1. Hematopoiesis in embryonic stage: 1. Mesodermal hematopoiesis stage: starts at 3w, starts to decrease at 6th week, originates from yolk sac 2. Liver and spleen hematopoiesis stage: starts at 6-8w, peaks at 4-5w, and decreases after 6 months , derived from liver and spleen 3. Bone marrow hematopoiesis period: begins in the 4th month, becomes the only hematopoietic organ 2-5w after birth, derived from bone marrow 2. Postnatal hematopoiesis: 1. Bone marrow hematopoiesis: all bone marrow in infants and young children is red Bone marrow is all involved in hematopoiesis. Yellow bone marrow (adipose tissue) begins to replace 5-7 years old. In adults, red bone marrow is limited to the ribs, sternum, spine, pelvis, skull, clavicle, and scapula. But yellow bone marrow can be converted into red bone marrow. 2. Hematopoiesis outside the bone marrow: anemia in infants and young children---compensatory hyperplasia of liver and spleen---swelling---nucleated red blood cells/immature neutrophils in peripheral blood---bone marrow. External hematopoiesis

1. Number of red blood cells and hemoglobin amount: 1. RBC: 5.0~7.0×10 to the 12th power 2. Hb: 150~220/L 3. 2-3 months after birth, RBC begins to decrease---Physiological anemia 4 , RBC&Hb reaches adult level at 12 years old 2. White blood cell count and classification: 1. At birth: 15~20×10 to the 9th power 2. At 1w: 12×10 to the 9th power 3. Infancy: 10×10 to the 9th power Power 4. Reach adult level after 8 years old. 3. PLT: 100~300×10 to the 9th power. 4. Hb type: 1. At birth: (1) HbF: 70% (2) HbA: 30% (3) HbA2: <1% 2. In adults: (1) HbF: <2% (2) HbA: 95% (3) HbA2: 2-3%

Definition: It is an anemia caused by reduced hemoglobin synthesis due to iron deficiency in the body. Clinically, it is characterized by microcytic hypochromic anemia, reduced serum ferritin and ineffective iron treatment.

Causes: 1. Innate insufficient iron storage 2. Insufficient iron intake 3. Growth and development factors 4. Iron absorption disorder 5. Excessive iron loss

Iron metabolism: 1. Iron content and distribution in the human body: (1) Male: 50mg/kg (2) Female: 35mg/kg (3) Newborn: 75mg/kg 2. Source of iron: (1) External source Sexual iron: food (2) Endogenous iron: Hb iron released by aging/destruction of red blood cells in the body 3. Iron absorption and transport: (1) Mainly absorbed as Fe2 in the duodenum & upper jejunum (2) Enters the intestine Mucosal Fe2 is oxidized to Fe3 (3) Part of it is combined with intracellular apoferritin to form ferritin (4) The other part is combined with carrier protein and enters the blood, where it combines with transferrin in plasma 4. Utilization and storage of iron: It is not present in the body. The utilized iron is stored in the form of ferritin & hemosiderin 5. Iron excretion: (1) Intestine: detached intestinal mucosal cells, WBC, bile (2) Kidney 6. Iron requirements: (1) Adults : 1mg/d (2) 4 months to 3 years old: 1mg/kg/d (3) Premature infants: 2mg/kg/d

Pathogenesis: 1. Impact on the blood system: (1) Iron deficiency phase (2) Iron deficiency phase of erythropoiesis (3) Iron deficiency anemia phase 2. Impact on other systems: (1) Affects the synthesis of myoglobin (2) Reduce the activity of various iron-containing enzymes (3) Cause tissue and organ abnormalities (4) Cause a decrease in cellular immune function, making you susceptible to infectious diseases

Clinical manifestations: 1. General manifestations: pale skin and mucous membranes (commonly seen on lips, oral mucosa, and nail beds), prone to fatigue, and inactive. 2. Extramedullary hematopoietic manifestations: mild enlargement of the liver and spleen [hematopoiesis of the liver and spleen in children] Compensation, adults will not] 3. Non-hematopoietic system symptoms: a few have pica

Laboratory tests: 1. Peripheral blood picture: microcytic hypochromic anemia, expanded mean corpuscular volume (MCV) in the central light-stained area <80fl, mean corpuscular hemoglobin (MCH) <26pg, and mean corpuscular hemoglobin concentration (MCHC) <310g/ L 2. Bone marrow: old nuclei and young plasma, mainly medium and late red blood cells hyperplasia 3. Examination related to iron metabolism: (1) Serum ferritin SF: decreased (2) Red blood cell free protoporphyrin: increased, when >0.9μmol/L indicates intracellular iron deficiency (3) Serum iron SI and transferrin saturation TS: decreased (4) Total iron binding capacity TIBC: increased [transferrin saturation decreased---a lot of empty- --Increased ability to bind] 4. Bone marrow can be stained with iron: bone marrow smears are stained with Prussian blue for microscopic examination

Treatment: 1. General treatment: strengthen nursing, avoid infection, increase iron-rich foods 2. Remove the cause of the disease 3. Iron treatment [The first thing to increase is intracellular iron enzyme (reticulocytes in adults)-- - Increased reticulocytes - increased HB - increased RBC - take another 6-8w (adults 4-6 months) to replenish stored iron]: (1) Oral iron (2) Injectable iron Agent 4. Red blood cell transfusion