Caused by malignant proliferation of plasma cells producing monoclonal immunoglobulin (M protein) that usually affects older adults (~60-70 years). This causes bone marrow infiltration and osteolytic bone lesions. Clinical Features (CRAB) * C: HyperCalcemia → confusion, constipation, polyuria * R: Renal failure (due to light chain cast nephropathy) * A: Anemia (normocytic, normochromic) * B:

Understanding RBC Morphology Normocytic and normochromic refer to normal erythrocytes (RBCs). The suffix "-cytic" refers to cell size, while "-chromic" indicates color intensity. Size Classification (Cytic) * Macrocytic: Large cells, typically associated with folate/B12 deficiency * Microcytic: Small cells, typically associated with iron deficiency Color Classification (Chromic)

B-Cell Selective IgA Deficiency * Most common primary immunodeficiency * Defect: B-cells fail to produce IgA * Presentation: * Asymptomatic (often) * Recurrent mucosal infections: sinopulmonary, GI (Giardia) * Anaphylaxis to blood products (anti-IgA antibodies) * ↑ risk of celiac disease, autoimmune disorders * Labs: ↓ IgA only, normal IgG/IgM * Treatment: Supportive; avoid IVIG (contains IgA, can trigger anaphylaxis)

Thalassemia is a hereditary blood disorder characterized by decreased synthesis of globin chains, the protein components that make up hemoglobin. Normal Hemoglobin Structure Normal adult hemoglobin (HbA) consists of two alpha and two beta globin chains. The genes responsible for producing these chains include: * Four alpha globin alleles (two copies