Heme Flashcards
Variations in normal hemoglobin
Fetal hgb and polycythemia
Hemolytic disease of the new born
Aging (men decrease in testosterone) is not physiologic
Altitude greater than 1000 meters above sea level
Smoking increases carboxyhemoglobin increase in hgb to compensate
Removal and byproducts of RBCs
Life span about 120 days
Removed by macrophages (spleen)
Cells decrease ATP-cell membrane becomes more frail and digested by preolytic and lipolytic enzymes in phagolysosomes
Heme and globulin dissociate-iron is recycle as ferritin and globulin becomes amino acid
Metabolism of bilirubin
Porphyria reduces to unconjugated bilirubin
Conjugated (water and soluble) excreted by liver, intestine or bile
Bacteria in intestinal linen=conjugated bilirubin to urobilinogen
Excreted in feces
Some is reabsorbed and excreted by the kidneys
Gallstone if chronically elevated bili excretion
Oxygen dissociation curve
Right
High pCO2, low affinity for 02, high hydrogen, low pH, high 2-3 DPG, high temp
Left
Low pCO2, low hydrogen, low 2,3 DPG, low temp
HbA
Alpha 2 beta 2 92% of adult hgb
HbA1c
Alpha 2 (beta Nh glucose) 5% of adult hgb, high in DM
HbA2
Alpha 2 beta 2-2% of adult hgb high in beta thalassemia
HbF
Alpha 2 Y 2 major fetal hgb from 3rd to 9th month of gestation, promotes o2 transfer across platelets, high in beta thalassemia
Hb grower 1,2 and Hb Portland
Present in early embryo, function unknown
Trigger of RBC production
Low o2 due to anemia/hypoxia
Decreased blood volume
Poor blood flow
Pulmonary disease
Increased levels of androgens
Key components of a hemoglobin molecule
Krebs cycle form succinylco-A
Each molecule has 2 polypeptide chain globulins alpha and beta
4 components of the iron plus protoporphyrin (heme)
Heme synthesized in the mitochondria can carry one molecule of 02 each
Protoporphyrin bound with ferrous iron (binding oxidizes to Fe2+ to oxyhemoglobin) releases 02 deoxyhemoglobin without the reaction Fe 3+ Hb (methoemoglobin) cannot bind to 02
4 components of sets of alpha and beta each can carry one 02 molecule (max 4 molecule per RBC)
Hematopoiesis
7 days
Controlled by erythropoietin in the kidneys tissue 02 levels stimulate bone marrow
Flat bones of pelvis, vertebrae, cranium and mandible
Transcription of erythropoietin is mediated by hypoxia induced factor 1
Epo binds to receptors and stimulates erythroid cell division and proliferation and inhibits apoptosis
In infants process starts in the yolk sac then switches to liver at two months after birth goes to marrow
If extra RBC are needed process occurs in liver and spleen
Pluripotent
Pluripotential hematopoietic stems cells in the bone marrow differentiate
Committed stem cells turn into colony forming units then blastocysts and immature RBC erythroblasts, reticulocytes and then erythrocytes
Anemia
Reduction in total erythrocytes, hgb, hct
Women hgb less than 12
Men hgb less than 13
MCV
Mean corpuscular volume aka size
MCHC
Mean corpuscular hemoglobin concentration aka amount of hgb in RBC compared to size and color
RDW
Red cell distribution width
Microcytic anemia
MCV less than 80
If serum iron and ferritin low-iron deficiency anemia
If serum urine normal or elevated, serum ferritin normal or elevated, or TIBC normal, hgb electrophoresis normal is alpha abnormal in beta- thalassemias
Serum iron normal or deceased, serum ferritin normal or elevated, TIBC normal or decreased, hgb electrophoresis is normal-chronic disease
Normocytic Anemia
MCV 80-100
Causes acute blood loss, chronic disease, hemolysis, infection, inflammation, malignancy, renal insufficiency, sickle cell
Marcocytic anemia
MCV greater than 100
If serum B12 low, hemocysteine elevated, serum folate low
Then test methylmaloic acid
If elevated- vitamin B12 deficiency
If normal- folate deficiency
If serum B 12 and folate are normal causes include alcoholism, bone marrow disease, hypothyroidism, liver disease, medication like chemotherapy and antivirals
Iron studies
Iron 70% in hgb/30% stored
Ferritin-acute phase reactant/amount stored of iron
Transferrin-ability of body to transport
Iron brining capacity (TIBC) protein available to bind iron (high in iron deficiency anemia, low in inflammatory or malignancy)
Types of anemia
Anemia of chronic illness, hemolytic, aplastic, sickle cell, pernicious, folate deficiency
Anemia of chronic illness
Rule out diagnosis
2nd most common
Due to chronic infection, inflammation, chronic disease
Pro inflammatory cytokines, inhibit erythropoietin production. Destroys immature erythroblasts
Stimulates release of hepicidin- control irons absorption in blood and GI tract, blocks release of iron reticuloendothelial system, decreases oral iron absorption leading to deficiency
Hemolytic anemia
Destruction of RBCs due to genetics, ABO incompatibility, autoimmune (lupus, RA), drugs (NSAID, cephalosporins) newborns- hyperbilirubinemia,
High bili, high pH, high uric acid, high hemoglubinuria, decreased haptoglobin
Aplastic anemia
Usually stem cell disorder
Congenital, chemo, viral, autoimmune
Bone marrow bx
All cells lines down
Iron deficiency anemia
Chronic blood loss, diet, malabsorption, pregnancy, increase in children during growth periods
Sickle cell
Autosomal recessive-hemolytic
Disease or trait
1:500 AA
hgb low 02 capacity
Exacerbations/crisis-infection, dehydration, hypoxia, vasoocclusion, pain
Increased risk for MI, CVA, pulm injury.
Pernicious anemia
Low B12
Less effective DNA synthesis and short RBC life
Unable to absorb B12 (lack intrinsic factor), dietary, autoimmune
Parasthesias, balance, oral pain, increase in homocysteine
Folate deficiency anemia
Impaired RNA/DNA synthesis
Dietary deficiency, poor absorption, drugs (ASA) maternal deficiency can results in neural tube defects