Erythrocytes/Anemias Flashcards
(38 cards)
Erythrocyte Function/structure
- About 4-6 million with 120 day lifespan
- Bi-concave form increases O2 access (main fund to transport O2)
- Mature RBC - no nucleus or mitochondria
- Hgb molecules fill RBC cytoplasm
Hgb Molecule
Made of alpha & beta chains
Contain 4 heme/globin groups
Each heme carries one O2 molecule via Fe binding site
Erythropoiesis
-Stimulated by Renal erythropoeitin in bone marrow
-After age 20, RBC produced in vertebrae, sternum, ribs, and pelvis marrow.
-Expand to more bones in case of anemia.
-Most rbc mature in marrow
-Nucleated RBC in blood indicate disease (infection)
>2% retic count means rapid formation of RBC=infection
-Old RBC lose reversible deformability and removed from circulation.
Reversible Deformability (RD)
- Cells must change shape as they pass capillaries/microcirculation.
- Ability to change back to biconcave shape
- Spleen is testing ground for RBC RD
Erythrocyte Destruction
- Hgb phagocytized by macrophages et broken down to heme, iron, and glob in.
- Heme - degraded to bilirubin. Unconj in blood, conj in liver.
- Iron - in blood as transferrin, TIBC, stored in liver or sk. muscle. Overload in liver/spleen called hemosiderin.
Body Responses to Anemia - true for all anemias
- Increased erythropoeitin & hematopoeitin
- Extramedullary hematopoeisis
- Blood shift to brain/heart
- Tachycardia (increased heart workload)
- Fatigue, weakness, dyspnea
- Tissue hypoxia
Morphological Classification of Anemia - know
- Normocytic, normochromic- decreased cell #
- Microcytic, hypochromic - abnormal hgb production, missing components
- Macrocytic, normochromic- large cells (juvenile,nucleated)
Definitions - know
Poikilocytosis - alteration in cell shape
Anisocytosis- “ “ size
Hemoglobinemia - hgb in plasma
Hemoglobinurea - urine exertion of hgb
Hemosideriuria - iron excretion via urine (brown)
Hemosiderosis - increased iron storage in kidneys, spleen, liver.
Normocytic Anemia - etiology
- Loss of RBCs - hemorrhage
- Increased destruction of RBCs (intra or extravascular hemolysis - premature lysis of erythrocytes in circulation) called hemolytic anemia
- Decreased production of RBCs (aplastic or chronic disease anemia)
Normocytic -Intravascular hemolysis
Intravascular hemolysis- breakdown in circulating blood (mechanical injury, transfusion reaction, exogenous factors)
Normocytic -Intravascular hemolysis- clinical manifestation
marked erythropoeisis hemoglobinemia hemoglobinuria hemisiderinuria hemisiderosis hyperbilirubinemia
Normocytic -Extravascular hemolysis
Defective rbcs trapped in spleen.
Anemias associated Hereditary spherecytosis, G6DP, sickle cell.
Normocytic - Extravas hemolysis -Hereditary Spherocytosis
- Etiology -autosomal genetic disorder
- Patho - gene mutation causing deficiency in Spectrin (alpha or beta) which is protein on cell surface.
- RBC membrane instability through tight spaces is compromised and becomes spherical. Unable to fit through spleen circulation therefore; destroyed.
Normocytic - Extravas hemolysis - Hereditary Spherocytosis- clinical manifestation
-Aplastic crisis
-Splenomegaly and jaundice
-Blood smear - anisocytosis, spherocytes, Howell-Jolly bodies
-Increased hematopoiesis
-Increased reticulocytes
Treatment - splenectomy
Normocytic - Extravas Hemolyisi - Glucose-6-Phosphate Dehydrogenase Deficiency G6DP
- Common in African Americans/Mediterranean/Males
- Etiology- mutation to G6DP gene
- Patho - G6DP deficiency - enzyme required for glutathione production (antioxidant)
- Lack of glutathione (deal with free radicals) results in oxidative stress damage to RBCs.
- -Older cells vulnerable, infections and drugs increase oxidative stress.
Normocytic, Extravas Hemolysis - G6DP clinical manifestation
- Hemolytic anemia - more severe in mediterraneon form
- Hemoglobinemia
- Hemoglobinuria
- Blood smear - spherical cells (poikilo and anisocytosis) and Heinz and bite cells.
Normocytic - Extravascular Hemolysis -Sickle Cell
- Epi - 1 in 500 Afr. Americans with 8% carrying the cell trait. Also occurs in Mid. Eastern and S. Asian countries.
- Etiology - mutation in beta globulin gene of hgb molecule
Normocytic - Ex. Hemolysis - Sickle cell path
- transforms hgbA (HbA) into hgb S.(HbS) Sickle cell disease = all hgbS (HbS)
- Decreased PaO2, pH, volume, dehydration and cold cause Hbs to sickle.
- Sickling - beta chaings in Hbs turn into viscous gel stretching into sickle shape.
- Initially reversible but eventually irreversible.
Normocytic - Ex. Hemolysis - sickle cell clinical manifestation
- Vaso-occlusive cirisis causing tissue hypoxia and pain (bones, liver, lung, brain, spleen, rhabdomyolysis).
- Sequestration crisis (RBCs pool in spleen, chronic hemolysis, decreased blood volume)
- Aplastic crisis - very few RBCs in circulation - erythrocyte survival rate to 10-20 days, infection prone)
- Blood smear - elevated retic count due to increase RBC production)
- Bone marrow hyperplasia and extramedulary hematopoiesis.
Normocytic - Extravas Hemolysis - Sickle cell treatment
- Hydroyxurea forces RBCx to make fetal hgbjj which does not sickle
- NO decreases platelet aggregation
- Symptom support (O2, IV fluids, pain mgmt)
Normocytic anemias -Decreased RBC Production -
Aplastic Anemia
Failure or suppression of myeloid stem cells (pancytopenia)
Etiology - idiopathic (immune mediated suppression), acquired (drugs/chemicals/radiation)
Normocytic anemias -Decreased RBC Production - Aplastic Anemia clinical manifestation
pancytopenia (anemia, neutropenia, thrombocytopenia)
No splenic enlargement
Bone marrow hypo cellular
Treatment - immunosuppressants if idiopathic. If acquired, remove offending source.
Normocytic Anemias - Decreased RBC Production - Anemia of Chronic Disease
-Epi - common in hospitalized pts.
-Patho - production of TNFa, IL-1, IL-6, IL10
Inflammation alters normal iron metabolism, decreased iron for erythropoiesis leads to decreased RBC production.
Normocytic Anemias - Decreased RBC Production - Anemia of Chronic Disease - clinical manifestation
- mild anemia
- low serum iron
- reduced tibc
- high serum ferritin
- low erythropoietin levels