with increased bilirubin levels in some cases.
• Direct Antiglobulin Test (DAT): Also known as the Coombs test, used to detect autoimmune haemolytic anaemia by identifying antibodies or complement on RBCs.
• Bone Marrow Examination: Recommended if bone marrow failure, malignancy, or other hematologic abnormalities are suspected. A bone marrow biopsy can reveal evidence of marrow infiltration, aplasia, or myelodysplasia.

Other Considerations

• Peripheral Blood Smear: Morphologic examination of RBCs can reveal spherocytes, schistocytes, or abnormal cells that may indicate haemolysis, mechanical destruction, or bone marrow pathology.
• Inflammatory Markers: Elevated C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) may suggest chronic inflammatory or autoimmune disease as a cause of anaemia.
• Erythropoietin Levels: Especially useful in cases of suspected renal anaemia. Low erythropoietin levels may indicate renal origin, while elevated levels may suggest an ineffective erythropoiesis in myelodysplastic syndromes.
• Screening for Chronic Diseases: Chronic diseases, such as diabetes, rheumatoid arthritis, and other autoimmune conditions, are commonly associated with normocytic anaemia, and screening may reveal the underlying cause.